Gastrointestinal (GI) Motility
A small, pear-shaped pouch beneath the liver, the gallbladder plays an essential role in maintaining a smooth and healthy digestion. Each part of the gastrointestinal tract has a unique function to perform in digestion, Is a reflex that is initiated when a bolus of food stimulates tactile receptors in the contraction of the gallbladder for bile release; regulated gastric emptying to. The human digestive system consists of the gastrointestinal tract plus the accessory organs of The organs known as the accessory digestive glands are the liver, gall bladder . The function of taste perception is vital to help prevent harmful or rotten foods from .. JAMA: The Journal of the American Medical Association.
Its anatomical position in the body is immediately under the diaphragm on the right side of the upper abdomen, The liver lies on the right side of the stomach and makes a kind of bed for the gallbladder. The liver is supplied by two main blood vessels on its right lobe: The hepatic artery normally comes off the celiac trunk. The portal vein brings venous blood from the spleen, pancreas, and small intestine, so that the liver can process the nutrients and byproducts of food digestion.
The hepatic veins drain directly into the inferior vena cava. The bile produced in the liver is collected in bile canaliculi, which merge from bile ducts. These eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct. The cystic duct from the gallbladder joins with the common hepatic duct to form the common bile duct. Bile can either drain directly into the duodenum via the common bile duct or be temporarily stored in the gallbladder via the cystic duct.
The common bile duct and the pancreatic duct enter the duodenum together at the ampulla of Vater. The branching's of the bile ducts resemble those of a tree, and indeed term "biliary tree" is commonly used in this setting. The liver is among the few internal human organs capable of natural regeneration of lost tissue: This is predominantly due to hepatocytes acting as unipotential stem cells.
There is also some evidence of bio potential stem cells, called oval cell, which can differentiate into either hepatocytes or cholangiocytes cells that line bile ducts. The various functions of the liver are carried out by the liver cells or hepatocytes. The liver produces and excretes bile, required for dissolving fats.
Some of the bile drains directly into the duodenum, and some is stored in the gallbladder The liver performs several roles in carbohydrate metabolism: The liver also performs several roles in lipid metabolism: The liver breaks down hemoglobin, creating metabolites that are added to bile as pigment The liver breaks down toxic substances and most medicinal products in a process called drug metabolism.
This sometimes results in toxication, when the metabolite is more toxic than its precursor. The liver converts ammonia to urea. The liver stores a multitude of substances, including glucose in the form of glycogen, vitamin B12, iron, and copper. In the first trimester fetus, the liver is the main site of red blood cell production. By the 32nd weeks of gestation, the bone marrow has almost completely taken over that task. The liver is responsible for immunological effects; the reticuloendothelial system of the liver contains many immunologically active cells, acting as a 'sieve' for antigens carried to it via the portal system.
Gallbladder The gallbladder is a pear shaped organ that stores about 50 ml of bile or "gall" until the body needs it for digestion. The gallbladder is about cm long in humans and is dark green in appearance due to its contents bilenot its tissue. It is connected to the liver and the duodenum by the biliary tract. The gallbladder is connected to the main bile duct through the gallbladder duct cystic duct.
The main biliary tract runs from the liver to the duodenum, and the cystic duct is effectively a "cul de sac", serving as entrance and exit to the gallbladder. The surface marking of the gallbladder is the intersection of the midclavicular line MCL and the trans pyloric plane, at the tip of the ninth rib.
The blood supply is by the cystic artery and vein, which runs parallel to the cystic duct. The cystic artery is highly variable, and this is of clinical relevance since it must be clipped and cut during a cholecystectomy. The gallbladder has an epithelial lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining.
Under the epithelium there is a layer of connective tissue, followed by a muscular wall that contracts in response to cholecystokinin, a peptide hormone synthesized in the duodenum. The gallbladder stores bile, which is released when food containing fat enters the digestive tract, stimulating the secretion of cholecystokinin CCK.
The bile emulsifies fats and neutralizes acids in partly digested food. After being stored in the gallbladder, the bile becomes more concentrated than when it left the liver, increasing its potency and intensifying its effect on fats. Anus[ edit ] The human anus is situated between the buttocks, posterior to the perineum. It has two anal sphincters, one internal, the other external.
These hold the anus closed until defecation occurs. One sphincter consists of smooth muscle and its action is involuntary; the other consists of striated muscle and its action is voluntary.
In many animals, the anus is surrounded by anal sacs. Role of the anus is when the rectum is full, the increase in intra-rectal pressure forces the walls of the anal canal apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic waves propel the feces out of the rectum.
The internal and external sphincters of the anus allow the feces to be passed by muscles pulling the anus up over the exiting feces. Conditions Affecting the Esophagus[ edit ] There are two different types of conditions that may affect the esophagus.
the digestive system
The first type is called congenital: The second type is called non-congenital: Some examples of these are: Tracheoesophageal fistula and esophageal atresia Both of these conditions are congenital. In Tracheoesophageal fistula there is a connection between the esophagus and the wind pipe trachea where there shouldn't be one.
In Esophageal atresia the esophagus of a newborn does not connect to the stomach but comes to a dead end right before the stomach. Both conditions require corrective surgery and are usually detected right after the baby is born. In some cases, it can be detected before the baby is born. Esophagitis Esophagitis is inflammation of the esophagus and is a non-congenital condition.
Esophagitis can be caused by certain medications or by infections. It can also be caused by gastroesophageal reflux disease gerda condition where the esophageal sphincter allows the acidic contents of the stomach to move back up into the esophagus. Gastroesophageal reflux disease can be treated with medications, but it can also be corrected by changing what you eat. Conditions Affecting the Stomach and Intestines[ edit ] Everybody has experienced constipation or diarrhea in their lifetime.
With constipation, the contents of the large intestines don't move along fast enough and waste material stays in the large intestines so long that almost all water is extracted out of the waste and it becomes hard. With diarrhea you get the exact opposite reaction: Common flora bacteria assists in the prevention of many serious problems. Here are some more examples of common stomach and intestinal disorders: An exemplary case of acute appendicitis in a year-old boy.
The organ is enlarged and sausage-like botuliform. This longitudinal section shows the angry red inflamed mucosa with its irregular luminal surface.
Diagnosed and removed early in the course of the disease, this appendix does not show late complications, like transmural necrosis, perforation, and abscess formation.
Appendicitis Appendicitis is the inflammation of the appendix, the finger-like pouch that extends from the cecum. The most common symptoms are abdominal pain, loss of appetite, fever, and vomiting. Children and teenagers are the most common victims of appendicitis, which must be corrected by surgery. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy.
Untreated, mortality is high, mainly due to peritonitis and shock. Celiac Disease Celiac disease is a disorder in which a person's digestive system is damaged by the response of the immune system to a protein called gluten, which is found in rye, wheat, and barley, and also in foods like breakfast cereal and pizza crust. People who have celiac disease experience abdominal pain, diarrhea, bloating, exhaustion, and depression when they eat foods with gluten in them.
They also have difficulty digesting their food. Celiac disease runs in families and becomes active after some sort of stress, like viral infections or surgery. The symptoms can be managed by following a gluten free diet. Doctors can diagnose this condition by taking a full medical history or with a blood test. Diverticulitis Benign gastric ulcer Diverticulitis is a common disease of the bowel, in particular the large intestine.
Diverticulitis develops from diverticulosis, which involves the formation of pouches diverticula on the outside of the colon. Diverticulitis results if one of these diverticula becomes inflamed. In complicated diverticulitis, bacteria may subsequently infect the outside of the colon if an inflamed diverticula bursts open.
If the infection spreads to the lining of the abdominal cavity peritoneumthis can cause a potentially fatal peritonitis. Sometimes inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. Also, the affected part of the colon could adhere to the bladder or other organ in the pelvic cavity, causing a fistula, or abnormal communication between the colon and an adjacent organ.
Gastritis and Peptic ulcers Usually the stomach and the duodenum are resistant to irritation because of the strong acids produced by the stomach. But sometimes a bacteria called Helicobacter pylori or the chronic use of drugs or certain medications, weakens the mucous layer that coats the stomach and the duodenum, allowing acid to get through the sensitive lining beneath.
This can cause irritation and inflammation of the lining of the stomach, which is called gastritis, or cause peptic ulcers, which are holes or sores that form in the lining of the stomach and duodenum and cause pain and bleeding. Medications are the best way to treat this condition. Gastrointestinal Infections Gastrointestinal infections can be caused by bacteria such as Campylobacter, Salmonella, E.
They can also be caused by viruses or by intestinal parasites like amebiasis and Giardiasis. The most common symptoms of gastrointestinal infections are abdominal pain and cramps, diarrhea, and vomiting. These conditions usually go away on their own and don't need medical attention. Inflammatory Bowel Disease Inflammatory bowel disease is the chronic inflammation of the intestines, which usually affects older children, teens and adults. Ulcerative colitis usually affects just the rectum and large intestine, while Crohn's disease can affect the whole gastrointestinal tract from mouth to anus along with some other parts of the body.
Patients with these diseases also suffer from extraintestinal symptoms including joint pain and red eye, which can signal a flare of the disease. These diseases are treated with medications and if necessary, Intravenous or IV feeding, or in the more serious cases, surgery to remove the damaged areas of the intestines.
Polyp A polyp is an abnormal growth of tissue tumor projecting from a mucous membrane. If it is attached to the surface by a narrow elongated stalk it is said to be pedunculated. If no stalk is present it is said to be sessile. Polyps are commonly found in the colon, stomach, nose, urinary bladder and uterus.
They may also occur elsewhere in the body where mucous membranes exist like the cervix and small intestine. Disorders of the Pancreas, Liver, and Gallbladder[ edit ] Disorders of the pancreas, liver, and gallbladder affect the ability to produce enzymes and acids that aid in digestion.
Cystic Fibrosis Cystic fibrosis is a chronic, inherited illness where the production of abnormally thick mucous blocks the duct or passageways in the pancreas and prevents the digestive fluids from entering the intestines, making it difficult for the person with the disorder to digest protein and fats, which cause important nutrients to pass through without being digested.
People with this disorder take supplements and digestive enzymes to help manage their digestive problems. Hepatitis Hepatitis is a viral condition that inflames a person's liver which can cause it to lose its ability to function. Viral hepatitis, like hepatitis A, B, and C, is extremely contagious. Hepatitis A, which is a mild form of hepatitis, can be treated at home, but more serious cases that involve liver damage, might require hospitalization. Cholecystitis Acute or chronic inflammation if the gallbladder causes abdominal pain.
The actual inflammation is due to secondary infection with bacteria of an obstructed gallbladder, with the obstruction caused by the gallstones. Gallbladder conditions are very rare in kids and teenagers but can occur when the kid or teenager has sickle cell anemia or in kids being treated with long term medications.
Cholestasis Cholestasis is the blockage in the supply of bile into the digestive tract. It can be "intrahepatic" the obstruction is in the liver or "extrahepatic" outside the liver. It can lead to jaundice, and is identified by the presence of elevated bilirubin level that is mainly conjugated. Biliary colic This is when a gallstone blocks either the common bile duct or the duct leading into it from the gallbladder. This condition causes severe pain in the right upper abdomen and sometimes through to the upper back.
It is described by many doctors as the most severe pain in existence, between childbirth and a heart attack. Other symptoms are nausea, vomiting, diarrhea, bleeding caused by continual vomiting, and dehydration caused by the nausea and diarrhea. Another more serious complication is total blockage of the bile duct which leads to jaundice, which if it is not corrected naturally or by surgical procedure can be fatal, as it causes liver damage.
The only long term solution is the removal of the gallbladder. Gastrointestinal Dysfunctions[ edit ] As we age, the amount of digestive enzymes produced by the body drops way down. This leads to decreased and slower digestion, slower absorption of nutrients and increased accumulation of fecal mater in the intestinal tract.
Undigested food material and metabolic waste can also build up due to slow elimination, starting a series of health problems. When digestion slows, it turns the intestines into a toxic environment.
Helpful organisms cannot live in toxic environments. When the beneficial organisms die they are replaced by harmful organisms, such as yeasts and parasites, the most common being Candida albicans. This leads to changes in the intestinal wall which produce leaky gut syndrome, which allows many toxic chemicals to be introduced into the bloodstream. As a result, the entire toxic load of the body is increased, causing a bigger burden on the liver, kidneys and other body organs.
When this happens the organs that are normally used for eliminating waste and supplying nutrients to the GI tract become a large dump for waste. This problem can be made worse by the use of prescriptions and over-the-counter medications, antibiotics, and a diet that is too low in fiber or contains 'junk food'.
Most people never think about their GI tract. We are concerned about what the outside of our bodies look like, but we completely ignore the inside. Because our bodies a very resilient, deterioration of the digestive system can go on for years with no symptoms or side-effects.
When symptoms finally do appear they are usually very non-specific, and include: Over the years these symptoms become more serious, including: Poor digestion, poor absorption, and bacterial imbalance can be traced to many chronic conditions.
Every organ in the body receives nutrients from the GI tract; if the GI tract is malfunctioning then the whole body suffers. It is possible to return good health to your GI tract by improving digestion, consuming the right amount of fiber, and cutting out junk food and refined sugars. You can improve the function of the intestines by taking fiber supplements and vitamins especially B12 and vitamin K.
Some doctors suggest herbal or vitamin enemas to cleanse and relieve constipation and to help stimulate peristaltic movement which will help to move the bowels.
Irritable Bowel Syndrome Irritable Bowel Syndrome IBS is a disorder with symptoms that are most commonly bloating, abdominal pain, cramping, constipation, and diarrhea. IBS causes a lot of pain and discomfort. It does not cause permanent damage to the intestines and does not lead to serious diseases such as cancer. Most of the people affected with IBS can control their symptoms with stress management, diet, and prescription medication. For others IBS can be debilitating, they may be unable to go to work, travel, attend social events or leave home for even short periods of time.
About 20 percent of the adult population has some symptoms of IBS, making it one of the most common intestinal disorders diagnosed by physicians. It is more common in men than women and in about 50 percent of people affected it starts at about age Researchers have not found out what exactly causes IBS. One idea is that people with IBS have a large intestine colon that is sensitive to certain foods and stress.How your digestive system works - Emma Bryce
The immune system may also be involved. It has also been reported that serotonin is linked with normal GI functioning. People with IBS have diminished receptor activity, causing abnormal levels of serotonin in the GI tract.
Because of this, IBS patients experience problems with bowel movement, motility, and the sensation having more sensitive pain receptors in their GI tract.
Many IBS patients suffer from depression and anxiety which can make symptoms worse. There is no cure for IBS, but medications are an important part of relieving symptoms.
Human Physiology/The gastrointestinal system - Wikibooks, open books for an open world
Fiber supplements or laxatives are helpful for constipation. Anti diarrhoeals such as Imodium can help with diarrhea. An antispasmodic is commonly prescribed for colon muscle spasms. Antidepressants and pain medication are also commonly prescribed. These types of cancers begin in the connective tissue like fat, muscles, nerves, cartilage, etc. GIST originates in the stroma cells.
Stroma cells are strung along the GI tract and are part of the system that helps the body to know when to move food through the digestive system. Over half of GISTs occur in the stomach. Most cases occur in people between the ages of forty and eighty, but they can also occur in a person of any age. All GISTs of any size or location have the ability to spread. In the early stages, GIST is hard to diagnose because early-stage symptoms cannot be recognized. In the later stages a person can have vague abdominal pain, vomiting, abdominal bleeding that shows up in stool or vomit, low blood counts causing anemia, and having an early feeling of being full, causing a decrease in appetite.
GIST is now recognized as an aggressive cancer that is able to spread to other parts of the body. People who have been diagnosed with GIST should get treatment as soon as possible. Food Allergies Food allergies occur when the immune system thinks that a certain protein in any kind of food is a foreign substance and will try to fight against it.
Only about eight percent of children and two percent of adults actually have a food allergy. A person can be allergic to any kind of food, but the most common food allergies are to nuts, cow's milk, eggs, soy, fish, and shellfish. Most people who have a food allergy are allergic to fewer than four different foods. The most common signs of food allergies are hives, swelling, itchy skin, itchiness, tingling or swelling in the mouth, coughing, trouble breathing, diarrhea, and vomiting.
The two most common chronic illness that are associated with food allergies are eczema and asthma. Food allergies can be fatal if they cause the reaction called anaphylaxis. This reaction makes it hard for the person to breathe. This can be treated by an epinephrine injection. When this happens, contents from the stomach, called reflux, leak back into the esophagus and the stomach. When the stomach refluxes, stomach acid touches the lining of the esophagus and causes it to have a burning feeling in the throat or the chest.
This is what heartburn is. When you taste the fluid in the back of your throat, it is called acid indigestion. It is common for a person to get occasional heartburn, but when it occurs more than twice a week it can be considered to be GERD.
GERD can occur in people of all ages including infants. Some symptoms of GERD include having a pain in your chest, hoarseness, having trouble swallowing, or having the feeling of food being stuck in your throat.
The main symptoms are having persistent heartburn and acid regurgitation. GERD can also cause bad breath and a dry cough.
No one knows why people get GERD. Some things that could contribute to GERD are alcohol use, pregnancy, being overweight and smoking. Certain foods might also contribute like citrus fruits, caffeine, spicy, fatty, and dried foods, and also mint flavorings. Over-the-counter antacids or medications that help stop acid production and help the muscles empty the stomach are commonly used to treat GERD. Constipation Not everyone is on the same schedule for having a bowel movement.
Depending on the person, a "normal" schedule can range anywhere from three times a day to three times a week. If you start having bowel movements less than your own personal schedule, then you might be getting the signs of constipation. Constipation is when you have trouble having bowel movements. The stool is very hard, making it difficult to pass and causing a person to strain. You may even feel like you have to have a bowel movement even after you have already had one.
When you digest food, the waste products go through your intestines by the muscles contracting. When in the large intestine, most of the water and salt from the waste products are reabsorbed because they are needed by the body for our everyday functions.
Bile Duct Diseases
You can become constipated if too much water is absorbed, or if waste products move too slowly. Not getting enough fluids, a low fiber diet, age, not being physically active, depression, stress and pregnancy can all contribute to constipation.
Medications and narcotics can also cause a person to get constipated. Chronic constipation may be a symptom of a liver problem such as a urea cycle disorder. The best way for a person to treat constipation is to make sure that they are getting enough fluids as well as fiber in their diet. By doing this, the bulk of their stool is increased and made softer, so that it can move through the intestines more easily.
Being more active and increasing daily exercise also helps keep bowel movements regulated. Hemorrhoids Hemorrhoids also known as haemorrhoids, emerods, or piles are varicosities or swelling and inflammation of veins in the rectum and anus. Two of the most common types of hemorrhoids are external and internal hemorrhoids. The gastrointestinal tract is sensitive to emotion. Anger, anxiety, sadness, elation — all of these feelings and others can trigger symptoms in the gut.
The brain has a direct effect on the stomach and intestines. For example, the very thought of eating can release the stomach's juices before food gets there.
This connection goes both ways. A troubled intestine can send signals to the brain, just as a troubled brain can send signals to the gut. Therefore, a person's stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression. That's because the brain and the gastrointestinal GI system are intimately connected.
This is especially true in cases where a person experiences gastrointestinal upset with no obvious physical cause. For such functional GI disorders, it is difficult to try to heal a distressed gut without considering the role of stress and emotion. Gut health and anxiety Given how closely the gut and brain interact, it becomes easier to understand why you might feel nauseated before giving a presentation, or feel intestinal pain during times of stress.
That doesn't mean, however, that functional gastrointestinal conditions are imagined or "all in your head. Psychosocial factors influence the actual physiology of the gut, as well as symptoms.