Main function of the digestive system

Written by patricia e. bardowell
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Main function of the digestive system
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The digestive process begins when food is ingested. The time line for this process is between 24 - 72 hours, for a healthy adult, but this is based on the individual, and the type of food eaten. Fibre for example, is high in roughage, and speeds up the digestion process. The food is mixed with chemicals, and digestive substances, producing energy to the body, and eliminating waste.

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Overview

The digestive process begins when food is ingested. The time line for this process is between 24 - 72 hours, for a healthy adult, but this is based on the individual, and the type of food eaten. Fibre for example, is high in roughage, and speeds up the digestion process. The food is mixed with chemicals, and digestive substances, producing energy to the body, and eliminating waste.

The Digestive System

The digestive system consists of the mouth, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, and a large intestine.

Main Function

The main function is the breakdown of food into smaller portions, to be absorbed as nutrients into the bloodstream, and transferred to the cells to produce energy, and aid in the elimination process.

Mouth

When food enters the mouth, the salivary gland releases saliva containing enzymes. The jaw and teeth, breakdown the food into smaller pieces, and when swallowed, moves into the oesophagus.

Oesophagus

By a wave of muscle contractions (peristalsis), the food in the oesophagus is pushed into the stomach. The esophageal sphincter (LES) closes to prevent re-entry. If rejected by the stomach, the esophageal sphincter, reopen, by contractions, and force the food back into the mouth, as vomit.

Stomach

Food passes through four phases. Chemical digestive juices and enzymes mix with the food, and is dissolved and absorbed in the blood. The food is squeezed by stomach muscles, and liquefied by the juices.

The Liver

The liver has several functions, the main one is the processing of fat, and liquefied food rich in nutrients, which is drained from the small intestines to make it useful. It also produces sugars from protein, and fatty substances, releasing albumin and keeping the blood vessels hydrated with fluids. Toxins in the blood is converted, and excreted safely from the body, and calcium used to reduce acid in the waste.

Gall Bladder

Bile is released from the liver into the gall bladder, and later released into the small intestine, to dissolve fats.

The Pancreas

The pancreatic duct delivers digestive juices into the small intestine.

The Small Intestine

It has three sections, duodenum, jejunum, and ileum. The duodenum and stomach meets at the pyloric sphincter preventing material from going back into the stomach. The duodenum breaks down carbohydrate into sugar, with the use of enzymes from the pancreas, and liver. Lipase from the pancreas breaks down fats in the duodenum to produce fatty acids.
The jejunum absorbs carbohydrates and protein from the material. Pepsin and amino acids breaks down protein in the stomach. The ileum absorb fats, and bile salts, vitamins B12, vitamins in fatty liquids, electrolytes, bile salts, and water through its pores into the blood. The ileocecal valve, which joins the ileum and large intestines together prevents the backward flow of the pasty material into the small intestine.

Large Intestine and The Rectum

The large intestine (colon) collects undigested food. It moves waste from the small intestine to rectum, passing through the ascending colon, and transverse colon, and absorbing water through this process. The waste becomes firm when it reaches the sigmoid colon, and is designed to slow down the elimination of the waste, until it is ready. The rectum stores the waste, and uses the anal sphincter to prevent release of the waste, until ready.

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