COMPONENTS OF THE DIGESTIVE SYSTEM
I. Digestive tube
1. the oral cavity includes:
- the tongue, muscular organ with role in speech, mastication, swallowing and taste sensitivity
- teeth, hard organs with a role in mastication and speech
2. the pharynx is a place of crossing the digestive and respiratory pathways
3. the esophagus, located posterior to the trachea and plays a role in swallowing
4. the stomach is a cavitary organ; it communicates with the esophagus through the cardiac orifice and the duodenum through the orifice of the pylorus;
5. the small intestine has three segments (duodenum, jejunum and ileum)
6. large intestine, made up of: cheque, colon and rectum;
II. Annex glands
1. Salivary glands are located in the vicinity of the oral cavity.
2. Liver, has an exocrine secretion, bile.
3. The pancreas (mixed gland) secretes pancreatic juice, which is eliminated in the duodenum.
Enzyme categories:
- glycolytic or amylolytic enzymes: convert carbohydrates into monosaccharides, glucose, fructose, galactose
- lipolytic enzymes: convert lipids into glycerin and fatty acids
- proteolytic enzymes: convert proteins into amino acids
PHYSICAL-CHEMICAL TRANSFORMATIONS OF FOOD IN THE DIGESTIVE TUBE
Digestion is the totality of the mechanical, physical, and biochemical changes that food undergoes in the digestive tract, as a result of which complex organic substances become simple, soluble, absorbable organic substances called nutrients.
Mechanical transformations: mastication, trituration, deglution
Physical transformations: softening of food, dissolving water-soluble substances, emulsifying fats
Chemical transformations: complex food substances become substratesimplificative enzyme subaction
Digestive enzymes are components of digestive juices that act only on certain organic food substances. Some enzymes are secreted in inactive form and become active in the presence of certain substances.
THE STOMACH
Intestinal absorption is the process by which the final products of digestion, along with a large amount of H20, mineral ions and vitamins, pass through the lining of the small intestine, passing into the blood and lymph.
Absorption of certain constituents can be achieved:
- in the stomach (H20, chlorides, alcohols, carbon dioxide)
- in the colon (H20 and electrolytes).
Physiology of the large intestine
The last segment of the digestive tube (large intestine) consists of:
a) cecum
b) colon ascending, transverse, descending and sigmoid
c) rectum (this continues with the anal canal that opens through the anal orifice)
Undigested debris and unabsorbed products pass further into the large intestine.Here are carried out secretory, motor and absorption activities, processes of fermentation and putrefaction.After them, fecal matter is formed that is eliminated to the outside of the body by the act called defecation.
THE LARGE INTESTINE
Bile has a special action, it does not contain enzymes, but bile salts, substances similar to detergents, decreasing lipid drops. Bile salts are also antibacterial. Bile also contains unhelpful substances, which are eliminated by feces.
Intestinal juice and pancreatic juice contain enzymes for carbohydrates, proteins and lipids, leading to the formation of nutrients (nutrients). Nutrients (glucose, fatty acids, amino acids, etc.), vitamins, minerals and water are absorbed (active and passive) in the blood and lymph (liquid that circulates through special vessels). Absorption and blood transport ensure the nourishment of the entire body, up to all cells.
THE ORAL DIGESTION
The oral digestion consists of all mechanical, physical and chemical transformations, suffered by food in the oral cavity.The short time spent by food in the oral cavity is sufficient for their processing by mastication, mastication, impregnation with saliva and the action of the enzyme in saliva.
THE GASTRIC DIGESTION
Gastric digestion consists of the total transformation suffered by food in the stomach; it is the result of the secretory and motor activity of the stomach.
THE ORAL CAVITY
