How to study the physiology of digestion in the human body

In this Article

In this Article

In this Article

Physiology is the study of how the human body works. It describes the chemistry and physics behind basic body functions, from how molecules behave in cells to how systems of organs work together. It helps us understand what happens in a healthy body in everyday life and what goes wrong when someone gets sick.

Most of physiology depends on basic research studies carried out in a laboratory. Some physiologists study single proteins or cells, while others might do research on how cells interact to form tissues, organs, and systems within the body.

Physiology vs. Anatomy

While human anatomy is the study of the body’s structures, physiology is the study of how those structures work. An imaging scan like an X-ray or ultrasound can show your anatomy, but doctors use other tests — like urine and blood tests or electrocardiograms (EKGs) — to reveal details about your body’s physiology.

What Physiology Tells Us About the Body

Doctors use physiology to learn more about many different organ systems, including:

• The cardiovascular system — your heart and blood vessels
• The digestive system — the stomach, intestines, and other organs that digest food
• The endocrine system — glands that make hormones, the chemicals that control many body functions
• The immune system — your body’s defense against germs and disease
• The muscular system — the muscles you use to move your body
• The nervous system — your brain, spinal cord, and nerves
• The renal system — your kidneys and other organs that control the fluid in your body
• The reproductive system — sex organs for men and women
• The respiratory system — your lungs and airways
• The skeletal system — bones, joints, cartilage, and connective tissue

For each system, physiology sheds light on the chemistry and physics of the structures involved. For example, physiologists have studied the electrical activity of cells in the heart that control its beat. They’re also exploring the process by which eyes detect light, from how the cells in the retina process light particles called photons to how the eyes send signals about images to the brain.

Physiology revolves around understanding how the human body maintains a steady state while adapting to outside conditions, a process called homeostasis. How do your organ systems keep your temperature relatively stable in different environments? How does your body keep your blood sugar and other chemical levels constant even when you eat different foods? These are the kinds of questions that physiologists aim to answer.

Continued

Physiology in Medicine

By shedding light on normal body functions, physiology can teach lessons about what goes wrong in disease. For instance, physiologists have figured out how different types of cells in the pancreas release hormones to control blood sugar levels. That helps doctors understand and treat diabetes.

The field also offers insights into how to make the human body work more efficiently. It’s often part of sports medicine, where knowing how the body adapts to physical challenges helps elite athletes improve their performance, avoid injury, and recover faster.

The History of Physiology

Anatomy is visible, and ancient doctors and scientists studied it through dissections, surgeries, and observation. But how the body actually works is harder to explore. This means that physiology is a more modern science.

Early explanations of how organs or functions of the human body might work were often guesses, based on processes that were familiar to scientists. For example, some thought the formation of an embryo was similar to how milk turns into cheese. Other early scientists compared blood flow throughout the body to weather patterns.

In the 17th century, microscopes helped shed new light on the cells that make up the human body, leading to a new understanding of physiology. More recently, tools like gene sequencing technologies and new types of body scans have given physiologists an expanded vision of the human body.

Sources

American Physiological Society: “What is Physiology?”

Oregon State Open Textbooks: “Anatomy and Physiology Chapter 1.1: How Structure Determines Function.”

The Physiological Society: “What is Physiology?”

University of Cambridge: “What is Physiology?”

Advances in Physiology Education: “The “core principles” of physiology: what should students understand?”

Advances in Physiology Education: “Clinical physiology: a successful academic and clinical discipline is threatened in Sweden.”

Horstmanshoff, M., et al. Blood, Sweat and Tears: The Changing Concepts of Physiology from Antiquity to Early Modern Europe, BRILL, 2012.

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Matthew has a Master of Arts degree in Physics Education. He has taught high school chemistry and physics for 14 years.

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What is the Human Digestive System?

We all love food. It’s tasty, and fun, and absolutely vital for life. But have you ever wondered how your body turns all that yummy food into the stuff the body needs to work? The body needs energy, and it needs it in the form of glucose (sugar). So how do we get from complex food that contains lots of things that aren’t sugar, to pure, sugary energy?

The system in your body that does this important job is called the digestive system. The digestive system is a set of organs, passageways, and glands that work together to process complex food into the simple molecules your body needs. The digestive system includes your teeth, mouth, esophagus, stomach, small intestine, large intestine and rectum. Let’s go through each step in the digestive process one at a time.

The human digestive system

The Teeth and Mouth

The first step in the process of digestion is the teeth and mouth. You put food in your mouth, and the first thing that happens is that it gets chewed and broken down into smaller parts. This is important, because it not only makes it easier to swallow, but it also increases the surface area of the food, making other parts of digestion function better.

Teeth break food into smaller pieces.

One of those other parts is the mixing of food with saliva. Saliva contains enzymes which break down the cell walls of the food, and start breaking complex carbohydrates into simpler carbohydrates and sugars. When the food is sufficiently digested, we swallow it, and it goes through a tube called the esophagus until it reaches the stomach. A muscle just outside the stomach forces it inside, and will even work if you’re upside down.

The Stomach

A lot of action happens in the stomach. Your stomach contains strong acids that break down the food further. It churns the food in the acid to form a mixture called chyme. Enzymes are also released by the stomach, which are particularly good at breaking down proteins in the food you ate. Food will often stay in the stomach for hours, until it reaches a creamy or liquidy consistency, before being gradually squirted into the next section – the small intestine. It can take anywhere from two to six hours for this to happen.

The process by which enzymes break molecules into smaller ones

The Small and Large Intestines

The next part of the digestive system is the small intestine, which is a long, windy and thin tube that snakes its way around the lower part of your belly. Here the food is mixed with bile and other enzymes, which are created by the liver and pancreas, to break down the molecules in the food even further. Once the food has been turned into glucose, those molecules are absorbed by the wall of the small intestine and move into the blood, where they provide energy for the body. The small intestine also absorbs vitamins, minerals, simple fatty acids and amino acids. This is another slow, gradual process and takes 3-6 hours.

After the small intestine, the food continues to the large intestine, which arches over the top of the small intestine before heading down towards the rectum. The large intestine’s first job is to absorb all the water and electrolytes (like salt) in the digested food. This is also where the remaining waste products dry out to form feces that will later be expelled through the anus. But this takes a long time – food can take 24-36 hours to travel through the large intestine.

And that’s it: the long journey of every meal you eat, from your mouth until you flush it down the toilet. It might not seem all that exciting, but it’s an amazingly complex process that you literally couldn’t live without.

Other Parts: The Liver, Pancreas and Gallbladder

The liver, pancreas, and gallbladder are all parts of the digestive system that we haven’t talked about yet. They have several jobs. Many of the digestive juices we talked about are produced by these organs. The liver produces bile, which is stored in the gall bladder until needed, and the pancreas creates all those enzymes we discussed. The pancreas also creates hormones, though this isn’t part of digestion.

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Structural Organisation in Animals Table of.

Photosynthesis in Higher Plants Table of Content.

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Cell: Structure and Functions Table of Content.

Principles of Inheritance and Variation Table of.

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Introduction To Diversity In The Living World.

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Biodiversity The sum total of all the variety of.

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Digestion is accomplished by mechanical and chemical processes .

• The buccal cavity performs two major functions, mastication of food and helping in swallowing.
• The teeth and the tongue with the help of saliva masticate and mix up the food thoroughly.
• Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus.The bolus is then conveyed into the pharynx and then into the oesophagus by swallowing and down through the oesophagus by successive waves of muscular contractions called peristalsis.
• The saliva secreted into the oral cavity contains electrolytes and enzymes, salivary amylase and lysozyme .

Starch + Ptyalin (enzyme) -> >> Maltose

• The chemical process of digestion is initiated in the oral cavity by enzyme, the salivary amylase. About 30 per cent of starch is hydrolysed here by this enzyme (optimum pH 6.8) into a disaccharide – maltose. Lysozyme present in saliva acts as an antibacterial agent that prevents infections.

The mucosa of stomach has gastric glands. Gastric glands have three major types of cells namely –
(i) mucus neck cells which secrete mucus ;
(ii) peptic or chief cells which secrete the proenzyme pepsinogen ; and
(iii) parietal or oxyntic cells which secrete HCl and intrinsic factor
(factor essential for absorption of vitamin B12).
– The stomach stores the food for 4-5 hours. The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and is called the chyme .

• The proenzyme pepsinogen, on exposure to hydrochloric acid gets converted into the active enzyme pepsin, the proteolytic enzyme of the stomach.
• Pepsin converts proteins into proteoses and peptones (peptides).

Proteins + Pepsin(enzyme) ->>>>> Proteases and Peptones

• The mucus and bicarbonates present in the gastric juice play an important role in lubrication and protection of the mucosal epithelium from excoriation by the highly
  concentrated hydrochloric acid. HCl provides the acidic pH (pH 1.8)
  optimal for pepsins.
• Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteins.

Casein (milk protein) + Renin(enzyme) ->>>>> Paracaesin

Paracaesin + Calcium ->>>>> Calcium paracaseinate

Calcium paracaseinate + pepsin (enzyme) ->>>> Peptones

• Small amounts of lipases are also secreted by gastric glands which helps in digesting fats into fatty acids.

Fat + Lipase (enzyme) ->>>>> Fatty acid + Glycerol

• The bile, pancreatic juice and the intestinal juice are the secretions released into the small intestine.
• Pancreatic juice and bile are released through the hepato-pancreatic duct.
• The pancreatic juice contains inactive enzymes – trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases and nucleases.

Protein + Trypsin (enzyme) ->>>>> Proteases and peptones

Protein + Chymotrypsin (enzyme) ->>>> Proteases and peptones

Peptides + Carboxypeptidases (enzyme) ->>>> Dipeptides + Aminoacids

Fats + Lipase (enzyme) ->>>> Fatty acid + Glycerol

DNA/RNA (nucleic acids ) + DNAse/RNAse ( nucleases/enzymes ) ->>>> Nucleotides

• The bile released into the duodenum contains bile pigments (bilirubin and bili-verdin), bile salts, cholesterol and phospholipids but no enzymes. Bile helps in emulsification of fats, i.e., breaking down of the fats into very small micelles. Bile also activates lipases.
• The intestinal mucosal epithelium has goblet cells which secrete mucus.
  The secretions of the brush border cells of the mucosa alongwith the secretions of the goblet cells constitute the intestinal juice.
• This juice contains a variety of enzymes like disaccharidases (e.g., maltase), dipeptidases, lipases, nucleosidases, etc. The mucus alongwith the bicarbonates from the pancreas protects the intestinal mucosa from acid as well as provide an alkaline medium (pH 8) for enzymatic activities.
• The breakdown of biomacromolecules mentioned above occurs in the duodenum region of the small intestine. The simple substances thus formed are absorbed in the jejunum and ileum regions of the small intestine.

• The undigested and unabsorbed substances are passed on to the large intestine.

No significant digestive activity occurs in the large intestine. The functions of large intestine are:
(i) absorption of some water, minerals and certain drugs;
(ii) secretion of mucus which helps in adhering the waste (undigested) particles together and lubricating it for an easy passage.

• The undigested, unabsorbed substances called faeces enters into the caecum of the large intestine through ileo-caecal valve, which prevents the back flow of the faecal matter. It is temporarily stored in the rectum till defecation.

The branches of science that will help you understand the body parts and functions are anatomy and physiology. Anatomy deals with the study of the human body (the components, structure and position) and physiology the study of how the body functions.

Body Systems

The body comprises several systems including the: Cardiovascular system, Digestive system, Endocrine system, Muscular system, Neurological system, Respiratory system and the Skeletal system.

The Digestive System

The functions of the digestive system are:

• Ingestion – eating food
• Digestion – the breakdown of the food
• Absorption – extraction of nutrients from the food
• Defecation – removal of waste products

The digestive system also builds and replaces cells and tissues that are continually dying.

Digestive Organs

The digestive system is a group of organs (Buccal cavity (mouth), pharynx, oesophagus, stomach, liver, gallbladder, jejunum, ileum and colon) that break down the chemical components of food, with digestive juices, into tiny nutrients which can be absorbed to generate energy for the body.

The Buccal Cavity

Food enters the mouth and is chewed by the teeth, turned over and mixed with saliva by the tongue. The sensations of smell and taste from the food set up reflexes which stimulate the salivary glands.

The Salivary glands

These glands increase their output of secretions through three pairs of ducts into the oral cavity and begin the process of digestion.

Saliva lubricates the food enabling it to be swallowed and contains the enzyme ptyalin which serves to begin to break down starch.

The Pharynx

Situated at the back of the nose and oral cavity receives the softened food mass or bolus by the tongue pushing it against the palate, which initiates the swallowing action.

At the same time, a small flap called the epiglottis moves over the trachea to prevent any food particles getting into the windpipe.

From the pharynx onwards, the alimentary canal is a simple tube starting with the salivary glands.

The Oesophagus

The oesophagus travels through the neck and thorax, behind the trachea and in front of the aorta. The food is moved by rhythmical muscular contractions known as peristalsis (wave-like motions) caused by contractions in longitudinal and circular bands of muscle. Antiperistalsis, where the contractions travel upwards, is the reflex action of vomiting and is usually aided by the contraction of the abdominal muscles and diaphragm.

The Stomach

The stomach lies below the diaphragm and to the left of the liver. It is the widest part of the alimentary canal and acts as a reservoir for the food where it may remain for between 2 and 6 hours. Here the food is churned over and mixed with various hormones, enzymes including pepsinogen which begins the digestion of protein, hydrochloric acid, and other chemicals; all of which are also secreted further down the digestive tract.

The stomach has an average capacity of 1 litre, varies in shape, and is capable of considerable distension. When expanding, this sends stimuli to the hypothalamus, which is the part of the brain and nervous system controlling hunger and the desire to eat.

The wall of the stomach is impermeable to most substances, although it does absorb some water, electrolytes, certain drugs, and alcohol. At regular intervals a circular muscle at the lower end of the stomach, the pylorus opens allowing small amounts of food, now known as chyme to enter the small intestine.

Small Intestine

The small intestine measures about 7m in an average adult and consists of the duodenum, jejunum, and ileum. Both the bile and pancreatic ducts open into the duodenum together. The small intestine, because of its structure, provides a vast lining through which further absorption takes place. There are a large lymph and blood supply to this area, ready to transport nutrients to the rest of the body. Digestion in the small intestine relies on its secretions plus those from the pancreas, liver, and gallbladder.

The Pancreas

The Pancreas is connected to the duodenum via two ducts and has two main functions:

1. To produce enzymes to aid the process of digestion
2. To release insulin directly into the bloodstream to control blood sugar levels

Enzymes suspended in the very alkaline pancreatic juices include amylase for breaking down starch into sugar and lipase which, when activated by bile salts, helps to break down fat. The hormone insulin is produced by specialised cells, the islets of Langerhans, and plays an important role in controlling the level of sugar in the blood and how much is allowed to pass to the cells.

The Liver

The liver, which acts as a large reservoir and filter for blood, occupies the upper right portion of the abdomen and has several vital functions:

1. Secretion of bile to the gallbladder
2. Carbohydrate, protein and fat metabolism
3. The storage of glycogen ready for conversion into glucose when energy is required.
4. Storage of vitamins
5. Phagocytosis – ingestion of worn-out red and white blood cells, and some bacteria

The Gallbladder

The gallbladder stores and concentrates bile which emulsifies fats, making them easier to break down by the pancreatic juices.

The Large Intestine

The large intestine averages about 1.5m long and comprises the caecum, appendix, colon, and rectum. After food is passed into the caecum a reflex action in response to the pressure causes the contraction of the ileocolic valve, preventing any food returning to the ileum. Here most of the water is absorbed, much of which was not ingested, but secreted by digestive glands further up the gastrointestinal tract. The colon is divided into the ascending, transverse and descending colons, before reaching the anal canal where the indigestible foods are expelled from the body.

Effect of exercise on the digestive system

Most exercise has a positive effect on the digestive system helping to quell appetite and increase metabolism. Some endurance events sometimes cause competitors to have an upset stomach and diarrhoea.

Related References

The following references provide additional information on this topic:

• LIPSKI, E. (2012) Digestive Wellness: Strengthen the Immune System and Prevent Disease Through Healthy Digestion. McGraw-Hill
• Health Gut, Health You – The personalized plan to transform your health from the inside out.

Page Reference

If you quote information from this page in your work, then the reference for this page is:

• MACKENZIE, B. (2001) Physiology – Digestive System [WWW] Available from: [Accessed

Related Pages

The following Sports Coach pages provide additional information on this topic:

A simple overview of how different molecules are absorbed into the blood stream in the small intestine.

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• Examinator AQA
• Subject Biology
• Unit Unit 2 BIOL2 – The variety of living organisms

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Author(s): Andrew Allott, David Mindorff

• Edition: februari 2014
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Affiliation

• 1 Microbiology and Gut Biology Group, Ninewells Hospital Medical School, University of Dundee, UK.

• PMID: 21992950
• DOI: 10.1097/MCG.0b013e31822fecfe

Authors

Affiliation

• 1 Microbiology and Gut Biology Group, Ninewells Hospital Medical School, University of Dundee, UK.

• PMID: 21992950
• DOI: 10.1097/MCG.0b013e31822fecfe

Abstract

The human large intestine harbors a complex microbiota containing many hundreds of different bacterial species. Although structure/function relationships between different components of the microbiota are unclear, this complex multicellular entity plays an important role in maintaining homeostasis in the body. Many of the physiologic properties of the microbiota can be attributed to fermentation and the production of short-chain fatty acids (SCFAs), particularly acetate, propionate, and butyrate. In healthy people, fermentation processes are largely controlled by the amounts and different types of substrate, particularly complex carbohydrates that are accessible to bacteria in the colonic ecosystem. However, other factors impact on bacterial metabolism in the large gut, including large bowel transit time, the availability of inorganic terminal electron acceptors, such as nitrate and sulfate, and gut pH. They all affect the types and levels of SCFA that can be formed by the microbiota. This is important because to a large extent, acetate, propionate, and butyrate have varying physiologic effects in different body tissues. Prebiotics such as galactooligosaccharides together with inulins and their fructooligosaccharide derivatives have been shown to modify the species composition of the colonic microbiota, and in various degrees, to manifest several health-promoting properties related to enhanced mineral absorption, laxation, potential anticancer properties, lipid metabolism, and anti-inflammatory and other immune effects, including atopic disease. Many of these phenomena can be linked to their digestion and SCFA production by bacteria in the large gut.

Correction(s) for this article

Corrigendum

• Volume 76 Issue 5 Journal of Food Science
• pages: viii-viii
• First Published online: June 1, 2011

Authors Kong and Singh are with Dept. of Biological and Agricultural Engineering, Univ. of California, Davis, CA 95616. Author Singh is also with Riddet Inst., Massey Univ., Palmerston North, New Zealand. Direct inquiries to author Singh (E‐mail: [email protected]).

Authors Kong and Singh are with Dept. of Biological and Agricultural Engineering, Univ. of California, Davis, CA 95616. Author Singh is also with Riddet Inst., Massey Univ., Palmerston North, New Zealand. Direct inquiries to author Singh (E‐mail: [email protected]).

Authors Kong and Singh are with Dept. of Biological and Agricultural Engineering, Univ. of California, Davis, CA 95616. Author Singh is also with Riddet Inst., Massey Univ., Palmerston North, New Zealand. Direct inquiries to author Singh (E‐mail: [email protected]).

Authors Kong and Singh are with Dept. of Biological and Agricultural Engineering, Univ. of California, Davis, CA 95616. Author Singh is also with Riddet Inst., Massey Univ., Palmerston North, New Zealand. Direct inquiries to author Singh (E‐mail: [email protected]).

Abstract

Abstract: The objective of this study was to develop an in vitro stomach model, the Human Gastric Simulator (HGS), for studying gastric digestion of foods. The HGS is designed in such a way as to simulate the continuous peristaltic movement of stomach walls, with similar amplitude and frequency of contraction forces as reported in vivo . The HGS mainly consists of a latex vessel, simulating the stomach chamber, and a series of rollers secured on belts that are driven by motor and pulleys to create a continuous contraction of the latex wall. It also incorporates gastric secretion, emptying systems, and temperature control that enable accurate simulation of dynamic digestion process for detailed investigation of the changes in the physical chemical properties of ingested foods. The simulated gastric contraction force demonstrates a similar pattern as in vivo stomach forces. The precise control of gastric secretion and emptying and the adjustable mechanical forces in the HGS provide a useful tool to study transformation of food constituents under simulated physiological conditions.

Practical Application: HGS could be used to study changes in the physical and chemical properties of gastric contents, and transformation of food constituents that occur during simulated digestion, and the influence of physiological conditions including acid and enzyme secretion and contraction forces on disintegration kinetics of foods and nutrient release.

Enhancing oral processing by prolonged chewing influences appetite and food intake.

Meta-analysis revealed that chewing significantly reduced self-reported hunger.

Systematic review revealed an effect of chewing on food intake.

Increasing the number of chews per bite increased gut hormone release.

Mastication promotes satiety by influencing appetite, intake and hormone release.

Abstract

To conduct a systematic review of the effects of chewing on appetite, food intake and gut hormones, and a meta-analysis of the effects of chewing on self-reported hunger.

Objectives

To seek insights into the relationship between chewing, appetite, food intake and gut hormones, and to consider potentially useful recommendations to promote benefits of chewing for weight management.

Materials and methods

Papers were obtained from two electronic databases (Medline and Cochrane), from searches of reference lists, and from raw data collected from the figures in the articles. A total of 15 papers were identified that detailed 17 trials. All 15 papers were included in the systematic review; however, a further five studies were excluded from the meta-analysis because appropriate information on hunger ratings was not available. The meta-analysis was conducted on a total of 10 papers that detailed 13 trials.

Results

Five of 16 experiments found a significant effect of chewing on satiation or satiety using self-report measures (visual analogue scales, VASs). Ten of 16 experiments found that chewing reduced food intake. Three of five studies showed that increasing the number of chews per bite increased relevant gut hormones and two linked this to subjective satiety. The meta-analysis found evidence of both publication bias and between study heterogeneity (IA 2 = 93.4%, tau 2 = 6.52, p

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Which Major Is Better for Med School: Biology or Biochemistry?

Throughout your time as a student, it’s inevitable that you will have to study several of the basic sciences. The basic study of the biological sciences usually starts as early as high school with an introduction to basic biology. Often, general biology begins with a general study of life and includes the dissection of various specimens such as a frog, fetal pig or heart.

However, if you choose to study the medical sciences in college, your study of biology will become much more complex. For example, majors including pre-med, nursing or microbiology will require additional study in anatomy and physiology or biology.

What’s the Study of Biology?

The study of general biology is usually included in most science curriculum plans. The study of biology is the study of life. Often this study begins at the cellular level including cell structure, transport and cell division. From there, the study shifts to genetics and on to reproduction.

The study of life will usually start with the study of plants and then expand into animal reproduction. Lastly, the study of biology will cover the major systems in the human body including circulation, respiration and digestion.

To better understand how these systems work, often time students will be required to practice dissections of certain specimens. These may include a cow or sheep heart, owl pellets or fetal pig. There may be some work with microscopes to better understand cellular life.

What’s the Study of Anatomy and Physiology?

As your study throughout higher education becomes more specific, and especially if you choose to study medical sciences, you will have to further your exploration into anatomy and physiology. The study of anatomy is a biological science; however, it is the specific study of the body structures of living things.The study of anatomy is typically broken into three subset areas of study:

• Gross Anatomy
• Microscopic Anatomy
• Physiology

Gross anatomy is the highly specialized study of the human body. During this study, the human body is completely studied and dissected. Gross anatomy is usually associated with medical school.

Microscopic anatomy further studies the cells, tissues and organs of the human body. This is a highly specialized area within the biological study of anatomy.

Physiology is a further study of the normal functions within the body. Typically, students in medical school will take both anatomy and physiology as the content in both studies are interrelated. The study of physiology includes furthering the understanding of organs, anatomy and cells and how these systems work together.

What’s the Difference Between Biology and Anatomy?

While anatomy and physiology are both biological sciences, they are not the same as general biology. It is important to understand the differences between biology and anatomy and physiology.

Biology vs. Anatomy

Biology and anatomy are interrelated, as anatomy is a subset of general biology. While students typically begin studying biology as early as elementary school, anatomy is usually not studied until college or at the post-graduate level.There are many ways these topics are related; however when you take a deeper look you will see that anatomy and biology are quite different.

Biology is the study of life including all parts and systems. Anatomy, however is the specific study of the human body. Although, in some studies such as veterinary school, students would study the anatomy of animals.

Physiology vs. Anatomy

Just as anatomy is a subset of biological science, so is physiology. However, while anatomy studies the structures of the body, physiology studies the specific body parts within the human body and how they function. Physiology studies how the different parts of the body work independently and together.

Anatomy and physiology are often taken together throughout the course of study. Both are subsets of general biology and while the specific focus of each course is different, they are interrelated. Therefore, the two courses are taken at or around the same time in the curriculum.

• Define the terms anatomy and physiology, and give specific examples to show the interrelationship between anatomy and physiology

Human Anatomy (ana- = “up”, tome = “to cut”) is often defined as the study of structures in the human body. Anatomy focuses on the description of form, or how body structures at different levels look. Gross anatomy studies macroscopic structures (for example, the body, organs, and organ systems), and histology studies microscopic structures (for example, tissues, cells, and organelles).

Human Physiology (physio = “nature”; -logy = “study”) studies the “nature” of the human body, nature in the sense of how structures at different levels work. Physiology focuses on function, or how structures at different levels work.

Anatomy and physiology are intimately related. A hand is able to grab things (function) because the length, shape, and mobility of the fingers (form) determine what things a hand can grab (function). A muscle contracts and brings bones together (function) due to the arrangement of muscles and bones, and the arrangement of organelles inside of muscle cells (form) determines how much and for how long a muscle can contract (function).

Body structure functions depend on their form. The way structures work depend on the way they are organized. So understanding Physiology requires an understanding of Anatomy, and vice versa.

Concepts, Terms, and facts check

Study Questions Write your answer in a sentence form (do not answer using loose words)

1. What is anatomy?
2. What is gross anatomy?
3. What is histology?
4. What is physiology?

Physiology Definition

Physiology is the study of all the physical and chemical processes that take place in organisms in order for them to perform all the functions and activities associated with living. Physiology can be studied at the molecular level all the way up to the level of entire organisms, and includes everything in between like cells, tissues, organs, and body systems. It involves studying how the different parts of the body work, separately and together, to allow an organism to function properly.

History of Physiology

The modern-day field of physiology has its roots in ancient cultures such as those of India, Egypt, and Greece. The Ancient Greek philosopher Hippocrates believed that the body contained four important fluids called the “four humors”: phlegm, blood, yellow bile, and black bile. He believed that if there was any disturbance in the amounts of these fluids in the body and their ratios to each other, a person would suffer from ill health. For example, too much yellow bile was thought to cause anger, irritability, and jealousy, while too much black bile was associated with being depressed, pessimistic, and withdrawn. These ideas were used in medicine from around 420 B.C. all the way until the 1800s.

In 1838, there was a paradigm shift when Matthias Schleiden and Theodor Schwann developed cell theory, which hypothesized that the body was made up of billions of individual cells. This theory was developed through the use of the compound microscope, a tool that became widespread in the 19 th century and allowed for the advancement of many types of scientific knowledge. From that point on, scientists began to study physiology mainly in the context of cells, tissues, organs, and body systems. Specialized branches such as gastric physiology and cell physiology arose.

The importance of physiology was reflected in Nobel Prize, which began to be offered in the category of Physiology or Medicine in 1901. The first Nobel Prize in Physiology or Medicine was awarded to Emil von Behring, who performed pioneering research on treating diphtheria and tetanus. He injected healthy animals with weakened forms of the bacteria that caused these diseases, and their immune responses made the bacterial toxins harmless. He then transferred this blood serum into infected animals. The infected animals’ symptoms were treated, and it prevented them from dying of the diseases. Eventually, this was performed in humans and saved thousands of lives. This is just one example of the groundbreaking physiology advances that took place during the past 200 years. Today, a main focus of physiology is on the pathology and treatment of diseases at the cellular and molecular level, including diseases such as cardiovascular disease, diabetes, and cancers, along with immune responses. Research is carried out on a wide range of organisms, from bacteria to plants and fungi to animals including humans.

Types of Physiology

There are many different types of physiology; the following is a small subset to show the diversity of the field.

Cell physiology: researchers study how cells carry out their processes and interact with each other. Two areas of interest include how molecules are transported across the cell membrane and how neurons transmit electrical impulses. Developmental physiology: looks at how physiology changes during embryonic development and also across the lifespan of an organism. Evolutionary physiology: looks at how physiology has changed over many generations through evolution. It can incorporate behavior, sexual selection, and changes based on geographic range, among other factors. Systems physiology (also known as systems biology): this subfield emerged in the 1990s. It is the mathematical modeling of biological systems, and often focuses on components such as metabolism and cell-to-cell signaling. Researchers use computational models to better understand biological processes. Exercise physiology: the study of the processes that occur in the body during physical exercise. It also looks at the effects of exercise, some of which are long-term.

Physiology is closely related to anatomy because it is necessary to understand anatomy in order to study the physiology of specific body parts. This is a diagram of the human lung and its surrounding muscles.

Physiology Major

People that are interested in physiology can major specifically in physiology when they are undergraduates at certain universities. However, relatively few schools offer physiology Bachelor’s degrees. Many people instead major in biology or chemistry and then go on for further schooling in physiology. Those who receive a Bachelor’s degree in any of these subjects and want to be involved in the field of physiology often go on for additional schooling. They may go to graduate school, where they will do research, teach physiology to undergraduates, complete a thesis, and ultimately get a PhD or Master’s degree. A PhD is necessary in order to be a professor at a university. Many professors teach and carry out research. Other students may go on to further schooling for a career in healthcare. For example, they may go to medical school, dental school, or veterinary school. Still others may go on to become a pharmacist, physical therapist, or physician assistant, all of which require additional training.

As for the physiology major itself, the courses are similar to courses in the biology major, but with a special emphasis on physiology. Physiology majors start their undergraduate career by taking general biology classes and laboratories, and then move on to take more specific classes focusing on anatomy and physiology of bodily systems like the cardiovascular, respiratory, or immune systems. They also take classes in chemistry, mathematics, and physics, which are often taken by biology majors (and are required for medical school). Other courses taken may include endocrinology, biochemistry, genetics, cell biology, and neurobiology.

Anatomy and Physiology 1.2 Structural Organization of the Human Body

Table of contents

Table of contents

Unit 1: Levels of Organization

1 An Introduction to the Human Body

2 The Chemical Level of Organization

3 The Cellular Level of Organization

4 The Tissue Level of Organization

Unit 2: Support and Movement

5 The Integumentary System

6 Bone Tissue and the Skeletal System

7 Axial Skeleton

8 The Appendicular Skeleton

10 Muscle Tissue

11 The Muscular System

Unit 3: Regulation, Integration, and Control

12 The Nervous System and Nervous Tissue

13 Anatomy of the Nervous System

14 The Somatic Nervous System

15 The Autonomic Nervous System

16 The Neurological Exam

17 The Endocrine System

Unit 4: Fluids and Transport

18 The Cardiovascular System: Blood

19 The Cardiovascular System: The Heart

20 The Cardiovascular System: Blood Vessels and Circulation

21 The Lymphatic and Immune System

Unit 5: Energy, Maintenance, and Environmental Exchange

22 The Respiratory System

23 The Digestive System

24 Metabolism and Nutrition

25 The Urinary System

26 Fluid, Electrolyte, and Acid-Base Balance

Unit 6: Human Development and the Continuity of Life

27 The Reproductive System

28 Development and Inheritance

Before you begin to study the different structures and functions of the human body, it is helpful to consider its basic architecture; that is, how its smallest parts are assembled into larger structures. It is convenient to consider the structures of the body in terms of fundamental levels of organization that increase in complexity: subatomic particles, atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms and biosphere (Figure 1.3).

The Levels of Organization

To study the chemical level of organization, scientists consider the simplest building blocks of matter: subatomic particles, atoms and molecules. All matter in the universe is composed of one or more unique pure substances called elements, familiar examples of which are hydrogen, oxygen, carbon, nitrogen, calcium, and iron. The smallest unit of any of these pure substances (elements) is an atom. Atoms are made up of subatomic particles such as the proton, electron and neutron. Two or more atoms combine to form a molecule, such as the water molecules, proteins, and sugars found in living things. Molecules are the chemical building blocks of all body structures.

A cell is the smallest independently functioning unit of a living organism. Even bacteria, which are extremely small, independently-living organisms, have a cellular structure. Each bacterium is a single cell. All living structures of human anatomy contain cells, and almost all functions of human physiology are performed in cells or are initiated by cells.

A human cell typically consists of flexible membranes that enclose cytoplasm, a water-based cellular fluid together with a variety of tiny functioning units called organelles . In humans, as in all organisms, cells perform all functions of life. A tissue is a group of many similar cells (though sometimes composed of a few related types) that work together to perform a specific function. An organ is an anatomically distinct structure of the body composed of two or more tissue types. Each organ performs one or more specific physiological functions. An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body.

This book covers eleven distinct organ systems in the human body (Figure 1.4 and Figure 1.5). Assigning organs to organ systems can be imprecise since organs that “belong” to one system can also have functions integral to another system. In fact, most organs contribute to more than one system.

The organism level is the highest level of organization. An organism is a living being that has a cellular structure and that can independently perform all physiologic functions necessary for life. In multicellular organisms, including humans, all cells, tissues, organs, and organ systems of the body work together to maintain the life and health of the organism.

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The word ‘anatomy‘ means ‘structure‘, while ‘physiology‘ refers to ‘function‘. We can elaborate by saying that anatomy is the detailed study of different body parts, their organization, and their interrelationship, but how these body parts and organs play their specific role in a coordinated manner is termed as physiology.

An understanding of these terms is not only beneficial to health professionals and their career; instead, it helps us know about your own body and its wellness. Familiarity with the body (physiology and anatomy) of living beings make us aware of the healthful choices, and it also makes us aware of taking appropriate action against the signs arising during any illness.

The knowledge related to anatomy and physiology will also help in making you understand the information related to medical devices, various treatments, procedures, nutrition, and medications and of course the multiple infectious and genetic disease.

These subjects are studied together and are incomplete without each other. As understanding anatomy without knowing the physiology is worthless, vice versa is also true that knowing anatomy is critical before getting knowledge of physiology. So, in this article, we will provide an overview of anatomy as well as physiology and the points on which they differentiate.

Content: Anatomy Vs Physiology

Comparison Chart

Basis for Comparison	Anatomy	Physiology
Meaning	Anatomy is the concept that deals with the study of structure like muscles, bones and interior organs of the body. It is the kind of static research.	Physiology is the concepts that deal with the study of functions of different organs like digestion, respiration, reproduction, osmoregulation, etc. It is considered to be a dynamic study.
Can be performed in	Anatomy can be analysed in dead as well as living beings.	Physiology is analysed in the living being only.
Deals with	Anatomy deals with the body’s structure, different parts like cells, tissues, organs and organ system, etc.	Physiology deals with the working of the body’s part and their specific roles.
Importance	The understanding of the anatomy of a living organism is vital to know about every part of the body.	The understanding of the physiology of a living organism is essential to know the function of every organ of the body.
Example	Anatomy of the heart means, the structure of the heart, its chambers, arteries, veins, the valves, etc.	Physiology means how the pumping of the blood is done by heart.

Definition of Anatomy

Anatomy is the Greek word that means “to cut apart”. The scientific study of any living body’s structure is known as anatomy, while the study of the human body’s structure is known as Human anatomy. There are various types of structures, shapes, and sizes present in our body, few of them can be observed easily, while few are analyzed with the help of a microscope.

Human anatomy came into existence while observing the wounds and injuries of the soldiers and exterior of the bodies. Later on, the physicians were allowed to study and gain knowledge about human body structure by dissecting their dead bodies. For analyzing the body’s internal parts, it is dissected, and structures are cut apart, and then these parts are observed which also provide information that how they are interrelated and work in a coordinated manner.

Dissection is still performed in medical institution and in pathology labs, to study and observe every structure of the human body, however with the advancing technology numerous imaging techniques have been developed to analyze the internal structure. X-rays, CT Scan, Ultrasound, etc. are such techniques that allow clinicians or medical professionals to visualize the internal structures of the living body like fractured bones, internal injuries or cancerous tumour.

Anatomy is studied under two area of specialization: Macroscopic anatomy and Microscopic anatomy. Macroscopic anatomy is a study of such an arrangement of the body that is noticeable without the use of a microscope or any magnification. Microscopic anatomy includes the study of the cells (cytology), and tissue (histology) and other tiny or smaller structure that is only visible with the microscope or any different kind of magnification.

There are two conventional approaches to study the structure of the body: regional and systemic. Regional anatomy deals with the study of relationships between the different structures present in the specific region of the body like the abdomen. Regional anatomy helps us to understand how the cells, nerves, tissues, blood vessels and other structures function together with the target of serving the particular body area properly.

Systemic anatomy is the study of groups of structures that work together for performing the specialized function. For example, the study of the muscular system would include all the skeletal muscles of the body.

Definition of Physiology

The study of the organization of structures of the body and their working which counterpart other organs to function together with the aim of supporting the functions of life is known as physiology. The study of physiology focuses mainly on homeostasis, which is the ability to maintain constant internal condition by living things.

Physiology is the observations of pathologic conditions of the organs and its functioning. It deals with terms like cardiovascular, respiratory, urogenital, etc. Physiology has many subspecialties as it deals with all the critical process going within our body throughout life.

Key Differences Between Anatomy and Physiology

Following are the essential differences between the terms anatomy and physiology:

1. Anatomy is the kind of static study that deals with the observation of internal as well as external structures of the body. Physiology is considered as the dynamic concepts that deal with the study of functions of different organs like digestion, respiration, reproduction, osmoregulation, etc.
2. Anatomy can be analyzed in dead as well as living beings, but physiology is analyzed in the living being only.
3. Anatomy deals with the body’s structure, different parts like cells, tissues, organs and organ system, etc., whereas physiology deals with the working of the body’s part and their specific roles.
4. If we are discussing the anatomy of the heart, it means we are observing the structure of the heart, its chambers, arteries, veins, the valves, etc., while physiology oh heart means how the pumping of the blood is done by heart.

Conclusion

Anatomy and Physiology are closely related concepts that are studied together. In other words, anatomy is the analysis of an organism and how it is organized internally as well as externally, whereas physiology is how these organs function usually.

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Metabolism and Nutrition

Absorption of Macronutrients
Absorption of water: Water and electrolyte ions (Na+, Ca2+, Cl-) move across the intestinal epithelial cells by passive diffusion and are absorbed into the bloodstream.

Absorption of nutrient molecules: Glucose and the other simple sugars are transported across the intestinal epithelial cells by a GLUT transporter. This is a sodium dependent transporter that binds sodium then glucose and transports them inside the cell. Amino acids are transported across the intestinal epithelial cells by four sodium dependent amino acid transporters.

Metabolism
Carbohydrate metabolism: As glucose and fructose are absorbed in the small intestine, they are first brought to the liver via the portal vein. Depending on the needs of the body, the liver will either store excess glucose as glycogenВ (glycogenesis) or breakdown glycogen to release glucose into the bloodstream (glycogenolysis).

Protein metabolism: Proteins are digested and absorbed as amino acids. Amino acids can be used inside cells to build proteins, or can be catabolized and used for producing energy.

Lipid metabolism: Lipids are stored in the body as triglycerides, and when they are mobilized for energy they are released as free fatty acids (FFA).

Energy Production
Glycolysis: Glycolysis is a pathway in which a molecule of glucose is oxidized into two molecules of pyruvic acid. Glycolysis takes place in the cytosol of the cell.

Citric Acid Cycle: The Citric Acid Cycle, also known as the Krebs Cycle, converts Acetyl CoA into NADH and FADH2, which are coenzymes that transfer electrons during the last step in energy production.

Oxidative phosphorylation: Nutrient molecules contain stored energy; enzymes perform oxidation-reduction reactions to facilitate the formation of adenosine triphosphate (ATP).

ATP production: During the process of electron transport, electrons from NADH and FADH2 are passed through the chain, which leads to protons (H+) being pumped into the intermembrane space in the mitochondria. The energy of the proton gradient is used to drive the energy consuming reaction ADP converted into ATP.

Regulation of Metabolism

Absorptive state: Absorptive state: during this state the majority of glucose absorbed from the gastrointestinal tract is converted to glycogen and triglycerides.

Postabsorptive state: the main goal of the body during this state is to maintain a normal blood sugar level. In order to do this, glucose is released from glycogen, and triglycerides are converted into free fatty acids. Glycerol is oxidized into energy, in the form of ATP.

Hormonal regulation of metabolism: The main hormones that regulate metabolism in the body are: (A) insulin (B) glucagon and (C) epinephrine.

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After the nutrient molecules are digested in the stomach and the small intestine they must be absorbed into the bloodstream. The nutrient molecules are then catabolized into key precursor molecules necessary for the cell to make ATP for the cellular energy.

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Specific Tutorial Features: The steps of nutrient molecule absorption into the bloodstream and then the conversion of these into cellular ATP are presented. Concept map showing inter-connections of new concepts in this tutorial and those previously introduced. Definition slides introduce terms as they are needed. Visual representation of concepts Examples given throughout to illustrate how the concepts apply. A concise summary is given at the conclusion of the tutorial.

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Absorption of Macronutrients Absorption of water Absorption of nutrient molecules Carbohydrate metabolism Protein metabolism Lipid metabolism Citric Acid Cycle Oxidative phosphorylation ATP production Regulation of Metabolism Absorptive state Postabsorptive state Hormonal regulation of metabolism See all 24 lessons in Anatomy and Physiology, including concept tutorials, problem drills and cheat sheets: Teach Yourself Anatomy and Physiology Visually in 24 Hours Send a gift of education to someone you care. Give the learning edge with our rapid learning courses. Product Code RL-700-GP Premium RL-700-GS Standard RL-700-GL Lite

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The Digestive System

Ingestion and Swallowing: Swallowing is a complex event that is coordinated by the swallowing center in the lower portion of the brainstem. During this process, food passes from the mouth to the pharynx and into the esophagus.

Oral phase: initially, the food bolus is moved to the back of the tongue. This triggers swallowing, by stimulating touch receptors in the pharynx. Then, the anterior of the tongue lifts to the hard palate and forces the bolus to the pharynx.

Pharyngeal phase: during the pharyngeal phase, the larynx is pulled forward and upward under the tongue by muscular contraction. As the larynx rises, the epiglottis moves backwards and downwards to seal off the glottis (the entrance to the respiratory system).

Esophageal phase: during the esophageal phase, the food bolus is pushed through the esophagus by involuntary muscle contractions called peristalsis.

Stomach: The stomach is a J-shaped organ, directly under the diaphragm. The uperior portion is a continuation of the esophagus. The inferior portion (pylorus) empties the stomach contents into the first segment of the small intestine.

Gastric juices: The main component of gastric juices released during digestion is gastric acid. Gastric acid is hydrochloric acid produced by the parietal cells, and it makes the lumen of the stomach very acidic with a pH of 2-3. This increased acidity contributes both to the conversion of pepsinogen to pepsin and to the breakdown of foods.

Liver and Gallbladder
Bile production and storage: The liver is involved in many aspects of nutrient metabolism, and the regulation of the products of digestion in the blood: (A) Carbohydrate metabolism, (B) Protein and lipid metabolism and (C) Vitamin storage.

Bile is an alkaline fluid produced by hepatocytes in the liver, and it helps to emulsify fats during digestion and absorption in the small intestine. Bile contains taurocholic and deoxycholic salts; these salts combine with fat globules and break them down into small droplets for absorption in the small intestine.

Pancreas
Structure: The pancreas is an elongated organ, adjacent to the stomach and in close association with the first segment of the small intestine, the duodenum.

Digestive enzymes: The pancreas produces a number of enzymes used in the process of digestion: (a) trypsinogen and chymotrypsinogen, (b) pancreatic lipase and (c) amylase.

Small Intestine: The small intestine is 8-22 ft. in length in an adult; it is divided into three main segments: duodenum, jejunum and the ileum. The small intestine is the site were most of the nutrients from digested food takes place.

Large Intestine: The large intestine is shorter in length (4-5 ft) than the small intestine, but it is so named because of its increased diameter. The large intestine is divided into four major areas: the ascending, transverse, descending and sigmoid colon.

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Food must be ingested and digested so the resultant nutrient molecules can be absorbed in the intestines. As food passes through the mouth and into the stomach, stomach acid and enzymes in the stomach break it down. This process continues in the small intestine where the nutrient molecules themselves are absorbed.

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Ingestion and Swallowing Oral phase Pharyngeal phase Esophageal phase Gastric juices Liver and Gallbladder Bile production and storage See all 24 lessons in Anatomy and Physiology, including concept tutorials, problem drills and cheat sheets: Teach Yourself Anatomy and Physiology Visually in 24 Hours Anatomy and Physiology 1.1 Overview of Anatomy and Physiology Table of contents Table of contents Unit 1: Levels of Organization 1 An Introduction to the Human Body 2 The Chemical Level of Organization 3 The Cellular Level of Organization 4 The Tissue Level of Organization Unit 2: Support and Movement 5 The Integumentary System 6 Bone Tissue and the Skeletal System 7 Axial Skeleton 8 The Appendicular Skeleton 10 Muscle Tissue 11 The Muscular System Unit 3: Regulation, Integration, and Control 12 The Nervous System and Nervous Tissue 13 Anatomy of the Nervous System 14 The Somatic Nervous System 15 The Autonomic Nervous System 16 The Neurological Exam 17 The Endocrine System Unit 4: Fluids and Transport 18 The Cardiovascular System: Blood 19 The Cardiovascular System: The Heart 20 The Cardiovascular System: Blood Vessels and Circulation 21 The Lymphatic and Immune System Unit 5: Energy, Maintenance, and Environmental Exchange 22 The Respiratory System 23 The Digestive System 24 Metabolism and Nutrition 25 The Urinary System 26 Fluid, Electrolyte, and Acid-Base Balance Unit 6: Human Development and the Continuity of Life 27 The Reproductive System 28 Development and Inheritance Human anatomy is the scientific study of the body’s structures. Some of these structures are very small and can only be observed and analyzed with the assistance of a microscope. Other larger structures can readily be seen, manipulated, measured, and weighed. The word “anatomy” comes from a Greek root that means “to cut apart.” Human anatomy was first studied by observing the exterior of the body and observing the wounds of soldiers and other injuries. Later, physicians were allowed to dissect bodies of the dead to augment their knowledge. When a body is dissected, its structures are cut apart in order to observe their physical attributes and their relationships to one another. Dissection is still used in medical schools, anatomy courses, and in pathology labs. In order to observe structures in living people, however, a number of imaging techniques have been developed. These techniques allow clinicians to visualize structures inside the living body such as a cancerous tumor or a fractured bone. Like most scientific disciplines, anatomy has areas of specialization. Gross anatomy is the study of the larger structures of the body, those visible without the aid of magnification (Figure 1.2 a). Macro- means “large,” thus, gross anatomy is also referred to as macroscopic anatomy. In contrast, micro- means “small,” and microscopic anatomy is the study of structures that can be observed only with the use of a microscope or other magnification devices (Figure 1.2 b). Microscopic anatomy includes cytology, the study of cells and histology, the study of tissues. As the technology of microscopes has advanced, anatomists have been able to observe smaller and smaller structures of the body, from slices of large structures like the heart, to the three-dimensional structures of large molecules in the body. Anatomists take two general approaches to the study of the body’s structures: regional and systemic. Regional anatomy is the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. Studying regional anatomy helps us appreciate the interrelationships of body structures, such as how muscles, nerves, blood vessels, and other structures work together to serve a particular body region. In contrast, systemic anatomy is the study of the structures that make up a discrete body system—that is, a group of structures that work together to perform a unique body function. For example, a systemic anatomical study of the muscular system would consider all of the skeletal muscles of the body. Whereas anatomy is about structure, physiology is about function. Human physiology is the scientific study of the chemistry and physics of the structures of the body and the ways in which they work together to support the functions of life. Much of the study of physiology centers on the body’s tendency toward homeostasis. Homeostasis is the state of steady internal conditions maintained by living things. The study of physiology certainly includes observation, both with the naked eye and with microscopes, as well as manipulations and measurements. However, current advances in physiology usually depend on carefully designed laboratory experiments that reveal the functions of the many structures and chemical compounds that make up the human body. Like anatomists, physiologists typically specialize in a particular branch of physiology. For example, neurophysiology is the study of the brain, spinal cord, and nerves and how these work together to perform functions as complex and diverse as vision, movement, and thinking. Physiologists may work from the organ level (exploring, for example, what different parts of the brain do) to the molecular level (such as exploring how an electrochemical signal travels along nerves). Form is closely related to function in all living things. For example, the thin flap of your eyelid can snap down to clear away dust particles and almost instantaneously slide back up to allow you to see again. At the microscopic level, the arrangement and function of the nerves and muscles that serve the eyelid allow for its quick action and retreat. At a smaller level of analysis, the function of these nerves and muscles likewise relies on the interactions of specific molecules and ions. Even the three-dimensional structure of certain molecules is essential to their function. Your study of anatomy and physiology will make more sense if you continually relate the form of the structures you are studying to their function. In fact, it can be somewhat frustrating to attempt to study anatomy without an understanding of the physiology that a body structure supports. Imagine, for example, trying to appreciate the unique arrangement of the bones of the human hand if you had no conception of the function of the hand. Fortunately, your understanding of how the human hand manipulates tools—from pens to cell phones—helps you appreciate the unique alignment of the thumb in opposition to the four fingers, making your hand a structure that allows you to pinch and grasp objects and type text messages. You’re probably reading this article because you want to know how to study anatomy in the easiest, quickest and most pain-free manner. Well, good news – you’ve come to the right place! Anatomy learning resources: Choosing the right one You may have already spent some time looking at different anatomy learning resources and found yourself feeling overwhelmed by the sheer number of options. Indeed, deciding on the resource(s) you’ll use to learn can be more stressful than learning itself! In this section, we’re going to walk you through the most common anatomy learning resources, as well as the pros and cons of each. Hopefully this will make it easier for you to decide on the right one for you and your needs. University lectures, seminars and labs Of course, if you’re studying anatomy as part of your school or university course, there’s not much getting away from lectures, seminars and laboratories. For those of you to whom this applies, these resources will likely provide the foundation for your anatomy studies. Unfortunately, for most students faced with the task of learning copious amounts of anatomy, these resources are not sufficient alone.It can be difficult to understand the different structures and connections between them when viewing a cadaver. And in some cases, professors will only cover certain topics, leaving the onus on you to go and learn everything else in your spare time. In other cases, you might not understand or connect with a particular professor’s teaching approach. This can leave you feeling stressed and discouraged. Anatomy atlas textbooks The most common anatomy learning resource is no doubt an anatomy atlas. This can be thought of as an anatomy students’ bread and butter. There are two main options here. You can choose to use an online anatomy atlas, like the one here at Kenhub. Or, you can take the traditional route and buy a physical, paper atlas. The problem with a physical atlas is that it tends to be very expensive, and not very engaging to read and learn from. However, some students find them effective. We’ve written balanced reviews of several of the most commonly used anatomy atlases on the market. If you’re thinking about purchasing one, check the reviews out below. The digestive system includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body. Food is broken down, bit by bit, until the molecules are small enough to be absorbed and the waste products are eliminated. The digestive tract, also called the alimentary canal or gastrointestinal (GI) tract, consists of a long continuous tube that extends from the mouth to the anus. It includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. The tongue and teeth are accessory structures located in the mouth. The salivary glands, liver, gallbladder, and pancreas are major accessory organs that have a role in digestion. These organs secrete fluids into the digestive tract. Food undergoes three types of processes in the body: Digestion and absorption occur in the digestive tract. After the nutrients are absorbed, they are available to all cells in the body and are utilized by the body cells in metabolism. The digestive system prepares nutrients for utilization by body cells through six activities, or functions. Ingestion The first activity of the digestive system is to take in food through the mouth. This process, called ingestion, has to take place before anything else can happen. Mechanical Digestion The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach. Chemical Digestion The complex molecules of carbohydrates, proteins, and fats are transformed by chemical digestion into smaller molecules that can be absorbed and utilized by the cells. Chemical digestion, through a process called hydrolysis, uses water and digestive enzymes to break down the complex molecules. Digestive enzymes speed up the hydrolysis process, which is otherwise very slow. Movements After ingestion and mastication, the food particles move from the mouth into the pharynx, then into the esophagus. This movement is deglutition, or swallowing. Mixing movements occur in the stomach as a result of smooth muscle contraction. These repetitive contractions usually occur in small segments of the digestive tract and mix the food particles with enzymes and other fluids. The movements that propel the food particles through the digestive tract are called peristalsis. These are rhythmic waves of contractions that move the food particles through the various regions in which mechanical and chemical digestion takes place. Absorption The simple molecules that result from chemical digestion pass through cell membranes of the lining in the small intestine into the blood or lymph capillaries. This process is called absorption. Elimination The food molecules that cannot be digested or absorbed need to be eliminated from the body. The removal of indigestible wastes through the anus, in the form of feces, is defecation or elimination. Enzymes Of Health And Industry Honors Chemistry 5 May, 2017 Enzymes in Health and Industry Without enzymes life would not be the same. We need enzymes for almost every chemical reaction that occurs in our bodies. Many industries rely on enzymes to help in their industrial chemical processes. Without enzymes we wouldn’t have cheese, detergent, or bread. We wouldn’t be able to drink milk or digest our food. Enzymes are often a forgotten part of our daily lives, but we couldn’t live without enzymes. Enzymes are natural catalysts that The Gastrointestinal System For An Intake Of Substance And Extracts The Nutrients From Food substance that is not absorbed by the body is then expelled as waste (Wallace 2013). The Gastrointestinal System starts at the mouth primarily with mechanical digestion. It then follows a hollow tube called the esophagus, which serves as a connecter into the stomach. The stomach continues to mechanically churn the bolus, but also takes part in the chemical breakdown of proteins (Bolus 2016). From the stomach the chyme enters into the small intestine. The small intestine is comprised of three sections: the Process Of A Bolus Of Food Entering And Exiting The Human Via The Digestive System Student Discussion Assignment Trace and discuss the complete movement of a bolus of food entering and exiting the human via the digestive system. The process of digestion first begins in the mouth by in taking food (bolus). The teeth help with masticating (chewing and breaking food particles down) allowing for swallowing and increasing surface area for chemical digestion. Enzymes found in saliva also facilitates with the chemical break down of food primarily starches and fats. The food swallowed Anatomical Features Of Anatomy And Anatomy Physiology and anatomy are the two main terms in accordance with study of the human body or living matter. Physiology is defined as the study of how living organisms function, including processes such as movement, nutrition and reproduction. Anatomy is study of the structure of a living organism and all the components; including cells, tissue and organs. (St. Patrick’s, 2017). In response to task 1 I have created a table illustrating each of the 10 body systems and their main anatomical features Unit 4.2 Body Systems in Relation to Energy Metabolism in the Body M1-Discuss the Roles of Energy in the Body In this assignment I will be explaining the physiology of the cardiovascular system and the respiratory system. Whilst explaining the two body systems I will be explaining energy production, process of cellular respiration, the role of enzymes within these body systems, the way that these systems absorb food and the products of digestion. The Cardiovascular System The heart pumps the blood Digestive System Study Guide Essay Digestive System Study Guide 1. Define the term digestion and explain its significance. The chemical and mechanical process of breaking down food and its absorption. Its essential to maintaining life. 2. Distinguish between mechanical digestion and chemical digestion. Chemical digestion is where complex food molecules are broken down to the basic building blocks by enzymes. Mechanical digestion is chewing, churning and segmentation. 3. Discuss the five digestive processes that overview the many functions Energy Metabolism: Cardiovascular and Digestive Systems Task 4 (P4) P4: Explain the physiology of two named body systems in relation to energy metabolism in the body In your role as a health and social care professional in a respite care home you have been asked to prepare a booklet to explain to your client group how the body requires and uses energy. You should produce an information booklet that gives an overview of how energy is produced and utilised in the body. You booklet should include information on: * Energy forms * Energy M1,M2, M3 Anatomy and Physiology M1. Discuss the role of energy in the body The three systems in our body that work together are cardiovascular, respiratory and digestive systems which supply energy to the cells of the body. I will be describing their role of energy in the body system; also I am going to explain the physiology of the three named body systems in relation to energy metabolism. Respiratory System The respiratory system consists of tissues and organs in our body which are formed into groups. The system includes airways Physio Ex Exp 8 Chemical and Physical Processes of Digestion exercise T 8 he digestive system is a physiological marvel, composed of finely orchestrated chemical and physical activities. The food we ingest must be broken down to its molecular form for us to get the nutrients we need, and digestion involves a complex sequence of mechanical and chemical processes designed to achieve this goal as efficiently as possible. As food passes through the gastrointestinal tract, it is progressively broken down NR228 Digestion Start at the beginning and discuss the anatomical parts as well as the biochemical roles that contribute to this sandwich being turned into chemical energy. Be sure to include mechanical and chemical mechanisms, along with how they are metabolized in the body! Digestion is the chemical breakdown of food molecules into smaller molecules that can be used by various cells within the body. The breakdown is initiated when food is ingested in the mouth and specific enzymes are exposed to components within Figure 1. Blood Pressure. A proficiency in anatomy and physiology is fundamental to any career in the health professions. (Credit: Bryan Mason/flickr) Though you may approach a course in anatomy and physiology strictly as a requirement for your field of study, the knowledge you gain in this course will serve you well in many aspects of your life. An understanding of anatomy and physiology is not only fundamental to any career in the health professions, but it can also benefit your own health. Familiarity with the human body can help you make healthful choices and prompt you to take appropriate action when signs of illness arise. Your knowledge in this field will help you understand news about nutrition, medications, medical devices, and procedures and help you understand genetic or infectious diseases. At some point, everyone will have a problem with some aspect of his or her body and your knowledge can help you to be a better parent, spouse, partner, friend, colleague, or caregiver. This chapter begins with an overview of anatomy and physiology and a preview of the body regions and functions. It then covers the characteristics of life and how the body works to maintain stable conditions. It introduces a set of standard terms for body structures and for planes and positions in the body that will serve as a foundation for more comprehensive information covered later in the text. It ends with examples of medical imaging used to see inside the living body. Body Functions Body functions are the physiological or psychological functions of body systems. The body’s functions are ultimately its cells’ functions. Survival is the body’s most important business. Survival depends on the body’s maintaining or restoring homeostasis, a state of relative constancy, of its internal environment. More than a century ago, French physiologist, Claude Bernard (1813-1878), made a remarkable observation. He noted that body cells survived in a healthy condition only when the temperature, pressure, and chemical composition of their environment remained relatively constant. Later, an American physiologist, Walter B. Cannon (1871-1945), suggested the name homeostasis for the relatively constant states maintained by the body. Homeostasis is a key word in modern physiology. It comes from two Greek words – “homeo,” meaning the same, and “stasis,” meaning standing. “Standing or staying the same” then is the literal meaning of homeostasis. However, as Cannon emphasized, homeostasis does not mean something set and immobile that stays exactly the same all the time. In his words, homeostasis “means a condition that may vary, but which is relatively constant.” Homeostasis depends on the body’s ceaselessly carrying on many activities. Its major activities or functions are responding to changes in the body’s environment, exchanging materials between the environment and cells, metabolizing foods, and integrating all of the body’s diverse activities. The body’s ability to perform many of its functions changes gradually over the years. In general, the body performs its functions least well at both ends of life – in infancy and in old age. During childhood, body functions gradually become more and more efficient and effective. During late maturity and old age the opposite is true. They gradually become less and less efficient and effective. During young adulthood, they normally operate with maximum efficiency and effectiveness. Life Process All living organisms have certain characteristics that distinguish them from non-living forms. The basic processes of life include organization, metabolism, responsiveness, movements, and reproduction. In humans, who represent the most complex form of life, there are additional requirements such as growth, differentiation, respiration, digestion, and excretion. All of these processes are interrelated. No part of the body, from the smallest cell to a complete body system, works in isolation. All function together, in fine-tuned balance, for the well being of the individual and to maintain life. Disease such as cancer and death represent a disruption of the balance in these processes. The following are a brief description of the life process: Organization At all levels of the organizational scheme, there is a division of labor. Each component has its own job to perform in cooperation with others. Even a single cell, if it loses its integrity or organization, will die. Metabolism Metabolism is a broad term that includes all the chemical reactions that occur in the body. One phase of metabolism is catabolism in which complex substances are broken down into simpler building blocks and energy is released. Responsiveness Responsiveness or irritability is concerned with detecting changes in the internal or external environments and reacting to that change. It is the act of sensing a stimulus and responding to it. Movement There are many types of movement within the body. On the cellular level, molecules move from one place to another. Blood moves from one part of the body to another. The diaphragm moves with every breath. The ability of muscle fibers to shorten and thus to produce movement is called contractility. Reproduction For most people, reproduction refers to the formation of a new person, the birth of a baby. In this way, life is transmitted from one generation to the next through reproduction of the organism. In a broader sense, reproduction also refers to the formation of new cells for the replacement and repair of old cells as well as for growth. This is cellular reproduction. Both are essential to the survival of the human race. Growth Growth refers to an increase in size either through an increase in the number of cells or through an increase in the size of each individual cell. In order for growth to occur, anabolic processes must occur at a faster rate than catabolic processes. Differentiation Differentiation is a developmental process by which unspecialized cells change into specialized cells with distinctive structural and functional characteristics. Through differentiation, cells develop into tissues and organs. Respiration Respiration refers to all the processes involved in the exchange of oxygen and carbon dioxide between the cells and the external environment. It includes ventilation, the diffusion of oxygen and carbon dioxide, and the transport of the gases in the blood. Cellular respiration deals with the cell’s utilization of oxygen and release of carbon dioxide in its metabolism. Digestion Digestion is the process of breaking down complex ingested foods into simple molecules that can be absorbed into the blood and utilized by the body. Excretion Excretion is the process that removes the waste products of digestion and metabolism from the body. It gets rid of by-products that the body is unable to use, many of which are toxic and incompatible with life. The ten life processes described above are not enough to ensure the survival of the individual. In addition to these processes, life depends on certain physical factors from the environment. These include water, oxygen, nutrients, heat, and pressure. 1. Which group of major parts and organs make up the immune system? A. lymphatic system, spleen, tonsils, thymus, and bone marrow B. brain, spinal cord, and nerve cells C. heart, veins, arteries, and capillaries D. nose, trachea, bronchial tubes, lungs, and alveolus 2. Which of the following is an example of a tissue? A. chloroplast B. liver C. mammal D. hamstring 3. The adrenal glands are part of the: A. immune system. B. endocrine system. C. lymphatic system. D. respiratory system. 4. Which hormone is produced by the pineal gland? A. insulin B. testosterone C. melatonin D. epinephrine 5. How many organ systems are there in the human body? 6. The brain is part of the: A. integumentary system. B. nervous system. C. endocrine system. D. respiratory system. 7. How many basic tissue types does a human have? A. 4 B. 6 C. 12 D. 23 8. Of the following, the blood vessel containing the least oxygenated blood is the: A. aorta. B. vena cava. C. pulmonary artery. D. capillaries. E. femoral vein. 9. The digestion of starch begins in the: A. mouth. B. stomach. C. pylorus. D. duodenum. E. ileum. 10. During the process of oogenesis, primary oocytes produce: A. sperm. B. eggs. C. oogonia. D. stem cells. E. none of the above. Anatomy and Physiology Answers 1. A: The immune system consists of the lymphatic system, spleen, tonsils, thymus, and bone marrow. 2. A: A chloroplast is an example of tissue. A liver is an organ, a mammal is a type of organism, and a hamstring is a muscle. 3. B: The adrenal glands are part of the endocrine system. They sit on the kidneys and produce hormones that regulate salt and water balance and influence blood pressure and heart rate. 4. C: Melatonin is produced by the pineal gland. One of the primary functions of melatonin is regulation of the circadian cycle, which is the rhythm of sleep and wakefulness. Insulin helps regulate the amount of glucose in the blood. Without insulin, the body is unable to convert blood sugar into energy. Testosterone is the main hormone produced by the testes; it is responsible for the development of adult male sex characteristics. Epinephrine, also known as adrenaline, performs a number of functions, including quickening and strengthening of the heartbeat and dilation of the bronchioles. Epinephrine is one of the hormones secreted when the body senses danger. 5. C: There are 11 organ systems in the human body. 6. B: The brain is part of the nervous system. 7. A: There are four basic tissue types in humans: epithelial, connective, nervous, and muscular. 8. C: The pulmonary artery carries oxygen-depleted blood from the heart to the lungs, where CO2 is released and the supply of oxygen is replenished. This blood then returns to the heart through the pulmonary artery and is carried through the aorta and a series of branching arteries to the capillaries, where the bulk of gas exchange with the tissues occurs. Oxygen-depleted blood returns to the heart through branching veins (the femoral veins bring it from the legs) into the vena cava, which carries it again to the heart. Since the pulmonary artery is the last step before replenishment of the blood’s oxygen content, it contains the blood that is the most oxygen depleted. 9. A: The digestion of starch begins with its exposure to the enzyme amylase, which is present in saliva. Amylase attacks the glycosidic bonds in starch, cleaving them to release sugars. This is the reason why some starchy foods may taste sweet if they are chewed extensively. Another form of amylase is produced by the pancreas and continues the digestion of starches in the upper intestine. The di- and tri-saccharides, which are the initial products of this digestion, are eventually converted to glucose, a monosaccharide that is easily absorbed through the intestinal wall. 10. B: Oogenesis is the process that gives rise to the ovum, or egg, in mammals. The oocyte is the immature egg cell in the ovary. In humans, one oocyte matures during each menstrual cycle. It develops first into an intermediate form called the ootid and eventually into an ovum. The prefix oo- is derived from Greek and means “egg.” Physiology The word physiology is from the Ancient Greek φυσιολογία (phusiología, “natural philosophy”) and it is the study of how organisms perform their vital functions. An example is the study of how a muscle contracts or the force contracting muscles exert on the skeleton. It was introduced by French physician Jean Fernery in 1552. Physiology is built upon a tripod of sciences: physics, chemistry, and anatomy. Human physiology is the study of functions of the human body that can be divided into the following types: This is the cornerstone of human physiology; it is the study of the functions of cells. This is the study of the functions of specific organs. For example, renal physiology is the study of kidney function. It includes all aspects of the function of the body systems, such as cardiovascular physiology, respiratory physiology, reproductive physiology etc.. It is the study of the effects of diseases on organ or system functions (pathos is the Greek word for disease). Atom: An atom is the smallest particle of an element or a molecule. [carbon (C), Hydrogen (H), Oxygen (O), etc.]. Molecule: A molecule is a particle composed of two or more joined atoms (carbon dioxide CO2, water H2O). Macromolecule: A macromolecule is a large molecule (carbohydrates, lipids, proteins, nucleic acids). Organelles: An organelle is a small organ of a cell, which performs a particular function (cell membrane, cytoplasm and nucleus) Cell: The cell is the basic unit of structure and function of living organisms. Tissue: A tissue is a group of similar cells that perform a specialized function (epithelia, connective, muscle and nervous). Organ: An organ is a structure consisting of a group of tissues that perform a specialized function (skin, heart, brain, etc.). System: A system is a group of organs that act together to perform a specialized function. 1 . cardiovascular system 2 . respiratory system 3 . urinary system 4 . digestive system 5.nervous system 6.reproductive system 7.endocrine system 8 . musculoskeletal system 9.integument system. Human body: A living organism is the most complex level of organization. It consists of all the systems arranged in a discrete manner so as to facilitate functioning of the various organ systems in synchronicity. The seven characteristics of life 1. Cells: All living organisms have cells; cells are the building blocks of life. 2. Metabolism: All living organisms eat, drink, breathe and excrete. 3. Growth: All living organisms take in material from the environment to enlarge and sustain. 4. Reproduction: All living organisms are able to produce a copy of themselves. 5. Irritability: All living organisms are able to react to a change in their environment. 6. Adaptation: All living organisms are able to compete with each other for food and space to survive. 7. Movement: All living organisms are able to move. The cell is the basic unit of all living organisms. The cell is the functional unit of an organism. Cells are not all the same but all cells share general structures! Cells are organized into three main regions: Nucleus, cytoplasm and plasma membrane. 1) The nucleus : It is the center of the cell because it contains genetic material (DNA). It consists of three main regions: the nuclear membrane, the nucleolus and chromatin. Nuclear membrane : Nuclear membrane serves as a barrier of nucleus. It consists of a double phospholipid membrane and contains nuclear pores that allow for the exchange of material with the rest of the cell. Nucleolus : Nucleus contains one or more nucleoli. It functions as site of ribosome production. Ribosomes then migrate to the cytoplasm through nuclear pores. Chromatin : It is composed of DNA and protein scattered throughout the nucleus. Chromatin condenses to form chromosomes when the cell divides. 2) Plasma membrane : It is the barrier for cell contents. It consists of double phospholipid layer and monolayer of protein scattered around phospholipid layer. Other materials in plasma membrane such as cholesterol and glycoproteins. 3) Cytoplasm : It is a thick jelly like fluid. It represents the material outside the nucleus and inside the plasma membrane. It consists of Cytosol. Cytosol: It is a fluid that suspends other elements – organelles. Organelles: That perform the metabolic activity of the cell. Cytoplasmic organelles : These are the organelles which are present scattered into the cytoplasm and performs specific functions. These are as follows:- Ribosomes : They represent sites of protein synthesis in the cell. They are found at two locations : Free in the cytoplasm and attached to endoplasmic reticulum. Endoplasmic reticulum (ER) : They are fluid-filled tubules for carrying substances. There are two types of ER : Rough endoplasmic reticulum : They Carry ribosomes that represent sites of protein synthesis. Smooth endoplasmic reticulum : They function in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs. Golgi apparatus : It modifies and packages proteins, secrete vesicles, plasma membrane components and lysosomes. Lysosomes : They contain enzymes that digest non-usable materials within the cell. Peroxisomes : These are membranous sacs of oxidase enzymes. They detoxify harmful substances and break down free radicals. Mitochondria : They represent powerhouse of the cell. They can change shape continuously. They also carry out reactions where oxygen is used to break down food to provide ATP for cellular activities. Centrosome : The centrosome is composed of two centrioles surrounded by an amorphous mass of protein. Centrosomes are associated with the nuclear membrane during prophase of the cell cycle. In mitosis the nuclear membrane breaks down and the centrosome can interact with the chromosomes to build the mitotic spindles. Centrioles : These are self-replicating organelles made up of nine bundles of microtubules. They appear to help in organizing cell division, but aren’t essential to Cytoskeleton : It’s a network of protein structures that extend throughout the cytoplasm. It provides the cell with an internal framework. For example, microfilaments and microtubules. a-Microfilaments : Microfilaments are solid rods made of proteins called actin. These filaments are important supports of the cytoskeleton. b-Microtubules : These straight, hollow cylinders are found throughout the cytoplasm of all human cells and carry out a variety of functions, ranging from transport to structural support. Cell membrane is made up of lipids,proteins and carbohydrates. Vital Flow Save Your Prostate Get Instant Access An increase in temperature will increase the rate of non-enzyme-catalyzed reactions. A similar relationship between temperature and reaction rate occurs in enzyme-catalyzed reactions. At a temperature of 0° C the reaction rate is immeasurably slow. As the temperature is raised above 0° C the reaction rate increases, but only up to a point. At a few degrees above body temperature (which is 37° C) the reaction rate reaches a plateau; further increases in temperature actually decrease the rate of the reaction (fig. 4.3). This decrease is due to the fact that the tertiary structure of enzymes becomes altered at higher temperatures. A similar relationship is observed when the rate of an enzymatic reaction is measured at different pH values. Each enzyme characteristically exhibits peak activity in a very narrow pH range, which is the pH optimum for the enzyme. If the pH is changed so that it is no longer within the enzyme’s optimum range, the reaction rate will decrease (fig. 4.4). This decreased enzyme activity is due to changes in the conformation of the enzyme and in the charges of the R groups of the amino acids lining the active sites. The pH optimum of an enzyme usually reflects the pH of the body fluid in which the enzyme is found. The acidic pH optimum of the protein-digesting enzyme pepsin, for example, allows it to be active in the strong hydrochloric acid of gastric juice. Similarly, the neutral pH optimum of salivary amylase and the alkaline pH optimum of trypsin in pancreatic juice allow these enzymes to digest starch and protein, respectively, in other parts of the digestive tract. Although the pH of other body fluids shows less variation than that of the fluids of the digestive tract, the pH optima of different enzymes found throughout the body do show significant differences (table 4.3). Some of these differences can be exploited for diagnostic purposes. Disease of the prostate, for example, may be associated with elevated blood levels of a prostatic phosphatase with an acidic pH optimum (descriptively called acid phosphatase). Bone disease, on the other hand, may be associated with elevated blood levels of alkaline phosphatase, which has a higher pH optimum than the similar enzyme released from the diseased prostate. 10 20 30 37 40 100 Temperature (°C) ■ Figure 4.3 The effect of temperature on enzyme activity. This effect is measured by the rate of the enzyme-catalyzed reaction under standardized conditions as the temperature of the reaction is varied. ■ Figure 4.4 The effect of pH on the activity of three digestive enzymes. Salivary amylase is found in saliva, which has a pH close to neutral; pepsin is found in acidic gastric juice, and trypsin is found in alkaline pancreatic juice. Metabolism is a biochemical reaction which occurs in the presence of enzymes. Metabolism plays a vital role in physiology like the digestion of food, absorption, distribution and also excretion. Even waste material and harmful substances like drugs are also metabolized in the body to expel them out through excretory organs. Metabolism is mainly of two types as anabolism and catabolism. In the process of anabolism smaller molecules are aligned to form larger molecules whereas, in catabolism, larger molecules are broken down into smaller ones. Anabolism is mostly necessary for body growth, maintenance (survival) and also for reserve food materials to cope up starvation. Catabolism is essential for wound healing, repair, apoptosis pathway, excretion and also expulsion of toxic waste from the body. Metabolism occurs in the cells, tissues and organs like liver, kidney, lungs, skin, etc. Of them, the lung is the major metabolic organ. What Role do Enzymes Play in Metabolism 1. Help in the formation of macromolecules 2. Help in the conversion of a molecule from one form to another form 3. Aid in the breakdown of large molecules to smaller ones 4. Convert lipophilic molecules to hydrophilic ones 5. Minimize the toxicity of substances. 1. Formation of macromolecules: Enzymes help in the creation of macro-molecules as required by the body. These macromolecules are used for regular physiology or storage. Examples include: a) Conversion of glucose to glycogen by the enzyme glycogen synthase. This glycogen is stored in the liver for future use. b) Conversion of amino acids to peptides by peptide bond formation due to the enzyme peptide synthetases. c) Formation of DNA and RNA by polymerases. 2. Change in the form of molecules: Molecules with the same number of elements in the structure can have different shapes and properties. In one form they can be active while in another form inactive. BY: OpenStax College Wikimedia Commons In the image above, you can notice Oxaloacetic acid converts Malic acid. Both are similar in terms of chemistry. Thus, these molecules are inter-converted based on the requirement by the enzymes like isomerases. 3. Breakdown of large to small molecules: Enzymes are also involved in the breakdown of large molecules to small molecules to meet the needs of the body and also for excretion from the body. Examples: a) Starch is broken down to release glucose in the gut in the presence of digestive enzyme amylase. Credit: oli.cmu.edu b) Glycogen is broken down into glucose by the enzyme glycogen phosphorylase 4. Enhancing the solubility or Convert lipophilic molecules to hydrophilic ones: When a substance is lipophilic, it tends to be distributed in the tissues and cells. When it is hydrophilic, it tries to stay in the water compartment of the body, i.e., blood and other fluids. When a substance is hydrophilic, it can be easily expelled in urine. Credit: auburn.edu Hence, lipophilic substances are converted to hydrophilic ones by enzyme action. One common example of such reaction is glucuronidation. 5. Minimizing the toxicity of substances: When a substance is toxic to the body due to its chemical nature, it is metabolized by enzymes to no toxic one. Here, uridine 5′-diphosphoglucuronic acid is allowed to react with drugs and substance containing functional groups like OH-, NH2- and COOH- etc.