How does egestion occur

It has been estimated that there are over species of bacteria present in the large intestine, and these friendly commensal bacteria perform a variety of functions. For example, undigested carbohydrates fibre are metabolised to short-chain fatty acids, and small amounts of vitamins, especially vitamin K and the vitamin B group, are produced for absorption into the blood. As undigested material accumulates in the rectum, it stimulates a response that leads to the evacuation of the waste through the anus.

Add to collection. Go to full glossary Add 0 items to collection. Download 0 items. Twitter Pinterest Facebook Instagram. Email Us. See our newsletters here. Feces contain indigestible food and gut bacteria almost 50 percent of content. It is stored in the rectum until it is expelled through the anus via defecation. Digestion involves two processes - physical and chemical.

During the physical process, the food is mixed and moved throughout the gastrointestinal tract. This process is also referred to as motility and the partially digested food is propelled by the wave-like action called peristalsis. Ring-like muscular valves called sphincters prevent the back flow of partially digested food and digestive juices.

There are sphincters between the esophagus and stomach esophageal sphincter , between the stomach and small intestine pyloric sphincter and small intestine and colon ileocecal sphincter. The chemical process of digestion involves the release of water, acid, bicarbonate and enzymes to be mixed with the food to further break it down into smaller subunits.

Chemical breakdown starts in the mouth where enzymes break down complex carbohydrate. In the stomach, water and acid are released to begin the breakdown of protein. A mucus lining protects the stomach from the corrosive acid. The mixture, also known as chyme, enters the small intestine where bicarbonate is introduced to neutralize the acid and enzymes are added to break chemical bonds.

Most small intestine digestive enzymes are produced in the pancreas and small intestine. Our nervous system and hormones control digestion. The nervous system consists of the central nervous system, and the peripheral nervous system.

Our brain and spinal cord make up the central nervous system while the peripheral system lies outside the skull and vertebral column. There are two components to the peripheral system: the somatic system that supplies the skin and muscle, and the autonomic system which supplies smooth muscle, cardiac muscle, and glands. The PSNS supplies signals to maintain normal function and conserve body processes.

The SNS provides signals to accelerate the process. Our gastrointestinal tract receives signals from the central and autonomic systems as well as sends signals to these systems. Hormones are also involved in regulating digestion. Your digestive tract secretes hormones to control the release of digestive enzymes and juices. Here is a table of some hormones. Our appetite and hunger are controlled by a complex process that involves many signals.

Here is a brief overview of that process. Decide whether you want to consume pre- and probiotic foods to benefit your health. Visit the websites below to help in your decision-making process. Defend your decision scientifically. Skills to Develop Sketch and label the major organs of the digestive system and state their functions.

From the Mouth to the Stomach There are four steps in the digestion process Figure 2. From the Stomach to the Small Intestine When food enters the stomach, a highly muscular organ, powerful peristaltic contractions help mash, pulverize, and churn food into chyme.

The stomach has three basic tasks: To store food To mechanically and chemically break down food To empty partially broken-down food into the small intestine The length of time food spends in the stomach varies by the macronutrient composition of the meal. Video 2. There it mixes with bile and pancreatic juices that further break down nutrients.

Finger-like projections called villi line the interior wall of the small intestine and absorb most of the nutrients. The remaining chyme and water pass to the large intestine, which completes absorption and eliminates waste. Villi that line the walls of the small intestine absorb nutrients into capillaries of the circulatory system and lacteals of the lymphatic system.

Villi contain capillary beds, as well as lymphatic vessels called lacteals. Fatty acids absorbed from broken-down chyme pass into the lacteals.

Other absorbed nutrients enter the bloodstream through the capillary beds and are taken directly to the liver, via the hepatic vein, for processing.

Chyme passes from the small intestine through the ileocecal valve and into the cecum of the large intestine. Any remaining nutrients and some water are absorbed as peristaltic waves move the chyme into the ascending and transverse colons.

The digestive tract, also called the alimentary canal or gastrointestinal GI tract , consists of a long continuous tube that extends from the mouth to the anus. It includes the mouth, pharynx , esophagus , stomach , small intestine , and large intestine.

The tongue and teeth are accessory structures located in the mouth. The salivary glands, liver , gallbladder , and pancreas are major accessory organs that have a role in digestion. These organs secrete fluids into the digestive tract.

Digestion and absorption occur in the digestive tract.