41 terms

Anatomy and Physiology: Digestive System

Digestive System
refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. Aids in digestion.
(gastrointestinal tract)
(alimentary canal)
the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.
when food enters the mouth, being chewed by teeth, with chemical processing beginning with chemicals in the saliva from the salivary glands.
the thick liquid that results from a couple of hours submerged in hydrochloric acid in the stomach. It then goes through the small intestine, where the nutrients are absorbed.
the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material (feces) from the digestive tract via the anus. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum.
the anterior part of the alimentary canal, from the mouth to the duodenum at the entrance of the bile duct. At this point it is continuous with the midgut.
the first portion of the alimentary canal that receives food and saliva.
is the watery substance produced in the mouths of humans and most other animals. As part of the initial process of food digestion, the enzymes in the saliva break down some of the starch and fat in the food at the molecular level.
an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing food passes from the mouth through the pharynx into the esophagus and travels via peristalsis (radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube) to the stomach. The entry to the esophagus opens only when swallowing or vomiting.
a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract. The stomach is located between the esophagus and the small intestine. It secretes protein-digesting enzymes and strong acids to aid in food digestion, (sent to it via oesophageal peristalsis) through smooth muscular contortions (called segmentation) before sending partially digested food (chyme) to the small intestines.
A section of the stomach where the contents of the esophagus empty into the stomach.
A section of the stomach formed by the upper curvature of the organ.
A section of the stomach the main, central region.
A section of the stomach the lower section of the organ that facilitates emptying the contents into the small intestine.
the first section of the small intestine; may be the principal site for iron absorption. It is the shortest part of the small intestine, where most chemical digestion takes place. The duodenum is a hollow jointed tube about 10-12 inch long connecting the stomach to the jejunum.
Duodenum (First Part)
the first (superior) part begins as a continuation of the duodenal end of the pylorus.
Duodenum (Second Part)
the second (descending) part of the duodenum begins at the superior duodenal flexure. The pancreatic duct and common bile duct enter the descending duodenum, commonly known together as the hepatopancreatic duct (or pancreatic duct). The junction between the embryological foregut and midgut lies just below the major duodenal papilla.
a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion. It produces bile, an alkaline compound which aids in digestion via the emulsification (the process of making a mixture of two or more liquids which are normally immiscible (un-blendable)) of lipids. The liver's highly specialized tissues regulate a wide variety of high-volume biochemical reactions, including the synthesis and breakdown of small and complex molecules, many of which are necessary for normal vital functions.
a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. The gallbladder is a hollow system that sits just beneath the liver, and is divided into three sections: fundus, body and neck.
a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist the absorption of nutrients and the digestion in the small intestine. These enzymes help to further break down the carbohydrates, proteins, and lipids in the chyme.
an organ found in virtually all vertebrate animals with important roles in regard to red blood cells (also referred to as erythrocytes) and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock while also recycling iron. (Note that it is located in the foregut region, but is not a gut organ)
Celiac Trunk
is the first major branch of the abdominal aorta. The celiac artery supplies oxygenated blood to the liver, stomach, abdominal esophagus, spleen and the superior half of both the duodenum and the pancreas. These structures correspond to the embryonic foregut. Obstruction of the celiac artery will lead to necrosis of the structures it supplies.
Left Gastric Artery
arises from the celiac artery, and runs along the superior portion of the lesser curvature of the stomach. Branches also supply the lower esophagus. The left gastric artery anastomoses with the right gastric artery, which runs right to left.
Common Hepatic Artery
a short blood vessel that supplies oxygenated blood to the liver, pylorus (a part of the stomach), duodenum (a part of the small intestine) and pancreas.
Hepatic Artery Proper
arises from the common hepatic artery and runs alongside the portal vein and the common bile duct to form the portal triad. The hepatic artery proper gives off a small supraduodenal artery to the duodenal bulb.
Gastroduodenal Artery
a small blood vessel in the abdomen. It supplies blood directly to the pylorus (distal part of the stomach) and proximal part of the duodenum, and indirectly to the pancreatic head.
Splenic Artery
the blood vessel that supplies oxygenated blood to the spleen. It branches from the celiac artery, and follows a course superior to the pancreas.
Pancreatic Branches of Splenic Artery
numerous small vessels derived from the splenic artery as it runs behind the upper border of the pancreas, supplying its body and tail. One of these, larger than the rest, is sometimes given off near the tail of the pancreas; it runs from left to right near the posterior surface of the gland, following the course of the pancreatic duct, and is called the arteria pancreatica magna.
Short Gastric Arteries
consist of from five to seven small branches, which arise from the end of the splenic artery, and from its terminal divisions. They pass from left to right, between the layers of the gastrolienal ligament, and are distributed to the greater curvature of the stomach.
Left Gastro-omental Artery
the largest branch of the splenic artery, runs from left to right about a finger's breadth or more from the greater curvature of the stomach and between the layers of the greater omentum. In its course it distributes:
"Gastric branches": several ascending branches to both surfaces of the stomach;
"Omental branches": descend to supply the greater omentum.
Posterior Gastric
branch of splenic artery that leads to the posterior of stomach and the gastric region superior to the splenic artery.
Hepatic Portal System
responsible for directing blood from parts of the gastrointestinal tract to the liver. Substances absorbed in the small intestine travel first to the liver for processing before continuing to the heart. Not all of the gastrointestinal tract is part of this system. The system extends from about the lower portion of the esophagus to the upper part of the anal canal. It also includes venous drainage from the spleen and pancreas.
Hepatic Portal Vein
a vessel in the abdominal cavity that drains blood from the gastrointestinal tract and spleen to capillary beds in the liver. A major component of the hepatic portal system, it originates behind the neck of the pancreas. In most individuals, the hepatic portal vein is formed by the union of the superior mesenteric vein and the splenic vein. For this reason, the hepatic portal vein is occasionally called the splenic-mesenteric confluence.
(not a true vein, because it does not conduct blood directly to the heart)
Splenic Vein
the blood vessel that drains blood from the spleen. It joins with the superior mesenteric vein, to form the hepatic portal vein and follows a course superior to the pancreas, alongside of the similarly named artery, the splenic artery. It collects branches from the stomach and pancreas and most notably from the large intestine, which is drained by the inferior mesenteric vein and joins with splenic vein shortly before it forms the portal vein.
Superior Mesenteric Vein
a blood vessel that drains blood from the small intestine (jejunum and ileum). At its termination behind the neck of the pancreas, the SMV combines with the splenic vein to form the hepatic portal vein. The SMV lies to the right of the similarly named artery, the superior mesenteric artery, which originates from the abdominal aorta. Tributaries of the superior mesenteric vein drain the small intestine, large intestine, stomach, pancreas and appendix.
Inferior Mesenteric Vein
a blood vessel that drains blood from the large intestine. It usually terminates when reaching the splenic vein, which goes on to form the portal vein with the superior mesenteric vein. Tributaries of the inferior mesenteric vein drain the large intestine, sigmoid colon, and rectum.
the portion of the embryo from which most of the intestines develop. It comprises the portion of the alimentary canal from the end of the foregut at the opening of the bile duct to the hindgut, about two-thirds of the way through the transverse colon.
Duodenum (Third Part)
the third (inferior/horizontal) part of the duodenum begins at the inferior duodenal flexure.
Duodenum (Fourth Part)
the fourth (ascending) part curves anteriorly and terminates at the duodenojejunal flexure where it joins the jejunum.
the middle section of the small intestine. The jejunum lies between the duodenum and the ileum. In adult humans, the small intestine is usually between 5.5 and 6m long, 2.5m of which is the jejunum. The jejunum and the ileum are suspended by mesentery which gives the bowel great mobility within the abdomen. It also contains circular and longitudinal smooth muscle which helps to move food along by a process known as peristalsis.
Ligament of Treitz
The Suspensory muscle of duodenum or Ligament of Treitz (named after Václav Treitz) connects the duodenum of the small intestines to the diaphragm. This ligament is an important anatomical landmark of the duodenojejunal junction. This is actually a thin muscle that wraps around the small intestine where the duodenum and jejunum meet. It passes behind the pancreas and is attached above to the spine and the diaphragm.
(Suspensory muscle of duodenum)