Digestive System Your digestive system is uniquely constructed to perform its specialized function of turning food into the energy you need to survive and packaging the residue for waste disposal.
Parts and Functions of the Digestive System
Mouth The mouth is the beginning of the digestive tract; and, in fact, digestion starts here when taking the first bite of food. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.
Esophagus Located in your throat near your trachea (windpipe), the esophagus receives food from your mouth when you swallow. By means of a series of muscular contractions called peristalsis, the esophagus delivers food to your stomach.
Stomach The stomach is a hollow organ, or "container," that holds food while it is being mixed with enzymes that continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are sufficiently processed, they are released into the small intestine.
Small intestine the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food through and mixing it with digestive secretions from the pancreas and liver Made up of three segments- the duodenum, jejunum, and ileum .
Pancreas The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar.
Liver The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. In addition, the liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs.
Gallbladder The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats.
Colon (large intestine) The colon is a 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum. The appendix is a small tube attached to the cecum. The large intestine is a highly specialized organ that is responsible for processing waste so that emptying the bowels is easy and convenient.
Rectum The rectum (Latin for "straight") is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. If they can, the sphincters relax and the rectum contracts, disposing its contents. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away.
Anus The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is specialized to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid. The anus is surrounded by sphincter muscles that are important in allowing control of stool. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The internal sphincter is always tight, except when stool enters the rectum. It keeps us continent when we are asleep or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to hold the stool until reaching a toilet, where it then relaxes to release the contents.
Diseases in the Digestive System
1. Abdominal Adhesions Abdominal adhesions are bands of tissue that form between abdominal tissues and organs. Normally, internal tissues and organs have slippery surfaces, which allow them to shift easily as the body moves. Adhesions cause tissues and organs to stick together.
Causes Abdominal surgery is the most frequent cause of abdominal adhesions. Almost everyone who undergoes abdominal surgery develops adhesions; however, the risk is greater after operations on the lower abdomen and pelvis, including bowel and gynecological surgeries. Adhesions can become larger and tighter as time passes, causing problems years after surgery. Surgery-induced causes of abdominal adhesions include tissue incisions, especially those involving internal organs the handling of internal organs the drying out of internal organs and tissues contact of internal tissues with foreign materials, such as gauze, surgical gloves, and stitches blood or blood clots that were not rinsed out during surgery
Prevention Abdominal adhesions are difficult to prevent; however, surgical technique can minimize adhesions. Laparoscopic surgery avoids opening up the abdomen with a large incision. Instead, the abdomen is inflated with gas while special surgical tools and a video camera are threaded through a few, small abdominal incisions. Inflating the abdomen gives the surgeon room to operate. If a large abdominal incision is required, a special filmlike material (Seprafilm) can be inserted between organs or between the organs and the abdominal incision at the end of surgery. The filmlike material, which looks similar to wax paper, is absorbed by the body in about a week. Other steps during surgery to reduce adhesion formation include using starch- and latex-free gloves, handling tissues and organs gently, shortening surgery time, and not allowing tissues to dry out.
2.Bacteria and Foodborne Illness Foodborne illnesses are caused by eating food or drinking beverages contaminated with bacteria, parasites, or viruses. Harmful chemicals can also cause foodborne illnesses if they have contaminated food during harvesting or processing. Foodborne illnesses can cause symptoms that range from an upset stomach to more serious symptoms, including diarrhea, fever, vomiting, abdominal cramps, and dehydration. Most foodborne infections are undiagnosed and unreported, though the Centers for Disease Control and Prevention estimates that every year about 76 million people in the United States become ill from pathogens, or disease-causing substances, in food. Of these people, about 5,000 die.
Causes Harmful bacteria are the most common cause of foodborne illnesses. Some bacteria may be present on foods when you purchase them. Raw foods are the most common source of foodborne illnesses because they are not sterile; examples include raw meat and poultry that may have become contaminated during slaughter. Seafood may become contaminated during harvest or through processing. One in 10,000 eggs may be contaminated with Salmonella inside the egg shell. Produce such as spinach, lettuce, tomatoes, sprouts, and melons can become contaminated with Salmonella, Shigella, or Escherichia coli (E. coli) O157:H7. Contamination can occur during growing, harvesting, processing, storing, shipping, or final preparation. Sources of produce contamination are varied as these foods are grown in soil and can become contaminated during growth or through processing and distribution. Contamination may also occur during food preparation in a restaurant or a home kitchen. The most common form of contamination from handled foods is the calcivirus, also called the Norwalk-like virus.
When food is cooked and left out for more than 2 hours at room temperature, bacteria can multiply quickly. Most bacteria grow undetected because they don’t produce a bad odor or change the color or texture of the food. Freezing food slows or stops bacteria’s growth but does not destroy the bacteria. The microbes can become reactivated when the food is thawed. Refrigeration also can slow the growth of some bacteria. Thorough cooking is needed to destroy the bacteria.
Treatment Most cases of foodborne illnesses are mild and can be treated by increasing fluid intake, either orally or intravenously, to replace lost fluids and electrolytes. People who experience gastrointestinal or neurologic symptoms should seek medical attention. In the most severe situations, such as HUS, hospitalization may be needed to receive supportive nutritional and medical therapy. Maintaining adequate fluid and electrolyte balance and controlling blood pressure are important. Doctors will try to minimize the impact of reduced kidney function. Dialysis may be needed until the kidneys can function normally. Blood transfusions also may be needed.
3. Appendecitis Appendicitis is a painful swelling and infection of the appendix.
Causes Obstruction of the appendiceal lumen causes appendicitis. Mucus backs up in the appendiceal lumen, causing bacteria that normally live inside the appendix to multiply. As a result, the appendix swells and becomes infected. Sources of obstruction include feces, parasites, or growths that clog the appendiceal lumen enlarged lymph tissue in the wall of the appendix, caused by infection in the gastrointestinal tract or elsewhere in the body inflammatory bowel disease, including Crohn’s disease and ulcerative colitis trauma to the abdomen An inflamed appendix will likely burst if not removed. Bursting spreads infection throughout the abdomen—a potentially dangerous condition called peritonitis.
Treatment Typically, appendicitis is treated by removing the appendix. If appendicitis is suspected, a doctor will often suggest surgery without conducting extensive diagnostic testing. Prompt surgery decreases the likelihood the appendix will burst. Surgery to remove the appendix is called appendectomy and can be done two ways. The older method, called laparotomy, removes the appendix through a single incision in the lower right area of the abdomen. The newer method, called laparoscopic surgery, uses several smaller incisions and special surgical tools fed through the incisions to remove the appendix. Laparoscopic surgery leads to fewer complications, such as hospital-related infections, and has a shorter recovery time
Surgery occasionally reveals a normal appendix. In such cases, many surgeons will remove the healthy appendix to eliminate the future possibility of appendicitis. Occasionally, surgery reveals a different problem, which may also be corrected during surgery. Sometimes an abscess forms around a burst appendix—called an appendiceal abscess. An abscess is a pus-filled mass that results from the body’s attempt to keep an infection from spreading. An abscess may be addressed during surgery or, more commonly, drained before surgery. To drain an abscess, a tube is placed in the abscess through the abdominal wall. CT is used to help find the abscess. The drainage tube is left in place for about 2 weeks while antibiotics are given to treat infection. Six to 8 weeks later, when infection and inflammation are under control, surgery is performed to remove what remains of the burst appendix.
4. BiliaryAtresia Biliaryatresia is a serious but rare disease of the liver that affects newborn infants. It occurs in about one in 10,000 children and is more common in girls than in boys and in Asian and African-American newborns than in Caucasian newborns. The cause of biliaryatresia is not known, and treatments are only partially successful. Biliaryatresia is the most common reason for liver transplantation in children in the United States and most of the Western world. The liver damage incurred from biliaryatresia is caused by injury and loss (atresia) of the bile ducts that are responsible for draining bile from the liver. Bile is made by the liver and passes through the bile ducts and into the intestines where it helps digest food, fats, and cholesterol. The loss of bile ducts causes bile to remain in the liver. When bile builds up it can damage the liver, causing scarring and loss of liver tissue. Eventually the liver will not be able to work properly and cirrhosis will occur. Once the liver fails, a liver transplant becomes necessary. Biliaryatresia can lead to liver failure and the need for liver transplant within the first 1 to 2 years of life.
Causes The cause of biliaryatresia is not known. The two types of biliaryatresia appear to be a “fetal” form, which arises during fetal life and is present at the time of birth, and a “perinatal” form, which is more typical and does not become evident until the second to fourth week of life. Some children, particularly those with the fetal form of biliaryatresia, often have other birth defects in the heart, spleen, or intestines. An important fact is that biliaryatresia is not an inherited disease. Cases of biliaryatresia do not run in families; identical twins have been born with only one child having the disease. Biliaryatresia is most likely caused by an event occurring during fetal life or around the time of birth. Possibilities for the “triggering” event may include one or a combination of the following factors: infection with a virus or bacterium a problem with the immune system an abnormal bile component an error in development of the liver and bile ducts Research on the cause of biliaryatresia is of great importance. Progress in the management and prevention of biliaryatresia can only come from a better understanding of its cause or causes.
Treatment Surgery. If biliaryatresia appears to be the cause of the jaundice in the newborn, the next step is surgery. At the time of surgery the bile ducts can be examined and the diagnosis confirmed. For this procedure, the infant is sedated. While the infant is asleep, the surgeon makes an incision in the abdomen to directly examine the liver and bile ducts. If the surgeon confirms that biliaryatresia is the problem, a Kasai procedure will usually be performed on the spot.
5. Bleeding in the Digestive Tract Bleeding in the digestive tract is a symptom of a disease rather than a disease itself. A number of different conditions can cause bleeding. Most causes of bleeding are related to conditions that can be cured or controlled, such as ulcers or hemorrhoids. Some causes of bleeding may be life threatening.
Causes A variety of conditions can cause bleeding in the digestive tract. Causes of bleeding in the upper digestive tract include the following: Peptic ulcers.Helicobacter pylori (H. pylori) infections and long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, are common causes of peptic ulcers. Esophageal varices.Varices, or enlarged veins, located at the lower end of the esophagus may rupture and bleed massively. Cirrhosis is the most common cause of esophageal varices. Mallory-Weiss tears. These tears in the lining of the esophagus usually result from vomiting. Increased pressure in the abdomen from coughing, hiatal hernia, or childbirth can also cause tears. Gastritis. NSAIDs and other drugs, infections, Crohn’s disease, illnesses, and injuries can cause gastritis—inflammation and ulcers in the lining of the stomach. Esophagitis.Gastroesophageal reflux disease (GERD) is the most common cause of esophagitis—inflammation and ulcers in the lining of the esophagus. In GERD, the muscle between the esophagus and stomach fails to close properly, allowing food and stomach juices to flow back into the esophagus. Benign tumors and cancer. A benign tumor is an abnormal tissue growth that is not cancerous. Benign tumors and cancer in the esophagus, stomach, or duodenum may cause bleeding.
Treatment Endoscopy can be used to stop bleeding in the digestive tract. A doctor can insert tools through the endoscope to inject chemicals into the bleeding site treat the bleeding site and surrounding tissue with a heat probe, electric current, or laser close affected blood vessels with a band or clip
6. Cirrhosis Cirrhosis is a condition in which the liver slowly deteriorates and malfunctions due to chronic injury. Scar tissue replaces healthy liver tissue, partially blocking the flow of blood through the liver. Scarring also impairs the liver’s ability to control infections remove bacteria and toxins from the blood process nutrients, hormones, and drugs make proteins that regulate blood clotting produce bile to help absorb fats—including cholesterol—and fat-soluble vitamins
Causes Cirrhosis has various causes. In the United States, heavy alcohol consumption and chronic hepatitis C have been the most common causes of cirrhosis. Obesity is becoming a common cause of cirrhosis, either as the sole cause or in combination with alcohol, hepatitis C, or both. Many people with cirrhosis have more than one cause of liver damage. Cirrhosis is not caused by trauma to the liver or other acute, or short-term, causes of damage. Usually years of chronic injury are required to cause cirrhosis.
Treatment Treatment for cirrhosis depends on the cause of the disease and whether complications are present. The goals of treatment are to slow the progression of scar tissue in the liver and prevent or treat the complications of the disease. Hospitalization may be necessary for cirrhosis with complications. Eating a nutritious diet. Because malnutrition is common in people with cirrhosis, a healthy diet is important in all stages of the disease. Health care providers recommend a meal plan that is well balanced. If ascites develops, a sodium-restricted diet is recommended. A person with cirrhosis should not eat raw shellfish, which can contain a bacterium that causes serious infection. To improve nutrition, the doctor may add a liquid supplement taken by mouth or through a nasogastric tube—a tiny tube inserted through the nose and throat that reaches into the stomach.
7. Esophageal Ring
Esophageal ring or Schatzki’s ring is a thin band of tissue that encircles the lining of the esophagus. Sometimes, this band of tissue is thicker and more fibrous, but narrower than a ring – here, it is called an esophageal web.
Causes Esophageal webs are caused by: Iron-deficiency anemia Graft-vs-host diseaseThis is a disease resulting from bone marrow transplantation Postcricoid cancerA rare form of cancer located in the upper portion of the esophagus.
Treatment Esophageal rings and webs usually respond well to the following treatments: BougieA bougie (“boojie”) is a tapered device made of rubber that is used to flatten the tissue of the esophagus and to enlarge its opening. Pneumatic dilatorA balloon is placed on the narrowed portion of the esophagus and then inflated.
8. Esophageal Stricture (Stenosis) Esophageal stricture or stenosis is the narrowing of the esophagus caused by a scar or cancer.
Causes Causes of esophageal stricture include: Gastroesophageal reflux diseaseEsophageal stricture commonly develops after gastroesophageal reflux disease or GERD, caused by chronic tissue injury because of stomach acid backing up into the esophagus. Toxic or caustic chemicalsSwallowing toxic or caustic chemicals can cause injury to the tissue which heals with a fibrous scar tissue.
Treatment To treat stricture, various techniques below are used to enlarge the narrowed opening of the esophagus: BougieA bougie (“boojie”) is a tapered rubber device that flattens the tissue and enlarges the opening of the esophagus. Pneumatic dilatorA balloon is placed on the narrowed portion and then inflated.
9.Gastritis Gastritis is the inflammation of the lining of the stomach. This condition can be an acute (with rapid onset, short period, and usually severe intensity) or a chronic condition.
Causes The causes of gastritis include: H. pylori infection Non-steroidal anti-inflammatory drugs (NSAIDs)These are painkillers that can reduce the protective nature of the stomach lining against the digestive acids and enzymes in the stomach. Drinking alcoholic beveragesAlcohol stimulates the production of stomach acid and large doses of alcohol can damage and inflame the stomach.
Treatment Gastritis is treated with: AntibioticsIf H. pylori is present, antibiotics are prescribed to eliminate this bacteria. Medications to reduce stomach acidThese include: Histamine or H2 blockers, which prevents the histamine receptors from stimulating the production of stomach acids Proton pump inhibitors, which stop stomach acid production.
10. Mesenteric Ischemia Mesenteric ischemia is the damage to the tissue of the intestine caused by acute or sudden as well as chronic lack of blood supply to the specific area. It can be though of as the intestinal equivalence of a heart attack, caused by blood clots in the arteries that supply blood to the heart.
Causes Mesenteric ischemia is caused by intestinal tissue damage due to lack of blood supply to the area. Blood flow is interrupted by plaques or clots that form in the arteries – which may cause an acute or sudden and severe loss of flow, or a chronic condition where the blood flow is severely reduced. The process of plaque or clotformation, called artherosclerosis, is quite complex and involves many factors including genetics, diets, cholesterol and triglycerides levels.
Treatment The treatments for this condition include: SurgeryIf the angiogram shows a specific clot or blockage, then an emergency surgery may be required. Surgery may also be necessary if significant tissue d amage has already occurred. AngioplastyA baloon is threaded through the artery and is inflated at the location of the blockage to restore blood flow. Vasodilator medicationMedicines that dilate the arteries, such as papaverine, is given intravenously to open the clot.
How to care for the Digestive System
1) Eat right. Consume protein, carbohydrates and fat in the right amounts and make sure you get plenty of fiber. Eat on a regular schedule. 2) Drink plenty of water and avoid sugary drinks or those that contain caffeine. Limit alcoholic drinks to 2 a day. 3) Exercise. Moving around helps things move along.
4) Be alert for problems that don't go away. Symptoms such as heartburn, constipation and stomach upset can be caused by things as minor as a bad chili dog or as serious as cancer. If you've been suffering for more than a couple of weeks, see your doctor. 5) Get scheduled tests. Your doctor will tell you when you need to have regular colonoscopies to find and remove precancerous polyps. If your doctor recommends other tests, get those as well. 6) Quit smoking. Among the many reasons to quit smoking, it contributes to digestive problems such as heartburn, ulcers and gallstones.
Project in Science II Digestive System Submitted to: Mrs. Ma. Regina B. Escleva Submitted by: