Small intestine

Duodenum Jejunum Ileum

Pancreatic secretion Bile secretion Secretion of small intestine

Exocrine portion: acinar cells :enzyme duct cells:electrolyte solution Endocrine portion insulin glucagon

Pancreatic juice

Pancreatic amylase

Pancreatic lipase Only enzyme secreted throughout the entire digestive system that can accomplish digestion of fat

Pancreatic proteolytic enzyme

Acute pancreatitis

Regulation of pancreatic sercretion

Regulation of pancreatic sercretion

Regulation of pancreatic sercretion

Regulation of pancreatic sercretion cholecystokinin

↓ ↓ ↓ ↓ ↓ ↓ ↑ Secretin release from duodenal mucosa Acid in duodenal lumen Fat and protein products in duodenal lumen ↓ ↓ ↑ Secretin release from duodenal mucosa ↑CCK release from duodenal mucosa ↓ ↓ Pancreatic duct cells Pancreatic acinar cells ↓ ↓ ↑Secretion of aqueous NaHDO3 solution into duodenal lumen ↑ Secretion of pancreatic digestive enzymes into duodenal lumen

Bile secretion

Secretion of bile

Composition of bile secretion Hepatic bile : pH:7.4 reletively dilute,yellow and alkaline Bile in gallbladder pH:6.8 brown and acidic Difference result from actively absorption of H2O and CO2 and concentrates this fluid.

Composition of bile secretion Cholesterol,phospholipids,lecithin,bile pigments and most important a group of substances termed bile salts Double ecotropic molecular Lipid-soluble portion Water-soluble portion(negative charge)

Function of bile salt

Function of bile salt 1.Emulsification:aid digestion refers to bile salts’ ability to convert large fat globules into a lipid emulsion(fat droplets in the aqueous chyme).

Function of bile salt 2,micellar formation:aid absorption bile salts interact with cholesterol and lecithin to form micellars to facilitate the absorption for insolute fat productions. Hydrophobic core Hydrophilic shell

Hydrophobic core Hydrophilic shell

Gallstones Excess cholesterol precipitates into microcrystals that can aggregate into gallstones:75% Bilirubin:25% The amount of cholesterol that can be carried in micellar formation depends on the relative amount of bile salts and lecithin in comparison to cholesterol

Cholecystitis

Regulation of bile secretion Choleretic

Small intestinal juices Brunners gland

Small intestinal juices Brunners gland Crypts of lieberkuhn

Small intestinal juices

Small intestinal juices

Motility of small intestine

Segmentation

Peristalsis ＆peristalsis rush

Movement of small intestine

Defecation reflex

Quenstion: 1 If stomach is removed,what will happen? 2 How to control HCl? 3 why is the small intestine the most important portion for ingestion and absorbtion? 4 how does a hamberger travel in your digestive gut