SMALL INTESTINE

Tube (6 or 7 m) located between the pylorus and the ILEOCECAL VALVE, where the large intestine begins.

Sections :

- DUODENUM (25CM, shaped like a horseshoe) - JEJUNUM (middle section, longest part) - ILEUM (final section that ends int the large intestine)

After the pylorus opens, the chyme enters the small intestine.

Once in the duodenum, chyme mixes with secretions released there from two organs: LIVER AND PANCREAS

PANCREAS

Glandular organ located in the abdomen behind the stomach, with 2 functions :

- produces INSULIN AND GLUCAGON (hormones) that regulates the quantities of glucose in blood.

- secrete PANCREATIC JUICES release through the AMPULLA OF VATER (liver ducts also join there) Pancreatic juices contains ENZYMES that digest carbohydrates, fats and proteins, and SODIUM BICARBONATE that neutralises chyme´s acidity protecting the intestinal cells.

LIVER

Organ located in the right upper part of the abdomen that performs functions related to digestive and excretory processes (captures and destroys most toxic molecules that enter the body , alcohol, drugs ...)

Liver produces BILE, released into the duodenum through the Ampulla of Vater.

This bile, as the pancreatic juices, is not secreted continuosly, but it is stored in the gallbladder, and it is only released when food enters the duodenum.

Bile DOES NOT CONTAIN ENZYMES. It contains BILE SALTS, that intervene in the emulsification of fats, transforming them into small drops, that help enzymes from pancreatic and intestinal juices to break them down.

In the small intestine, apart from bile and pancreatic juices, the small intestine´s mucous glands secrete INTESTINAL JUICES, similar to pancreatic juices, that contain enzymes capable of digesting all types of molecules.

There the chyme is transformed in CHYLE.

FOOD ------> BOLUS --------------> CHYME -------------------> CHYLE

SALIVA GASTRIC J. PANCREATIC J. BILE INTESTINAL J.

FOOD ABSORPTION

Passage of nutrients to our blood , so they can be distributed across the organism.

They go through the small intestine´s mucosa (villi and microvilli), entering the blood capillaries, except the fat digestion products that are absorved by the lymphatic capillaries.

FOOD TO NUTRIENTS

STARCH ---------------------------------------------------> MALTOSE -----------------------------> GLUCOSE AMYLASE (saliva, pancreatic j., intestinal j.) MALTASE (intestinal j.)

SUCROSE ------------------------------> FRUCTOSE AND GLUCOSE SUCRASE (intestinal j.)

FATS -------------------------------------------------> GLYCERINE AND FATTY ACIDS LIPASE (intestinal and pancreatic j.)

PROTEINS ---------------------> PEPTIDE -------------------------> SHORT PEPTIDE -----------------> AMINOACIDS PEPSIN (gastric j.) TRYPSIN (pancreatic j.) EREPSIN (intestinal j.)

These nutrients must be distributed to the tissues when cell will use them to obtain energy or make new molecules.

	Created by gerardo morezuelas almost 4 years ago

3º de ESO Biología y Geología (3- NUTRITION : digestive and respiratory system) Slide Set on 2- DIGESTIVE SYSTEM, created by gerardo morezuelas on 28/12/2020.