Digestive system: Functions

We will discuss:
General structure of the digestive
Digestion in the mouth
Digestion in stomach
Digestion in the small intestine
Absorption and Metabolism

The body be taken from outside a series of materials (food) to develop and maintain their structures and as an energy source that makes possible their activities. These materials must be processed to be usable. This empties the digestive secretion products to hydrolyze and convert food into smaller molecules can pass through the digestive tract, joining circulating fluids (blood and lymph) and distributed throughout the body.

General structure of the digestive

The gastrointestinal tract is a long tube of various calibres, widened in parts and consists of two layers: a glandular and other muscles. The various parties that form it are: mouth, pharynx, esophagus, stomach (fundus, corpus of the stomach and pylorus), small intestine (duodenum, jejunum and ileum) and large intestine (cecum, colon and rectum).

Digestion in the mouth

In the mouth begins enzymatic breakdown of food substances. Because saliva contains various ions, mucin and ptyalin, partially hydrolyzed starch, breaking it down (over 50%) in a mixture of dextrins and maltose. This enzyme action takes place at a pH around neutral. The man segregated from one to two liters of saliva a day. The mere presence of food in the mouth triggers a copious flow of saliva. It is a reflex phenomenon. There are three salivary glands: the sublingual and the submandibular gland.

Digestion in stomach
In the stomach the food experience strong contractions that allow the mixture thereof with the gastric juice. Millions of tubular glands are lodged in the mucous layer and flow into the gastric cavity through so many visible holes. The cells that form these glands produce mucus, pepsinogen and hydrochloric acid.

The gastric juice is a mixture of individual secretions of all cells considered, plus the mucosal epithelium itself. It is a watery fluid containing mucin, hydrochloric acid, pepsinogen and renin as most important products. The pepsinogen is converted to pepsin through the CHL. Pepsin hydrolyzes proteins, making them simpler peptides. You need a strongly acidic pH for pepsin action. This is provided by the HLC. Hydrochloric acid is also used as a solvent, hydrolyzing substances and antiseptic, it prevents the putrefaction of the stomach contents. Against the acidity of gastric juice and pepsin, mucin acts as a backstop. Renin converts or rennet milk protein casein, insoluble protein, it is then digested by pepsin and other proteolytic enzymes.

Digestion in the small intestine

Between the villi are the crypts of Lieberkiihn, glands that secrete the enteric juice. Enteric juice is alkaline and contains a large amount of mucus. Enzymes are considered as characteristic of this juice: the enterokinase converts trypsinogen to trypsin, various peptidases, lipase that hydrolyzes fats and likewise an amylase which breaks down starch.

Pancreatic juice, secreted by pancreatic acinar cells of the duodenum is alkaline and rich in sodium bicarbonate, and contains as major enzymes: trypsin, for proteins, lipase, breaks down fats into fatty acids and glycerin amylase partially hydrolyzed starch; maltase, sucrase and lactase that break down disaccharides into monosaccharides for.

Bile is the exocrine secretion of liver cells. They play an important role in the digestion of fats. The large intestine lacks enzymatic activity. The basic function of thickness is the absorption of water, thereby adjusting the consistency of stools.

Absorption and Metabolism

The end products of digestion are monosaccharides, amino acids and fatty acids. The small intestine is the place where they made the most important processes of absorption through the intestinal villi million. In these there is a blood vascular network and a lymphatic vessel.

To produce the absorption process involved in the differences in concentration of each substance, the hydrostatic pressure, oncotic pressure, the membrane permeability and chemical affinities between compounds.

In the absorption of minerals involves many factors such as vitamins. Glucose and amino acids are absorbed by the blood capillaries and carried through the portal vein to the liver and then into the general circulation. The fatty acids pass into the lymphatics of the villi and finally into the venous system.

It is called the set of energy metabolism that requires the individual to function. Even at complete rest, the body uses energy to maintain its temperature, getting the heart and respiratory muscles, etc.. The minimum metabolic activity called metabolism.

Related Topics

* Urinary
* Locomotor
* Respiratory
* Sensory apparatus
* Circulatory System
* Nervous System
* Digestive Enzymes: Roles

*Automatic Translation