Digestive Hormones & Important Secretions

pepsinogen

(Stomach) -inactive protein-digesting enzyme

Gastrin (Hormone)

-Released by stomach and duodenum in response to food reaching the stomach. -Function: Triggers the stomach to release HCl and pepsinogen; stimulates gastric & intestinal motility(flow and go).

pancreatic juice

-alkaline mixture of sodium bicarbonate and enzymes. -sodium bicarbonate neutralizes the acidic chyme arriving from the stomach, protecting the small intestine from acid damage. -amylase (starch), pancreatic lipase (fat), several proteases (proteins) - break large macronutrients molecules into smaller subunits.

Catalysis

-brings certain molecules close together and then creates a favorable environment for the chemical reactions known as hydrolysis reaction.

Lingual Lipase

-fat producing fat-digesting enzyme that is produced mainly during infancy.

chyme

-mixing transforms solid foods into chyme a soupy acid mixture. -only 1 tsp of chyme is released at a time into small intestine.

Intrinsic factor (IF)

-produced in the stomach is required for absorption of vitamin B12 in the small intestine.

Digestive Enzymes

-protein molecules that speed up digestion by catalyzing chemical reactions.

Gastric inhibitory peptide (Hormone)

-released by small intestine as digestion progresses. -Function: signals the stomach to limit release of gastric juices and SLOWS gastric motility. -helps slow release of chyme into SI - giving small intestine time to digest nutrients.

Secretin (Hormone)

-released by small intestine in response to acidic chyme. -stimulates release of pancreatic bicarbonate- neutralize too acidic.

Cholecystokinin (CCK) (Hormone)

-released by small intestine in response to presence of dietary fat in chyme. -Function: stimulates release of pancreatic enzymes and release of bile from the gallbladder. (break down & emulsify)

Bile

-site of production: Liver (stored in gallbladder) -function: aids in fat digestion (emulsifies fat)

Saliva

-site of production: mouth -function: contributes to starch digestion, lubrication, and swallowing.

Mucus

-site of production: mouth, stomach, small and large intestines. -Function: protects GI tract cells, lubricates digesting food. -protects stomach from HCl and pepsin -relies on presence of hormone like compounds called prostaglandins.

Enzymes (amylases, lipases, proteases)

-site of production: mouth, stomach, small and large intestines. -function: promotes digestion of carbohydrates, fats, and protein into forms small enough for absorption.

Bicarbonate

-site of production: pancreas, small intestine -function: neutralizes stomach acid when it reaches the small intestine.

Acid (HCl)

-site of production: stomach -function: promotes digestion of protein, destroys microorganisms, increases solubility of minerals. -dissolves dietary minerals (calcium) -converts pepsinogen into active protein-digesting enzyme pepsin.

Hormones

-site of production: stomach, small intestine -function: regulates digestion and absorption

lysosyme & amylase

-to kill bacteria -to break down starch (only 5%)

Hydrolysis Reaction

-water breaks apart molecule that are too large to pass through the GI tract wall. -eventually yield simple molecules that are small enough to be absorbed through the intestinal wall.

Hormones

chemical messenger produced in one tissue that subsequently acts on cells or tissues in another part of the body.

bolus

food after grinded in mouth

Peristaisis

process of the food mixed with digestive secretions propelling down the GI tract. - The process begins in the esophagus as 2 waves of muscle actions and ends in the elimination of waste through the rectum.