DS Part 4: Small Intestine, Pancreas, Gallbladder, Liver

Duodenal Glands

protects small intestine by neutralizing chyme

secretes:

• neutral & alkaline glycoproteins

• bicarbonate ions

Intestinal Glands

completes process started by pancreatic juice

secretes:

• intestinal juice

absorptive cell

digests & absorbs nutrients

goblet cell

secretes mucus

enteroendocrine cell

secretes:

• secretin

• cholecystokinin

• GIP

Paneth cell

secretes lysozyme

• capable of phagocytosis

Pancreas Secretion

pancreatic juice

2 types of pancreatic juice

Endocrine Pancreatic Secretion

• secretes hormones (insulin, glucagon, etc.)

Exocrine Pancreatic Secretion

• secretes enzymes for digestion; by exocrine acini

Composition of Pancreatic Juice

• trypsin

• pancreatic amylase (digest carbs)

• pancreatic lipase (digests fats)

• protease (digests proteins)

trypsin formation

pancreatic secretions —> trypsinogen —>trypsin (by: enterpepsidase)

Liver

Produces Bile

Liver functions:

• metabolism of carbs, lipids and proteins

• processing drugs and hormones

• excretion of bilirubin

• synthesis of bile salts and plasma proteins

• storage of vitamins and minerals

Gallbladder

stores and concentrates bile

• can be concentrated up to 10 times before entering the small intestine

• 90% of bile is reabsorbed from the ileum and recirculates to the liver

bilirubin

gives bile yellow color

• red cell destruction, heme protein catabolism, bone marrow erythropoiesis

composition of bile

• bile salts and pigments

• lectin

• cholesterol

• NO enzymes

• pH: 7.8 -8.6

Bile Functions

• digest and absorb fats

• excretion of waste

• creates pH for pancreatic enzymes

• Bile salts and IgA antibodies inhibit bacterial growth in the small intestine

Cholecystokinin Hormone (CCK)

A hormone released with secretin when food from the stomach reaches the small intestine

• stimulates the gallbladder to release bile

• stimulates pancreatic juice

• inhibits gastric acid secretion

• reduces

emulsification

bile breaks down fat into small bits in the small intestine

gastrin

• increases gastric acid secretion

• increase gastric motility

GIP

• reduces gastric acid secretion

• Decreases gastric emptying

Somastatin

• reduces gastrin

• reduces stomach acid secretion

secretin

• inhibits gastric acid secretion

• reduces gastric emptying

• stimulates pancreatic juice and bile

Cholecystokinin

• reduces gastric acid secretion

• inhibit gastric emptying

• stimulates pancreatic juice

Motilin

• controls peristalsis

Vasoactive Intestinal Peptide (VIP)

Vasodilator

• relaxes smooth muscle

• empties water and electrolytes into pancreatic enzymes and bile

Grehlin

• stimulates appetite

Villi and Microvilli in Small Intestine

absorption