Anatomy of the Digestive System Glossary of Terms

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Abdomen: The belly, that part of the body that contains all of the structures between the chest and the pelvis. The abdomen is separated anatomically from the chest by the diaphragm, the powerful muscle spanning the body cavity below the lungs.
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Absorb: 1. To take something in, as through the skin or the intestine.
2. To react with radiation and reduce it in intensity, as with a dose of radiation or transmitted light.
See also: Absorbed dose; Absorption; Malabsorption; Reabsorption.

Absorption: Uptake. In the biomedical sciences, absorption has diverse specific meanings.
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Alimentary: Concerning food, nourishment, and the organs of digestion. From the Latin alimentum meaning nourishment.

Alimentary canal: The digestive tract. See: Gastrointestinal tract.

American Medical Association (AMA): The AMA. The AMA's mission statement proclaims:
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Amylase: An enzyme produced in the pancreas and salivary glands that helps in the digestion of starches. Elevation of blood amylase is common in pancreatitis.

Anatomy: The study of form. Gross anatomy involves structures that can be seen with the naked eye. It is as opposed to microscopic anatomy (or histology) which involves structures seen under the microscope. Traditionally, both gross and microscopic anatomy have been studied in the first year of medical school in the U.S. The most celebrated textbook of anatomy in the English-speaking world is Gray's Anatomy, still a useful reference book. The word "anatomy" comes from the Greek ana- meaning up or through + tome meaning a cutting. Anatomy was once a "cutting up" because the structure of the body was originally learned through dissecting it, cutting it up. The abbreviation for anatomy is anat.

Anus: The opening of the rectum to the outside of the body.
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Bacteria: Single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life).
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Bile: Bile is a yellow-green fluid that is made by the liver, stored in the gallbladder and passes through the common bile duct into the duodenum where it helps digest fat. The principal components of bile are cholesterol, bile salts, and the pigment bilirubin.
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Bladder: Any pouch or other flexible enclosure that can hold liquids or gases but usually refers to the hollow organ in the lower abdomen that stores urine -- the urinary bladder. The kidneys filter waste from the blood and produce urine, which enters the bladder through two tubes called ureters. Urine leaves the bladder through another tube, the urethra. In women, the urethra is a short tube that opens just in front of the vagina. In men, it is longer, passing through the prostate gland and then the penis. Infection of the bladder is called cystitis.

Bowel: Another name for the intestine. The small bowel and the large bowel are the small intestine and large intestine, respectively.
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Carbohydrates: Mainly sugars and starches, together constituting one of the three principal types of nutrients used as energy sources (calories) by the body. Carbohydrates can also be defined chemically as neutral compounds of carbon, hydrogen and oxygen.
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Cardiac: Having to do with the heart.

Cecum: The cecum (also spelled caecum), the first portion of the large bowel, situated in the lower right quadrant of the abdomen.
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Chyme: A pre-digested, acidified mass of food that passes from the stomach into the small intestine.

Colon: The part of the large intestine that runs from the cecum to the rectum as a long hollow tube that serves to remove water from digested food and let the remaining material, solid waste called stool, move through it to the rectum and leave the body through the anus. .
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Colonoscopy: A procedure in which a long flexible viewing tube (a colonoscope) is threaded up through the rectum for the purpose of inspecting the entire colon and rectum and, if there is an abnormality, taking a biopsy of it or removing it. The colonoscopy procedure requires a thorough bowel cleansing to assure a clear view of the lining. Called also coloscopy.

Digestive system: The organs that are responsible for getting food into and out of the body and for making use of it. These organs include the salivary glands, the mouth, esophagus, stomach, small intestine, liver, gallbladder, pancreas, colon, rectum, and anus.
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Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick. As a verb, to allow fluid to be released from a confined area.

Duodenum: The first part of the small intestine. The duodenum extends from the pylorus at the bottom of the stomach to the jejunum, the second part of the small intestine. The duodenum is a common site for the formation of peptic ulcers. We often live with words without thinking where they come from or what they originally meant. That is the case for me with the duodenum. For decades, this writer knew the duodenum as a short but troubled sector of the small intestine. Only today did I learn that the duodenum began as the dodeka-daktulon, twelve fingers to the Greeks, who astutely observed that the duodenum is about 12 finger-breadths long. In German, the popular term for duodenum is Zwolffingerdarm, the 12-finger intestine.

Endoscopy: Endoscopy is a broad term used to described examining the inside of the body using a lighted, flexible instrument called an endoscope. In general, an endoscope is introduced into the body through a natural opening like the mouth or anus. Although endoscopy can include examination of other organs, the most common endoscopic procedures evaluate the esophagus (swallowing tube), stomach, and portions of the intestine.

Enzyme: A protein (or protein-based molecule) that speeds up a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions, converting a specific set of reactants (called substrates) into specific products. Without enzymes, life as we know it would not exist.
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Enzymes: Proteins that act as a catalysts in mediating and speeding a specific chemical reaction.
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Epiglottis: The flap that covers the trachea during swallowing so that food does not enter the lungs.
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Esophagus: The tube that connects the pharynx (throat) with the stomach. The esophagus lies between the trachea (windpipe) and the spine. It passes down the neck, pierces the diaphragm just to the left of the midline, and joins the cardiac (upper) end of the stomach. In an adult, the esophagus is about 25 centimeters (10 inches) long. When a person swallows, the muscular walls of the esophagus contract to push food down into the stomach. Glands in the lining of the esophagus produce mucus, which keeps the passageway moist and facilitates swallowing. Also known as the gullet or swallowing tube. From the Greek oisophagos, from oisein meaning to bear or carry + phagein, to eat.

Fats: Plural of the word "fat". See the definition of fat.

Feces: The medical and scientific term for the "excrement discharged from the intestines."
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Gallbladder: A pear-shaped organ just below the liver that stores the bile secreted by the liver. During a fatty meal, the gallbladder contracts, delivering the bile through the bile ducts into the intestines to help with digestion. Abnormal composition of bile leads to formation of gallstones, a process termed cholelithiasis. The gallstones cause cholecystitis, inflammation of the gallbladder.

Gastric: Having to do with the stomach.

Gastroenterology: The medical specialty devoted to the study, diagnosis and treatment of disorders of the digestive system. These disorders may affect the esophagus (swallowing tube), stomach, small intestine, large intestine (colon), rectum, liver, gallbladder, or pancreas.
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Hepatology: The field of liver disease. The liver is the body's largest organ and hepatology is a large field. It includes, but is not limited to, the study of acute and chronic hepatitis, viral hepatitis, cirrhosis, genetic and metabolic liver diseases and their complications, liver cancer, liver transplantation, drug metabolism (which depends largely upon the liver), and immunology as it pertains to the liver.
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Ileum: The lowest part of the small intestine, located beyond the duodenum and jejunum, just before the large intestine (the colon). Pronounced "il-eum" in the US and "eye-leum" in the UK.
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Internal medicine: A medical specialty dedicated to the diagnosis and medical treatment of adults. A physician who specializes in internal medicine is referred to as an internist. A minimum of seven years of medical school and postgraduate training are focused on learning the prevention, diagnosis, and treatment of diseases of adults. Subspecialties of internal medicine include allergy and immunology, cardiology (heart), endocrinology (hormone disorders), hematology (blood disorders), infectious diseases, gastroenterology (diseases of the gut), nephrology (kidney diseases), oncology (cancer), pulmonology (lung disorders), and rheumatology (arthritis and musculoskeletal disorders).

Intestine: The long, tubelike organ in the abdomen that completes the process of digestion. It consists of the small and large intestines.

Jaw: The bones below the mouth (the mandible) and the bone above the mouth just above the mouth (the maxilla). The word jaw comes from the Anglo-Saxon ceowan meaning to chew.

Jejunum: Part of the small intestine. It is half-way down the small intestine between its duodenum and ileum sections.
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Large intestine: Comes after the small intestine. Large because it is wider than the small intestine.

Liver: An organ in the upper abdomen that aids in digestion and removes waste products and worn-out cells from the blood. The liver is the largest solid organ in the body. The liver weighs about three and a half pounds (1.6 kilograms). It measures about 8 inches (20 cm) horizontally (across) and 6.5 inches (17 cm) vertically (down) and is 4.5 inches (12 cm) thick.

Malabsorption: The impaired absorption by the intestines of nutrients from food. Malabsorption can be specific and involve sugars, fats, proteins, or vitamins. Alternatively, malabsorption can be general and nonspecific.
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Mouth: 1. The upper opening of the digestive tract, beginning with the lips and containing the teeth, gums, and tongue. Foodstuffs are broken down mechanically in the mouth by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch. 2. Any opening or aperture in the body. The mouth in both senses of the word is also called the os, the Latin word for an opening, or mouth. The o in os is pronounced as in hope. The genitive form of os is oris from which comes the word oral.

Muscular: Having to do with the muscles. Also, endowed with above average muscle development. Muscular system refers to all of the muscles of the body collectively.

Nutrition: 1) The science or practice of taking in and utilizing foods. 2) A nourishing substance, such as nutritional solutions delivered to hospitalized patients via an IV or IG tube.

Organ: A relatively independent part of the body that carries out one or more special functions. The organs of the human body include the eye, ear, heart, lungs, and liver.

Pancreas: A fish-shaped spongy grayish-pink organ about 6 inches (15 cm) long that stretches across the back of the abdomen, behind the stomach. The head of the pancreas is on the right side of the abdomen and is connected to the duodenum (the first section of the small intestine). The narrow end of the pancreas, called the tail, extends to the left side of the body.

Peristalsis: The rippling motion of muscles in the digestive tract. In the stomach, this motion mixes food with gastric juices, turning it into a thin liquid.

Pharmacy: A location where prescription drugs are sold. A pharmacy is, by law, constantly supervised by a licensed pharmacist.

Proteins: Large molecules composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.
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Rectum: The last 6 to 8 inches of the large intestine. The rectum stores solid waste until it leaves the body through the anus. The word rectum comes from the Latin rectus meaning straight (which the human rectum is not).

Saliva: a watery secretion in the mouth produced by the salivary glands that aids in the digestion of food. Saliva also serves to moisten and cleanse the mouth, including the tongue and teeth, and contains substances that can play a role in the prevention of infection. Saliva aids digestion by moistening food and contains enzymes that begin the digestion process. Also known as spit.

Small intestine: The part of the digestive tract that extends from the stomach to the large intestine.

Stomach: 1. The sac-shaped digestive organ that is located in the upper abdomen, under the ribs. The upper part of the stomach connects to the esophagus, and the lower part leads into the small intestine.
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Throat: The throat is the anterior (front) portion of the neck beginning at the back of the mouth, consisting anatomically of the pharynx and larynx. The throat contains the trachea and a portion of the esophagus.

Tongue: The tongue is a strong muscle anchored to the floor of the mouth. It is covered by the lingual membrane which has special areas to detect tastes.
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Trachea: A tube-like portion of the breathing or "respiratory" tract that connects the "voice box" (larynx) with the bronchial parts of the lungs.

Villi: Plural of villus, a tiny finger-like or vascular projection.

Windpipe: The trachea, a tube-like portion of the respiratory (breathing) tract that connects the larynx (the voicebox) with the bronchial parts of the lungs.