what happens to nutrient macromolecules in an animals digestive tract

THE DIGESTIVE SYSTEM

Digestive System | Plans and Locations | Stages in the Digestive Process

Components of the Digestive System | Regulation of Appetite | Nutrition | Learning Objectives | Links

Animals, for the well-nigh part, ingest their food as large, complex molecules that must be broken down into smaller molecules (monomers) that can so be distributed throughout the body of every cell. This vital function is accpomplished by a series of specialized organs that comprise the digestive organisation. Representative digestive systems are shown in Figure ane.

Digestive System | Back to Meridian

Single-celled organisms can directly take in nutrients from their exterior surround. Multicellular animals, with nigh of their cells removed from contact straight with the outside environment, have developed specialized structures for obtaining and breaking downwardly their nutrient. Animals depend on two processes: feeding and digestion.

Animals are heterotrophs , they must absorb nutrients or ingest food sources. Ingestive eaters , the majority of animals, use a mouth to ingest food. Absorptive feeders , such as tapeworms, live in a digestive system of some other animal and absorb nutrients from that animal straight through their body wall. Filter feeders , such every bit oysters and mussels, collect small organisms and particles from the surrounding water. Substrate feeders , such every bit earthworms and termites, swallow the fabric (dirt or woods) they couch through. Fluid feeders , such as aphids, pierce the body of a constitute or animal and withdraw fluids.

Effigy 1. The digestive systems of representative animals. Images from Purves et al., Life: The Science of Biology, 4th Edition, past Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

Plans and Locations | Back to Top

The digestive system uses mechanical and chemic methods to break food downwards into nutrient molecules that tin can be absorbed into the blood. One time in the blood, the food molecules are routed to every jail cell in the animal's body.

At that place are two types of creature torso plans as well as two locations fordigestion to occur. Sac-like plans are establish in many invertebrates, who take a single opening for nutrient intake and the discharge of wastes. Vertebrates, the fauna grouping humans belong to, utilise the more efficient tube-within-a-tube program with nutrient entering through 1 opening (the mouth) and wastes leaving through another (the anus).

Where the digestion of the food happens is also variable. Some animals use intracellular digestion , where food is taken into cells by phagocytosis with digestive enzymes being secreted into the phagocytic vesicles . This blazon of digestion occurs in sponges, coelenterates (corals, hydras and their relatives) and most protozoans. Extracellular digestion occurs in the lumen (or opening) of a digestive system, with the food molecules beingness transferred to the blood or some other body fluid. This more avant-garde type of digestion occurs in chordates, annelids, and crustaceans.

Stages in the Digestive Process | Back to Meridian

Nutrient for the most function consists of various organic macromolecules such every bit starch, proteins, and fats. These molecules are polymers made of private monomer units (as discussed in an earlier affiliate). Breaking these large molecules into smaller components involves:

movement: propels food through the digestive organization
secretion : release of digestive juices in response to a specific stimulus
digestion : breakdown of food into molecular components small-scale enough to cross the plasma membrane
assimilation : passage of the molecules into the body's interior and their passage throughout the trunk
emptying: removal of undigested nutrient and wastes

3 processes occur during what we loosely refer to equally "digestion". Digestion proper, which is the mechanical and chemical breakdown of food into particles/molecules small enough to pass into the claret. Assimilation is the passage of food monomers into the blood stream. Absorption is the passage of the food molecules into body cells.

Components of the Digestive Organisation | Back to Top

The human digestive arrangement, as shown in Figure two, is a coiled, muscular tube (half-dozen-nine meters long when fully extended) stretching from the mouth to the anus. Several specialized compartments occur along this length: oral fissure, pharynx, esophagus, stomach, small intestine, large intestine, and anus. Accessory digestive organs are continued to the master organization by a series of ducts: salivary glands, parts of the pancreas, and the liver and gall bladder ( bilary arrangement ).

Effigy 2. The human digestive system. Images from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates ( world wide web.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

The Mouth and Throat

Mechanical breakdown begins in the mouth by chewing (teeth) and actions of the natural language. Chemic breakdown of starch past production of salivary amylase from the salivary glands . This mixture of food and saliva is then pushed into the pharynx and esophagus . The esophagus is a muscular tube whose muscular contractions ( peristalsis ) propel food to the tummy.

In the rima oris, teeth, jaws and the natural language begin the mechanical breakdown of food into smaller particles, equally shown in Effigy 3. Nearly vertebrates, except birds (who have lost their teeth to a hardened beak), have teeth for tearing, grinding and chewing food. The tongue manipulates food during chewing and swallowing; mammals accept tastebuds clustered on their tongues.

Salivary glands secrete salivary amylase, an enzyme that begins the breakup of starch into glucose. Mucus moistens food and lubricates the esophagus. Bicarbonate ions in saliva neutralize the acids in foods.

Swallowing moves food from the mouth through the throat into the esophagus and and then to the stomach.

Step one: A mass of chewed, moistened food, a bolus, is moved to the back of the moth by the tongue. In the pharynx, the bolus triggers an involuntary swallowing reflex that prevents food from entering the lungs, and directs the bolus into the esophagus.
Pace 2: Muscles in the esophagus propel the bolus past waves of involuntary muscular contractions (peristalsis) of polish muscle lining the esophagus. Peristalsis is shown in Figure iv.
Step 3: The bolus passes through the gastroesophogeal sphincter, into the stomach. Heartburn results from irritation of the esophagus by gastric juices that leak through this sphincter.

Figure 3. Structure of the throat and the mechanics of swallowing. Image from Purves et al., Life: The Science of Biological science, 4th Edition, by Sinauer Associates ( world wide web.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

Figure 4. Peristalsis and the movement of food from the mouth to the stomach. Image from Purves et al., Life: The Science of Biology, 4th Edition, past Sinauer Associates ( www.sinauer.com ) and WH Freeman ( world wide web.whfreeman.com ), used with permission.

The Breadbasket (or Churn, Churn, Churn)

During a meal, the breadbasket gradually fills to a capacity of 1 liter, from an empty capacity of l-100 milliliters. At a toll of discomfort, the stomach tin can distend to concur ii liters or more than.

Epithelial cells line inner surface of the breadbasket, as shown in Figure 5, and secrete about 2 liters of gastric juices per twenty-four hour period. Gastric juice contains hydrochloric acid, pepsinogen , and mucus; ingredients of import in digestion. Secretions are controlled past nervous (smells, thoughts, and caffeine) and endocrine signals. The breadbasket secretes hydrochloric acid and pepsin . Muriatic acid (HCl) lowers pH of the stomach then pepsin is activated. Pepsin is an enzyme that controls the hydrolysis of proteins into peptides. The tum also mechanically churns the food. Chyme, the mix of acrid and food in the stomach, leaves the tum and enters the small intestine.

Hydrochloric acrid does not directly function in digestion: it kills microorganisms, lowers the stomach pH to between 1.v and two.5; and activates pepsinogen. Pepsinogen is an enzyme that starts protein digestion. Pepsinogen is produced in cells that line the gastric pits . It is activated by cleaving off a portion of the molecule, producing the enzyme pepsin that splits off fragments of peptides from a protein molecule during digestion in the stomach.

Carbohydrate digestion, begun by salivary amylase in the rima oris, continues in the bolus every bit it passes to the tummy. The bolus is broken down into acid chyme in the lower tertiary of the stomach, assuasive the stomach's acerbity to inhibit further carbohydrate breakdown. Protein digestion by pepsin begins.

Alcohol and aspirin are absorbed through the stomach lining into the claret.

Epithelial cells secrete mucus that forms a protective barrier between the cells and the stomach acids. Pepsin is inactivated when it comes into contact with the mucus. Bicarbonate ions reduce acidity near the cells lining the tum. Tight junctions link the epithelial stomach-lining cells together, farther reducing or preventing tum acids from passing.

Ulcers

Peptic ulcers result when these protective mechanisms fail. Bleeding ulcers result when tissue damage is so severe that bleeding occurs into the stomach. Perforated ulcers are life-threatening situations where a hole has formed in the stomach wall. At to the lowest degree 90% of all peptic ulcers are acquired by Helicobacter pylori. Other factors, including stress and aspirin, can also produce ulcers.

The Small Intestine

The small intestine , shown in Figure half dozen, is where final digestion and assimilation occur. The small intestine is a coiled tube over 3 meters long. Coils and folding plus villi give this 3m tube the surface expanse of a 500-600m long tube. Last digestion of proteins and carbohydrates must occur, and fats have not withal been digested. Villi have cells that produce intestinal enzymes which consummate the digestion of peptides and sugars. The absorption process likewise occurs in the small intestine. Nutrient has been broken down into particles minor enough to pass into the modest intestine. Sugars and amino acids go into the bloodstream via capillaries in each villus. Glycerol and fatty acids become into the lymphatic system. Assimilation is an active ship, requiring cellular energy.

Figure 6. Structure and details of the pocket-sized intestine. Images from Purves et al., Life: The Scientific discipline of Biology, fourth Edition, by Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

Food is mixed in the lower function of the tummy by peristaltic waves that also propel the acrid-chyme mixture against the pyloric sphincter. Increased contractions of the stomach button the food through the sphincter and into the small intestine as the stomach eempties over a i to ii 60 minutes period. High fat diets significantly increase this time period.

The pocket-sized intestine is the major site for digestion and absorption of nutrients. The small intestine is upwards to 6 meters long and is 2-three centimeters wide. The upper part, the duodenum , is the well-nigh active in digestion. Secretions from the liver and pancreas are used for digestion in the duodenum. Epithelial cells of the duodenum secrete a watery mucus. The pancreas secretes digestive enzymes and stomach acrid-neutralizing bicarbonate. The liver produces bile, which is stored in the gall bladder before entering the bile duct into the duodenum.

Digestion of carbohydrates, proteins, and fats continues in the minor intestine. Starch and glycogen are broken down into maltose past small intestine enzymes. Proteases are enzymes secreted past the pancreas that continue the breakdown of protein into small peptide fragments and amino acids.

Bile emulsifies fats, facilitating their breakup into progressively smaller fat globules until they can be acted upon past lipases . Bile contains cholesterol, phospholipids, bilirubin, and a mix of salts. Fats are completely digested in the pocket-size intestine, dissimilar carbohydrates and proteins.

About assimilation occurs in the duodenum and jejeunum (second third of the small intestine). The inner surface of the intestine has circular folds that more than triple the surface surface area for absorption. Villi covered with epithelial cells increase the surface area by some other factor of 10. The epithelial cells are lined with microvilli that further increase the surface surface area; a vi meter long tube has a surface expanse of 300 square meters.

Each villus has a surface that is adjacent to the inside of the modest intestinal opening covered in microvilli that class on elevation of an epithelial prison cell known as a brush edge . Each villus has a capillary network supplied by a minor arteriole. Captivated substances pass through the castor border into the capillary, usually by passive transport.

Maltose, sucrose, and lactose are the main carbohydrates present in the modest intestine; they are absorbed past the microvilli. Starch is broken down into ii-glucose units (maltose) elsewhere. Enzymes in the cells convert these disaccharides into monosaccharides that then leave the prison cell and enter the capillary. Lactose intolerance results from the genetic lack of the enzyme lactase produced by the intestinal cells.

Peptide fragments and amino acids cross the epithelial cell membranes by active send . Inside the cell they are cleaved into amino acids that then enter the capillary. Gluten enteropathy is the inability to absorb gluten, a protein establish in wheat.

Digested fats are not very soluble. Bile salts surroundings fats to form micelles , as shown in Figure vii, that can pass into the epithelial cells. The bile salts return to the lumen to repeat the procedure. Fat digestion is normally completed past the fourth dimension the food reaches the ileum (lower third) of the small-scale intestine. Bile salts are in turn captivated in the ileum and are recycled past the liver and gall bladder. Fats pass from the epithelial cells to the small lymph vessel that also runs through the villus.

Figure vii. Absorption of lipids by cells in the small intestine. Images from Purves et al., Life: The Science of Biology, quaternary Edition, past Sinauer Associates ( world wide web.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

The Liver and Gall Bladder

The liver produces and sends bile to the minor intestine via the hepatic duct, as illustrated in Effigy 8. Bile contains bile salts, which emulsify fats, making them susceptible to enzymatic breakdown. In improver to digestive functions, the liver plays several other roles: 1) detoxification of claret; 2) synthesis of blood proteins; three) destruction of old erythrocytes and conversion of hemoglobin into a component of bile; 4) production of bile; 5) storage of glucose as glycogen , and its release when blood sugar levels drib; and 6) production of urea from amino groups and ammonia.

Figure eight. The liver and associated organs and their connections to the digestive system. Images from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), used with permission.

The gall float stores excess bile for release at a later time. We can live without our gall bladders, in fact many people accept had theirs removed. The drawback, however, is a need to be aware of the amount of fats in the food they consume since the stored bile of the gall bladder is no longer available.

Glycogen is a polysaccharide made of bondage of glucose molecules, as shown in Figure 9. In plants starch is the storage course of glucose, while animals use glycogen for the aforementioned purpose. Low glucose levels in the blood cause the release of hormones, such every bit glucagon , that travel to the liver and stimulate the breakdown of glycogen into glucose, which is then released into the blood(raising claret glucose levels). When no glucose or glycogen is available, amino acids are converted into glucose in the liver. The process of deamination removes the amino groups from amino acids. Urea is formed and passed through the blood to the kidney for export from the body. Conversely, the hormone insulin promotes the accept-up of glusose into liver cells and its formation into glycogen.

Liver diseases

Jaundice occurs when the feature yellowish tint to the skin is caused past excess hemoglobin breakdown products in the claret, a sign that the liver is non properly functioning. Jaundice may occur when liver part has been impaired past obstruction of the bile duct and by damage caused by hepatitis .

Hepatitis A, B, and C are all viral diseases that can crusade liver damage. Like any viral affliction, the major treatment efforts focus on treatment of symptoms, not removal of the viral cause. Hepatitis A is unremarkably mild malady indicated by a sudden fever, malaise, nausea, anorexia, and abdominal discomfort. Jaundice follows up for several days. The virus causing Hepatitis A is primarilly transmitted by fecal contamination, although contaminated food and water also can promote transmission. A rare disease in the United States, hepatitis B is endemic in parts of Asia where hundreds of millions of individuals are possibly infected.

Hepatitis B may exist transmitted by claret and claret products as well every bit sexual contact. The claret supply in developed countries has been screened for the virus that causes this disease for many years and transmission by claret transfusion is rare. The take chances of HBV infection is high amongst promiscuous homosexual men although it is also transmitted hetereosexually. Correct use of condoms is thought to reduce or eliminate the risk of manual. Effective vaccines are available for the prevention of Hepatitis B infection. Some individuals with chronic hepatitis B may develop cirrhosis of the liver. Individuals with chronic hepatitis B are at an increased risk of developing chief liver cancer. Although this type of cancer is relatively rare in the United states of america, information technology is the leading cause of cancer death in the world, primarily because the virus causing it is endemic in east asia.

Hepatitis C affects approximately 170 million people worldwide and 4 meg in the Usa. The virus is transmitted primarily by blood and blood products. Most infected individuals have either received claret transfusions prior to 1990 (when screening of the blood supply for the Hepatitis C virus began) or take used intravenous drugs. Sexual manual tin can occur between monogamous couples (rare) but infection is far more common in those who are promiscuous. In rare cases, Hepatitis C causes acute illness and even liver failure. About twenty pct of individuals with Hepatitis C who develop cirrhosis of the liver will also develop astringent liver disease. Cirrhosis caused past Hepatitis C is soon the leading cause of the demand for liver transplants in the U.s.. Individuals with cirrhosis from Hepatitis C also bear increased chances of developing master liver cancer. All current treatments for Hepatitis C employ of diverse preparations of the potent antiviral interferon alpha. However, not all patients who have the illness are good candidates for treatment, then infected individuals are urged to regularly consult their doc.

Cirrhosis of the liver commonly occurs in alcoholics, who place the liver in a stress state of affairs due to the amount of booze to be cleaved down. Cirrhosis tin cause the liver to become unable to perform its biochemical functions. Chemicals responsible for blood clotting are synthesized in the liver, as is albumin, the major protein in blood. The liver also makes or modifies bile components. Blood from the circulatory organisation passes through the liver, so many of the body'southward metabolic functions occur primarily there including the metabolism of cholesterol and the conversion of proteins and fats into glucose. Cirrhosis is a disease resulting from damage to liver cells due to toxins, inflammation, and other causes. Liver cells regenerate in an abnormal pattern primarily forming nodules that are surrounded past fibrous tissue. Changes in the structure of the liver can decrease blood menses, leading to secondary complications. Cirrhosis has many cuses, including alcoholic liver disease, severe forms of some viral hepatitis, congestive heart failure, parasitic infections (for instance schistosomiasis), and long term exposure to toxins or drugs.

The Pancreas

The pancreas sends pancreatic juice, which neutralizes the chyme, to the minor intestive through the pancreatic duct. In addition to this digestive function, the pancrease is the site of production of several hormones, such equally glucagon and insulin.

The pancreas contains exocrine cells that secrete digestive enzymes into the small intestine and clusters of endocrine cells (the pancreatic islets ). The islets secrete the hormones insulin and glucagon , which regulate blood glucose levels.

After a meal, blood glucose levels ascent, prompting the release of insulin, which causes cells to take upward glucose, and liver and skeletal musculus cells to class the carbohydrate glycogen . As glucose levels in the blood fall, further insulin product is inhibited. Glucagon causes the breakdown of glycogen into glucose, which in turn is released into the claret to maintain glucose levels within a homeostatic range. Glucagon production is stimulated when blood glucose levels fall, and inhibited when they ascension.

Diabetes results from inadequate levels of insulin. Type I diabetes is characterized past inadequate levels of insulin secretion, often due to a genetic cause. Type 2 ordinarily develops in adults from both genetic and environmental causes. Loss of response of targets to insulin rather than lack of insulin causes this type of diabetes. Diabetes may cause impairment in the functioning of the eyes, circulatory system, nervous organization, and failure of the kidneys. Diabetes is the second leading cause of blindness in the Usa. Treatments might involve daily injections of insulin, oral medications such as metformin, monitoring of blood glucose levels, and a controlled diet. Type I diabetes may i day be cured by advances in factor therapy/stem prison cell inquiry. On recently recognized condition is known as prediabetes, in which the body gradually loses its sensitivity to insulin, leading eventually to Type II diabetes. Ora; medications, diet and behavior (in other words Do!!!) changes are thought to delay if not outright postpone the onset of diabetes if corrected soon plenty.

The fifth leading crusade of cancer decease in the United states of america is from pancreatic cancer, which is nearly always fatal. Scientists estimate that 25,000 people may die from this affliction each twelvemonth. Standard treatments are ineffective, although some promising avenues may open with advances in genomics and molecular biology of cancer cells.

The Large Intestine

The large intestine is fabricated upwards past the colon, cecum, appendix , and rectum. Cloth in the big intestine is mostly indigestible residue and liquid. Movements are due to involuntary contractions that shuffle contents back and along and propulsive contractions that move material through the large intestine. The large intestine performs three bones functions in vertebrates: ane) recovery of h2o and electrolytes from digested nutrient; 2) formation and storage of feces; and 3) microbial fermentation: The large intestine supports an amazing flora of microbes. Those microbes produce enzymes that can digest many of molecules indigestible by vertebrates.

Secretions in the big intestine are an alkali metal fungus that protects epithelial tissues and neutralizes acids produced by bacterial metabolism. H2o, salts, and vitamins are captivated, the remaining contents in the lumen form feces (mostly cellulose, bacteria, bilirubin). Bacteria in the large intestine, such as E. coli, produce vitamins (including vitamin K) that are absorbed.

Regulation of Appetite | Back to Peak

The hypothalamus in the encephalon has two centers decision-making hunger. One is the appetite centre, the other the satiety middle.

Gastrin , secretin , and cholecystokinin are hormones that regulate various stages of digestion. The presence of protein in the tummy stimulates secretion of gastrin, which in turn volition cause increased stomach acid secretion and mobility of the digestive tract to move food. Food passing into the duodenum causes the production of secretin, which in plough promotes release of alkaline secretions from the pancreas, stops further passage of nutrient into the intestine until the acid is neutralized. Cholecystokinin (CCK) is released from intestinal epithelium in response to fats, and causes the release of bile from the gall bladder and lipase (a fat digesting enzyme) from the pancreas.

Nutrition | Dorsum to Top

Diet deals with the composition of food, its energy content, and slowly (or not at all) synthesized organic molecules. Chemotrophs are organisms (mostly bacteria) deriving their energy from inorganic chemical reactions. Phototrophs convert sunlight free energy into sugar or other organic molecules. Heterotrophs eat to obtain energy from the breakdown of organic molecules in their food.

Macronutrients are foods required on a large scale each solar day. These include carbohydrates, lipids, and amino acids. Water is essential, correct water residuum is a must for proper functioning of the body.

Nigh threescore% of the diet should exist carbohydrates, obtained from foods such every bit milk, meat, vegetables, grains and grain products. The diet should incorporate at least 100 grams of carbohydrate every day. Recently, still, new recommendations have been developed that suggest a lowering of the amount of carbohydrate. A more detailed presentation of this topic may be fount at http://wellness.discovery.com/diseasesandcond/encyclopedia/2935.html .

Proteins are polymers composed of amino acids. Proteins are found in meat, milk, poultry, fish, cereal grains and beans. They are needed for cellular growth and repair. Twenty amino acids are constitute in proteins, of which humans can make eleven. The remaining 9 are the essential amino acids which must be supplied in the diet. Ordinarily proteins are not used for energy, nevertheless during starvation (or a depression-carb diet) musculus proteins are broken downward for energy. Excess protein can be used for energy or converted to fats.

Lipids and fats generate the greatest energy yield, so a large number of plants and animals store excess nutrient energy equally fats. Lipids and fats are present in oils, meats, butter, and plants (such as avocado and peanuts). Some fatty acids, such as linoleic acid, are essential and must be included in the nutrition. When present in the intestine, lipids promote the uptake of vitamins A, D, Eastward, and K.

Vitamins are organic molecules required for metabolic reactions. They usually cannot be fabricated by the body and are needed in trace amounts. Vitamins may act as enzyme cofactors or coenzymes . Some vitamins are soluble in fats, some in h2o.

Minerals are trace elements required for normal metabolism, as components of cells and tissues, and for nerve conduction and muscle contraction. They can simply exist obtained from the diet. Iron (for hemoglobin), iodine (for thyroxin), calcium (for bones), and sodium (nervus message transmission) are examples of minerals.

There is a quantitative human relationship betwixt nutrients and wellness. Imbalances can cause disease. Many studies accept concluded diet is a major cistron in cardiovascular disease, hypertension, and cancer.

Learning Objectives | Dorsum to Top

Listing all parts (in order) of the human digestive arrangement through which food actually passes. And then listing the auxiliary organs that contribute one or more substances to the digestive procedure.
Explain how, during digestion, food is mechanically broken downward. And then explain how information technology is chemically cleaved downwards.
Describe how the digestion and assimilation of fats differ from the digestion and absorption of carbohydrates and proteins.
Describe the cross-exclusive structure of the small intestine and explain how its structure is related to its function.
List iv functions of the liver.

Terms | Back to Acme

absorption	absorbent feeders	absorption	bilary system	brush border	chyme
cirrhosis	diabetes	digestion	digestive system	disaccharides	duodenum
epithelial cells	erythrocytes	esophagus	extracellular digestion	filter feeders	fluid feeders
gastric pits	glucagon	glycogen	hemoglobin	hepatitis	heterotrophs
ileum	ingestive eaters	insulin	intracellular digestion	jejeunum	lactose intolerance
large intestine	lipases	macronutrients	micelles	microvilli	minerals
monosaccharides	fungus	pancreas	pancreatic islets	pepsin	pepsinogen
peptic ulcers	peristalsis	phagocytosis	pharynx	phototrophs	salivary amylase
salivary glands	secretion	minor intestine	substrate feeders	tube-inside-a-tube plan	vesicles
villi	vitamins

Review Questions | Back to Top

Under Construction

Links | Back to Top

Your Digestive System and How it Works National Constitute of Health provides a summary.
The Digestive System Page This folio takes a very long time to download a big number of impressive photographs of the system. Kristie Allen, Montana State University.
Net Doctor In that location are several systems covered from this site, including an blitheness of the digestive organization.
The Human Digestive Organisation Nancy Haupt, University of W Florida.
Introductory Beefcake: The Human Digestive System Lecture notes from Dr. D. R. Johnson, Academy of Leeds.
Helicobacter pylori This folio will explain the ulcers I requite you lot ;)
Lactose Intolerance Text with a few graphics about a sensitive trouble to many people.
Diseases of the Liver From this page you lot tin access a bully deeal of hyperlinkes and other information about diseases that affect the liver. Folio by Howard J. Worman, M. D of Columbia University.
The American Liver Foundation The page is the official website of the American Liver Foundation, and makes a expert starting point to explore further on liver conditions and associated facts.
The National Pancreas Foundation Similar to the Liver Foundation link to a higher place, this site offers details on pancreas illnesses and functions.
The American Diabetes Association Learn well-nigh the silent affliction that is reaching epidemic porportions in the Us. Diabetes is a leading killer, observe out what this organization is doing to thwart it, likewise equally facts most an all likewise common malady.
Discovery Heath Nutrition This folio from discovery.com offers a oft updated set of links as well as new manufactures covering aspects of diet, including links to diseases of the digestive system.

Dorsum to Table of Contents | THE NERVOUS System

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