Nutrition Chap #3

Digestion

Breakdown of food substances into simpler forms that can be absorbed and used Absorbtion of nutrients

Metabolism

Breaking down nutrients for energy

Gallbladder (Accessory Organ)

A sack attached to the liver where bile is stored and concentrated. Bile empties from the gallbladder into the common bile duct. When chyme with fatty contents enters the small intestine, a hormone stimulates the gallbladder to contract and empty bile into the small intestine.

Exocrine

A secretion that is expelled through a duct into a body cavity or onto the surface of the skin.

Endocrine

A term to describe a gland secreting or a hormone being secreted into the blood.

Small Intestine

ABSORPTION TAKES PLACE IN THE SAMLL INTESTINE Chyme must touch the walls to make contact with secretions and be absorbed at the proper places. Peristalsis moves chyme through the small intestine. Stimulated by fiber Slowed by fat The ileocecal valve controls the flow of contents going into the large intestine. The small intestine works to break down food and nutrients to their smallest absorbable components. This breakdown is complex, requiring many chemical reactions: Hormonal messages tell the gallbladder to send its emulsifier, bile. Hormones send messages to the pancreas to release the neutralizer, bicarbonate. Pancreatic and intestinal enzymes act to break bonds of larger nutrients.

Liver (Accessory Organ)

All nutrients go to the live and decide where those nutrients are going to go Determines the metabolic fate of every nutrient we digest and absorb. Performs a wide variety of functions which are essential for life. Produces bile which helps to emulsify fat and improve the efficiency of fat digestion.

Digestive System

Composed of the alimentary canal and accessory structures. Mouth, esophagus, stomach, small intestine (duodenum, jejunum, and ileum), large intestine (colon), and anus.

Mouth

Digestion begins in the mouth where food is broke down so it is able to fit down the esophagus

Pancreas (Accessory Organ)

Endocrine functions include: Secretion of the hormones insulin and glucagon which regulate blood glucose levels. Exocrine functions include: Secretion of digestive enzymes which act on carbohydrates, proteins, fats and bicarbonate. These are secreted into the duodenum.

Villi

Fingerlike projections of the sheet of cells that line the GI tract; the villi make the surface area much greater than it would otherwise be Vitamins absorb here go to the liver and then to lymph

Microvilli

Tiny hairlike projections on each cell of the intestinal tract lining that can trap nutrient particles and translocate them into the cells

Sphincters

rings of muscles, controls the openings into and leading out of the stomach

Stomach

Stores food until it can be processed. Forms chyme: the semi-liquid blend of food and gastric secretions that forms in the stomach during digestion. Controls movement of chyme into the small intestine at a rate suitable for digestion and absorption by the small intestine.

Emulsifier

A compound with both water-soluble and fat-soluble portions that can attract lipids into water to form an emulsion.

Bile

A compound made from cholesterol by the liver, stored in the gallbladder, and secreted into the small intestine. It emulsifies lipids to ready them for enzymatic digestion. It is made in the live and stored in the gallbladder

Accessory Organs

Liver Gallbladder Pancreas

Esophagus

No digestion takes place in the esophagus. Food passes from the mouth to the stomach and travels through the esophagus. Sphincters open and close to allow the bolus to pass. Sphincter: a circular band of muscle fibers that constrict a passage or close a natural opening in the body. Peristalsis: Longitudinal and circular muscle layers of the esophagus rhythmically push the bolus down the esophagus. Food passes from the mouth to the stomach through the esophagus