Which intestine is the last section of the digestive system

Your small intestine moves water from your bloodstream into your GI tract to help break down food. Your small intestine also absorbs water with other nutrients. In your large intestine, more water moves from your GI tract into your bloodstream. Bacteria in your large intestine help break down remaining nutrients and make vitamin K. Waste products of digestion, including parts of food that are still too large, become stool. The small intestine absorbs most of the nutrients in your food, and your circulatory system passes them on to other parts of your body to store or use.

Special cells help absorbed nutrients cross the intestinal lining into your bloodstream. Your blood carries simple sugars, amino acids, glycerol, and some vitamins and salts to the liver. Your liver stores, processes, and delivers nutrients to the rest of your body when needed. The lymph system , a network of vessels that carry white blood cells and a fluid called lymph throughout your body to fight infection, absorbs fatty acids and vitamins.

Your body uses sugars, amino acids, fatty acids, and glycerol to build substances you need for energy, growth, and cell repair. Your hormones and nerves work together to help control the digestive process. Signals flow within your GI tract and back and forth from your GI tract to your brain. Cells lining your stomach and small intestine make and release hormones that control how your digestive system works.

These hormones tell your body when to make digestive juices and send signals to your brain that you are hungry or full.

Your pancreas also makes hormones that are important to digestion. You have nerves that connect your central nervous system—your brain and spinal cord—to your digestive system and control some digestive functions. For example, when you see or smell food, your brain sends a signal that causes your salivary glands to "make your mouth water" to prepare you to eat.

When food stretches the walls of your GI tract, the nerves of your ENS release many different substances that speed up or delay the movement of food and the production of digestive juices. The nerves send signals to control the actions of your gut muscles to contract and relax to push food through your intestines. Griffin P. Rodgers explaining the importance of participating in clinical trials.

Clinical trials that are currently open and are recruiting can be viewed at www. The NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Why is digestion important? What Is the Large Intestine? The large intestine is made up of the following parts: Cecum: This first section of your large intestine looks like a pouch, about two inches long.

It takes in digested liquid from the ileum and passes it on to the colon. Colon: This is the major section of the large intestine; you may have heard people talk about the colon on its own. The colon is also the principal place for water reabsorption, and absorbs salts when needed. The colon consists of four parts: Ascending colon: Using muscle contractions, this part of the colon pushes any undigested debris up from the cecum to a location just under the right lower end of the liver.

Transverse colon: Food moves through this second portion of the colon, across your front or anterior abdominal wall, traveling from left to right just under your stomach. Descending colon: The third portion of colon pushes its contents from just near the spleen , down to the lower left side of your abdomen.

Sigmoid colon: The final S-shaped length of the colon, curves inward among the coils of your small intestine, then empties into the rectum. Rectum: The final section of digestive tract measures from 1 to 1. Leftover waste collects there, expanding the rectum, until you go to the bathroom. At that time, it is ready to be emptied through your anus.

Fax: Emergency referrals are accepted 24 hours a day at Find a Doctor. Contact Us. Pay My Bill. Gender Male Female. Pittsburgh, PA Get directions to our main campus. The liver , gallbladder , and pancreas are accessory organs of the digestive system that are closely associated with the small intestine. The small intestine is divided into the duodenum , jejunum , and ileum. The small intestine follows the general structure of the digestive tract in that the wall has a mucosa with simple columnar epithelium , submucosa , smooth muscle with inner circular and outer longitudinal layers, and serosa.

The absorptive surface area of the small intestine is increased by plicae circulares , villi, and microvilli. Exocrine cells in the mucosa of the small intestine secrete mucus , peptidase, sucrase, maltase, lactase, lipase, and enterokinase.

Endocrine cells secrete cholecystokinin and secretin. The most important factor for regulating secretions in the small intestine is the presence of chyme. This is largely a local reflex action in response to chemical and mechanical irritation from the chyme and in response to distention of the intestinal wall. The large, hollow organs of the digestive system contain muscle that enables their walls to move.

The movement of organ walls can propel food and liquid and can mix the contents within each organ. Typical movement of the esophagus, stomach, and intestine is called peristalsis. The action of peristalsis looks like an ocean wave moving through the muscle. The muscle of the organ produces a narrowing and then propels the narrowed portion slowly down the length of the organ.

These waves of narrowing push the food and fluid in front of them through each hollow organ. The first major muscle movement occurs when food or liquid is swallowed. Although we are able to start swallowing by choice, once the swallow begins, it becomes involuntary and proceeds under the control of the nerves.

The esophagus is the organ into which the swallowed food is pushed. It connects the throat above with the stomach below. At the junction of the esophagus and stomach, there is a ringlike valve closing the passage between the two organs. However, as the food approaches the closed ring, the surrounding muscles relax and allow the food to pass. The food then enters the stomach, which has three mechanical tasks to do.

First, the stomach must store the swallowed food and liquid. This requires the muscle of the upper part of the stomach to relax and accept large volumes of swallowed material. The second job is to mix up the food, liquid, and digestive juice produced by the stomach.

The lower part of the stomach mixes these materials by its muscle action. The mixture is referred to as chyme. Several factors affect emptying of the stomach, including the nature of the food mainly its fat and protein content and the degree of muscle action of the emptying stomach and the next organ to receive the contents the small intestine.

As the food is digested in the small intestine and dissolved into the juices from the pancreas, liver, and intestine, the contents of the intestine are mixed and pushed forward to allow further digestion.

Finally, all of the digested nutrients are absorbed through the intestinal walls. The waste products of this process include undigested parts of the food, known as fiber, and older cells that have been shed from the mucosa.

These materials are propelled into the colon, where they remain, usually for a day or two, until the feces are expelled by a bowel movement. The small intestine has 3 segments:. Duodenum — The chyme first enters into the duodenum where it is exposed to secretions that aid digestion.

The secretions include bile salts, enzymes, and bicarbonate. Pancreatic enzymes help digest carbohydrates and fats. Bicarbonate from the pancreas neutralizes the acid from the stomach. Jejunum — The chyme is then further transited down into the second or middle part of the small intestine, the jejunum. Ileum — The ileum is the last section of the small intestine and leads to the large intestine or colon.

The ileum mainly absorbs water, bile salts, and vitamin B The ileocecal valve is a one-way valve located between the ileum and the cecum, which is the first portion of the colon. This valve helps control the passage of contents into the colon and increases the contact time of nutrients and electrolytes essential minerals with the small intestine.

It also prevents back-flow reflux from the colon up into the ileum, and helps minimize the movement of bacteria from the large intestine up into the small bowel. The primary function of the large intestine or colon is to absorb fluids and electrolytes, particularly sodium and potassium, and to convert remaining luminal contents into more solid stool.

The colon absorbs on average 1—1. Another function of the colon is to break down ferment dietary fiber to produce short chain fatty acids — substances that can be absorbed and provide added nutrition. The first portion of the colon, the cecum, is shaped like a pouch, and is the area of storage for the contents arriving from the ileum.

The second portion is the ascending colon, where fluids are absorbed and where some stool formation begins. The glands that act first are in the mouth — the salivary glands. Saliva produced by these glands contains an enzyme that begins to digest the starch from food into smaller molecules.

The next set of digestive glands is in the stomach lining.