Where are the main parts of food digestion and absorption? Why

The main site of food digestion and absorption is in the small intestine. There are capillaries and capillary lymphatic vessels in the villi of the small intestine, and the villus wall, capillary wall, and capillary lymphatic wall are all composed of a layer of epithelial cells, which is conducive to the absorption of nutrients.

The stomach is the most distended part of the digestive tract, and its function is to temporarily store food and perform the initial digestion of proteins. The large intestine is the site of feces formation, which can absorb small amounts of water and inorganic salts.

and vitamins; The rest of the digestive tract is largely non-absorbent.

Chyme enters the small intestine from the stomach and begins digestion in the small intestine due to pancreatic juice, small intestinal fluid and bile.

The chemical digestion and the mechanical digestion of the small intestine movement, the digestion process of food is basically completed in the small intestine, and most of the digested nutrients are also absorbed in the small intestine, so the small intestine is the most important part of digestion and absorption.

Small intestine, 1 large absorption area. The human small intestine is 5 7 m long, and its mucosa has annular folds, with a large number of villi on the folds, and microvilli on the intestinal villi, which finally makes the absorption area of the small intestine reach about 200.

2. The food stays in the small intestine for a long time, generally 3 8 hours.

3. Food has been digested into small molecules that can be absorbed in the small intestine.

4. There are abundant capillaries and capillary lymphatic vessels in the villi of the small intestine, which provide a good way for absorption.

The stomach digests food and can also be stored, and the gastric cavity capacity is only 50ml, but it can hold 1000ml in diastole

Upper Gastrointestinal Master Digestion!

Such as the stomach,! Lower Gastrointestinal Master Absorption!

Such as small intestine 1

The spleen and stomach are digested and functioning! Gastrointestinal absorption.

Answer]: The small intestine is the main organ for digesting and transporting food and absorbing nutrients, and digestion in the small intestine is the main stage of the whole digestive process. The function of the stomach is to temporarily store food and carry out the initial digestion of the epidermal pesten.

The main function of the large intestine is to absorb water and salts and provide a temporary storage site for digested food debris.

The digestion and absorption of food is mainly done in the small intestine.

The main sites of food absorption are the duodenum and jejunum in the upper part of the small intestine. The ileum is primarily a reserve of absorption function for compensatory needs, while the large intestine is primarily responsible for absorbing water and salts.

The lining of the small intestine is covered with annular folds, villi, and microvilli. Through the amplification of these annular folds, villi and microvilli, the absorption area of the girder of the small intestine curve can reach 200 m2. Moreover, this structure of the small intestine makes its inner diameter thinner, which increases the friction of chyme flow, prolongs the residence time of food in the small intestine, and creates favorable conditions for the absorption of food in the small intestine.

The active transport of nutrients requires the assistance of a carrier on the cell. A carrier is a lipoprotein that transports nutrients in and out of cell membranes. When the complex transports human epithelial cells through the cell membrane, the nutrients are separated from the carrier and released into the human cell, and the carrier is transferred back to the outer surface of the cell membrane.

Food is not absorbed before entering the stomach, the stomach can only absorb a small amount of water and alcohol, the large intestine mainly absorbs water and electrolytes that are not fully absorbed in the small intestine, and the absorption of nutrients mimicking travel is mainly carried out in the small intestine.

The characteristics of active transshipment are:

When transporting nutrients, the carrier needs to be catalyzed by enzymes and provide energy for burial, and the energy comes from the decomposition of adenosine triphosphate; This transport system can be saturated and the maximum transport volume can be suppressed; Vector systems are specific, i.e., there are several different carrier systems on the cell membrane, each carrying only certain nutrients.

After food is digested, macromolecular substances become small molecules, in which proteins become amino acids, polysaccharides are decomposed into simple sugars, fats are decomposed into fatty acids, glycerol, etc., and vitamins and minerals are released from the cells of food during digestion. The process by which these nutrients pass through the walls of the digestive tract into the bloodstream is called "absorption".

1. Oral cavity, food is ground after chewing in the mouth, the food is mechanically digested, and the food is preliminarily decomposed into maltose by salivary enzyme in the oral cavity (this is the reason why the white steamed bun is sweeter the more you chew), and the food is broken and mixed with saliva to form a food ball, which is easy to swallow. The oral digestion time is very short, generally 15-20 seconds.

2. Esophagus, the esophagus is the intermediate passage between the oral cavity and the cardia, and food enters the stomach through the peristalsis of the esophagus.

3. Stomach (1-4 hours), the movement of the stomach is realized by the smooth muscle relaxation of the stomach wall, and the stomach has the function of endocrine and holding food, secreting gastric juice, and initially digesting food. The stomach mechanically digests food through movement. The movement of the stomach causes gastric juice to mix well with food and further grind the lumpy food, which is conducive to chemical digestion.

Peprate paraben enzyme breaks down protein to produce peptone and a small amount of polypeptides and amino acids to complete the chemical digestion of food. Hence the role of the stomach in the initial digestion of food. And through the emptying of the stomach, the food enters the ten buried mold bindenum from the stomach.