Process of Digestion: Pyloric Sphincter to Small intestine

Question 1

Neutralization

Answer 1

-alkaline bile neutralizes the chyme before it enters the small intestine

Question 2

Digestion in the small intestine

Answer 2

• most chemical digestion takes place
• enzymes produced in accessory organs
• enzymes produced in the small intestine
• physical digestion and propulsion continue
• most absorption takes place here

Question 3

Accessory organs and the duodenum

Answer 3

• common hepatic duct (from liver)
• cystic duct (from gallbladder)
• fuse to bile duct
• bile duct and main pancreatic duct fuse to the hepatopancreatic ampulla with sphincters that control releases of juices

Question 4

Bile function

Answer 4

• emulsified fats into small droplets
• neutralizes chyme
• produced by hepatocytes of the liver, stores in the gallbladder
  (0. 9 L produced per day)

Question 5

Bile composition

Answer 5

• contains H2O, bile salts, pigments (bilirubin), phospholipids, electrolytes
• bile salts and phospholipids are amphipathic
• bile salts reabsorbed in ileum, returned to the liver

Question 6

Gallstones

Answer 6

Can form when:
-levels of bilirubin or cholesterol in the bile are too high
-incomplete and infrequent emptying of the gallbladder
(Inflammation: pancreatitis)

Question 7

Pancreatic juice

Answer 7

• produced by acini of pancreas

- composed of: H2O, salts, Na, HCO3-, digestive enzymes

Question 8

Enzymes of pancreatic juice

Answer 8

• enzymes that digest carbs, nucleic acids, and lipids released in active form
• enzymes that digest proteins released are inactive
• trypsin activated by enzymes on brush border of duodenum’s mucosa
• trypsin activates other protein digesting enzymes

Question 9

Mechanical digestion and propulsion in the small intestine

Answer 9

• peristalsis

- segmentation

Question 10

Peristalsis of the small intestine

Answer 10

• promoted by hormone motilin

- forces chyme through small intestine through ileocecal sphincter

Question 11

Segmentation

Answer 11

• repeated relaxation and contraction of smooth muscles
• mixed chyme with intestinal juices
• pushes chyme against mucosa for absorption

Question 12

Chemical digestion of the small intestine

Answer 12

• mucosal epithelium bears enzymes (brush border enzymes)
• activate pancreatic trypsin
• break small carbs and peptides into monosaccharides and amino acids
• bulk of chemical digestion done by pancreatic enzymes

Question 13

Absorption in small intestine

Answer 13

• H2O absorbed by diffusion (90%)
• most carbs and proteins are absorbed by using active transport (as monomers that pass into capillaries)
• for lipids, short chained fatty acids diffuse directly into capillaries
• long chain fatty acids are packaged into micelles with cholesterol and fat soluble vitamins
• transported by the PM
• reformed into tryglycerides inside cell
• packaged with protein coat into chylomicron
• chylomicrons diffuse into lacteals