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Small intestine digestion


At the small intestine, most digestion of nutrients occurs as well as absorption, ie assimilation of nutrients.

At the duodenum, the secretions of the liver and pancreas are released. In this first portion of the small intestine, chemical digestion is performed mainly - with the joint action of bile, pancreatic juice and enteric or intestinal juice acting on the chymus.

In chemical digestion, there is the action of these secretions:

  • Bile - Liver secretion stores in the gallbladder. It is released into the duodenum through a canal and contains no digestive enzymes; but bile salts separate the fats into microscopic particles, working similar to a detergent. This facilitates the action of pancreatic enzymes on lipids.
  • Pancreatic Juice - It is produced by the pancreas. It has several enzymes that act on the digestion of proteins, carbohydrates and lipids.
  • Enteric Juice - is produced by the intestinal mucosa. It has enzymes that act in the transformation, among other substances, of proteins and carbohydrates.

At the end of the digestive process in the small intestine, the resulting set of substances forms a viscous white liquid called kilo.

Digestion continues in the jejunum and ileum.

The fate of food

O kilo, a product of digestion, is composed of nutrients transformed into very small molecules, plus vitamins and minerals. The substances that make up the kilo can be absorbed by the body, that is, they pass through the cells of the intestine through the small intestine villi.

This causes the passage of nutritive substances to the blood capillaries - the absorption of nutrients occurs. What is not absorbed, some of the water and food mass, made up mainly of fiber, passes into the large intestine.

Large intestine

After digestion in the small intestine, what remains of the kilo reaches the large intestine. It absorbs the water and minerals still present in food waste and then takes them into the bloodstream.

Some intestinal bacteria ferment and thus break down food waste and produce vitamins (the vitamin K and some B) vitamins that are used by the body. In these activities, bacteria produce gases - some of them are absorbed through the intestinal walls and some are eliminated by the anus.

The undigested material, the fibersFor example, it forms stools that accumulate in the rectum and subsequently pushed by muscle or peristaltic movements out of the anus. That's when we feel like defecating, that is, eliminating the stool.

After all the digestion steps are completed, the nutrients that reach the bloodstream are distributed to all cells and thus used by the body.

The food way

The table below is for fixing the digestion steps. Take a close look at it and try to identify, and each of its elements, the learned stages of digestion.

Digestive Enzyme Place of production Target Substance Action
ptaline salivary glands starch

Decomposes starch into maltoses

pepsin stomach proteins Break down proteins into smaller fragments
sucrase small intestine sucrose It breaks down sucrose into glucose and fructose.
lactase small intestine lactose

Decomposes lactose into glucose and galactose.

lipase pancreas lipids Lipid breakdowns in fatty acids and glycerols.
trypsin pancreas proteins Break down proteins into smaller fragments
pancreatic amylase pancreas starch Decomposes starch into maltoses
maltase small intestine maltoses Decomposes Maltose into Free Glucose
peptidase small intestine protein fragments Decomposes protein fragments into amino acids.