Epithelium Study Guide

Get FREE Access!

Gastrointestinal tract
The latter has the diameter of around 2. Among other crucial functions, the small intestine also helps in the bowel movements to expel digestive waste towards the posterior end of the digestive tract for its ultimate removal out of the body. The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. It connects the throat above with the stomach below. The small intestine histology is both complex and interesting. Over-the-counter and prescription medicines can soften the stool and reduce constipation.

What is Small Intestine?

Absorption Disorders Overview, Types

If anything goes awry in any stage of this process, malabsorption results. The digestive process begins as soon as food enters your mouth. The enzymes in your saliva and the process of chewing change the bite of food into a bolus -- chewed but undigested food matter. When you swallow, your throat thrusts the bolus into your esophagus, where the muscular contractions of its walls pass it to the stomach.

When the bolus enters the stomach, acids and enzymes churn it into smaller bits of food. Only after the matter enters the small intestine and goes through the three stages of absorption does the bite of food you ingested break into individual molecules small enough to pass through the wall of your small intestine and provide nourishment to your body.

A number of conditions can cause a failure in the process of absorption. These include illness, medication, trauma and genetically-linked conditions. If you fail to absorb the nutrients in the food you eat, health issues arise. Some forms of malabsorption apply to most nutrients while others affect a particular one. The most common form of malabsorption, celiac disease, occurs in people who cannot digest gluten, a protein found in wheat, barley and rye grains.

However, malabsorption can occur as a result of obstruction or disease of the gall bladder, liver failure, pancreatic disease, abnormal bowel mobility, overgrowth of bacteria and many other maladies and anomalies. The number one symptom of the malabsorption of protein is edema.

It carries swallowed masses of chewed food along its length. At the inferior end of the esophagus is a muscular ring called the lower esophageal sphincter or cardiac sphincter. The function of this sphincter is to close of the end of the esophagus and trap food in the stomach. The stomach is a muscular sac that is located on the left side of the abdominal cavity, just inferior to the diaphragm.

In an average person, the stomach is about the size of their two fists placed next to each other. This major organ acts as a storage tank for food so that the body has time to digest large meals properly. The stomach also contains hydrochloric acid and digestive enzymes that continue the digestion of food that began in the mouth. It is located just inferior to the stomach and takes up most of the space in the abdominal cavity. The entire small intestine is coiled like a hose and the inside surface is full of many ridges and folds.

These folds are used to maximize the digestion of food and absorption of nutrients. The liver is a roughly triangular accessory organ of the digestive system located to the right of the stomach, just inferior to the diaphragm and superior to the small intestine. The liver weighs about 3 pounds and is the second largest organ in the body. The liver has many different functions in the body, but the main function of the liver in digestion is the production of bile and its secretion into the small intestine.

The gallbladder is a small, pear-shaped organ located just posterior to the liver. The gallbladder is used to store and recycle excess bile from the small intestine so that it can be reused for the digestion of subsequent meals. The pancreas is a large gland located just inferior and posterior to the stomach. The pancreas secretes digestive enzymes into the small intestine to complete the chemical digestion of foods. The large intestine is a long, thick tube about 2.

It is located just inferior to the stomach and wraps around the superior and lateral border of the small intestine. The large intestine absorbs water and contains many symbiotic bacteria that aid in the breaking down of wastes to extract some small amounts of nutrients. Feces in the large intestine exit the body through the anal canal.

The digestive system is responsible for taking whole foods and turning them into energy and nutrients to allow the body to function, grow, and repair itself. The six primary processes of the digestive system include:.

Colonoscopy can remove polyps as small as one millimetre or less. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. It takes 15 years or less for a polyp to turn cancerous. Colonoscopy is similar to sigmoidoscopy —the difference being related to which parts of the colon each can examine.

A sigmoidoscopy is often used as a screening procedure for a full colonoscopy, often done in conjunction with a fecal occult blood test FOBT. Virtual colonoscopy , which uses 2D and 3D imagery reconstructed from computed tomography CT scans or from nuclear magnetic resonance MR scans, is also possible, as a totally non-invasive medical test, although it is not standard and still under investigation regarding its diagnostic abilities.

If a growth or polyp is detected using CT colonography, a standard colonoscopy would still need to be performed. Additionally, surgeons have lately been using the term pouchoscopy to refer to a colonoscopy of the ileo-anal pouch. The large intestine is truly distinct only in tetrapods , in which it is almost always separated from the small intestine by an ileocaecal valve.

In most vertebrates, however, it is a relatively short structure running directly to the anus, although noticeably wider than the small intestine. Although the caecum is present in most amniotes , only in mammals does the remainder of the large intestine develop into a true colon. In some small mammals, the colon is straight, as it is in other tetrapods, but, in the majority of mammalian species, it is divided into ascending and descending portions; a distinct transverse colon is typically present only in primates.

However, the taeniae coli and accompanying haustra are not found in either carnivorans or ruminants. The rectum of mammals other than monotremes is derived from the cloaca of other vertebrates, and is, therefore, not truly homologous with the "rectum" found in these species. In fish, there is no true large intestine, but simply a short rectum connecting the end of the digestive part of the gut to the cloaca. In sharks , this includes a rectal gland that secretes salt to help the animal maintain osmotic balance with the seawater.

The gland somewhat resembles a caecum in structure, but is not a homologous structure. From Wikipedia, the free encyclopedia. Large intestine Front of abdomen , showing the large intestine, with the stomach and small intestine in gray outline. Front of abdomen, showing surface markings for liver red , and the stomach and large intestine blue. The large Intestine is like an upside down U. Development of the digestive system.

This section needs expansion. You can help by adding to it. Angiodysplasia of the colon Appendicitis Chronic functional abdominal pain Colitis Colorectal cancer Colorectal polyp Constipation Crohn's disease Diarrhea Diverticulitis Diverticulosis Hirschsprung's disease aganglionosis Ileus Intussusception Irritable bowel syndrome Pseudomembranous colitis Ulcerative colitis and toxic megacolon.

This article uses anatomical terminology; for an overview, see Anatomical terminology. Mosby's Medical Dictionary 8th ed. A Dictionary of Biology. Gray's Anatomy for Students. J Vis Exp Retrieved March 21, The Journal of Infectious Diseases. Clinical Anatomy for Medical Students 4 ed.

Little, Brown, and Company. Ask a Digestive System Specialist. Archived from the original on Above with active image links ". Retrieved 8 November Kochman 18 August The American Journal of Gastroenterology.

World J Gastrointest Oncol. Did it once have a purpose that has since been lost? Applied and Environmental Microbiology.

The American Journal of Clinical Nutrition. Journal of Lipid Research. Journal of General Internal Medicine. Retrieved Jun 15, Michael; Allen, Paul M. J Natl Cancer Inst. Anatomy of the gastrointestinal tract , excluding the mouth. Muscles Spaces peripharyngeal retropharyngeal parapharyngeal retrovisceral danger prevertebral Pterygomandibular raphe Pharyngeal raphe Buccopharyngeal fascia Pharyngobasilar fascia Piriform sinus. Sphincters upper lower glands. Suspensory muscle Major duodenal papilla Minor duodenal papilla Duodenojejunal flexure Brunner's glands.

Ileocecal valve Peyer's patches Microfold cell. Ascending colon Hepatic flexure Transverse colon Splenic flexure Descending colon Sigmoid colon Continuous taenia coli haustra epiploic appendix. Retrieved from " https: Wikipedia articles incorporating text from the 20th edition of Gray's Anatomy Digestive system Organs anatomy.

Pages with unresolved properties CS1 maint:

Types of Absorption Disorders