Digestive System

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Digestive diseases
It was the findings in , describing the first olfactory receptors that helped to prompt the research into taste. It connects to the duodenum via the pancreatic duct which it joins near to the bile duct's connection where both the bile and pancreatic juice can act on the chyme that is released from the stomach into the duodenum. The gallbladder is a hollow part of the biliary tract that sits just beneath the liver, with the gallbladder body resting in a small depression. The mouth and stomach are also responsible for the storage of food as it is waiting to be digested. Stomodeum Buccopharyngeal membrane Rathke's pouch Tracheoesophageal septum Pancreatic bud Hepatic diverticulum. From Wikipedia, the free encyclopedia. It is stimulated by distension of the stomach, presence of food in stomach and decrease in pH.

Digestive System Physiology

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Made up of three segments, the duodenum, jejunum, and ileum, the small intestine is a long tube loosely coiled in the abdomen spread out, it would be more than 20 feet long. The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile from the liver.

Bile is a compound that aids in the digestion of fat and eliminates waste products from the blood. Peristalsis contractions is also at work in this organ, moving food through and mixing it up with digestive secretions. The duodenum is largely responsible for continuing the process of breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

Three organs play a pivotal role in helping the stomach and small intestine digest food:. Among other functions, the oblong pancreas secretes enzymes into the small intestine. These enzymes break down protein, fat, and carbohydrates from the food we eat. The liver has many functions, but two of its main functions within the digestive system are to make and secrete bile, and to cleanse and purify the blood coming from the small intestine containing the nutrients just absorbed. The gallbladder is a pear-shaped reservoir that sits just under the liver and stores bile.

Bile is made in the liver then if it needs to be stored travels to the gallbladder through a channel called the cystic duct. During a meal, the gallbladder contracts, sending bile to the small intestine. Once the nutrients have been absorbed and the leftover liquid has passed through the small intestine, what is left of the food you ate is handed over to the large intestine, or colon.

The colon is a 5- to 6-foot-long muscular tube that connects the cecum the first part of the large intestine to the rectum the last part of the large intestine. It is made up of the cecum, the ascending right colon, the transverse across colon, the descending left colon, and the sigmoid colon so-called for its "S" shape; the Greek letter for S is called the sigma , which connects to the rectum.

Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis contractions , first in a liquid state and ultimately in solid form as the water is removed from the stool. A stool is stored in the sigmoid colon until a "mass movement" empties it into the rectum once or twice a day. It normally takes about 36 hours for stool to get through the colon.

The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins , processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, or feces, it empties its contents into the rectum to begin the process of elimination. 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 you know 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 muscles relax and the rectum contracts, expelling its contents. If the contents cannot be expelled, the sphincters contract and the rectum accommodates, so that the sensation temporarily goes away.

The anus is the last part of the digestive tract. The treatment of food in the digestive system involves the following seven processes: Propulsion is the movement of food along the digestive tract. The major means of propulsion is peristalsis, a series of alternating contractions and relaxations of smooth muscle that lines the walls of the digestive organs and that forces food to move forward.

Secretion of digestive enzymes and other substances liquefies, adjusts the pH of, and chemically breaks down the food. Mechanical digestion is the process of physically breaking down food into smaller pieces. This process begins with the chewing of food and continues with the muscular churning of the stomach.

Additional churning occurs in the small intestine through muscular constriction of the intestinal wall. This process, called segmentation, is similar to peristalsis, except that the rhythmic timing of the muscle constrictions forces the food backward and forward rather than forward only.

Chemical digestion is the process of chemically breaking down food into simpler molecules. The process is carried out by enzymes in the stomach and small intestines. Absorption is the movement of molecules by passive diffusion or active transport from the digestive tract to adjacent blood and lymphatic vessels. Absorption is the entrance of the digested food now called nutrients into the body. Removing book from your Reading List will also remove any bookmarked pages associated with this title.

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