Digestion

Question 1

What is ptyalin?

Answer 1

Salivary amylase. Hydrolyzes starch

Question 2

What are the two types of glands in the stomach?

Answer 2

Gastric and pyloric

Question 3

What are the cell types in the gastric glands?

Answer 3

Mucous cells: produce mucous
Chief cells: Secrete pepsinogen (zymogen of pepsin activated by H+ from HCl, which cleaves near aromatic aa’s. Most active at pH 2)
Parietal cells: secrete HCl for pH of 2

Question 4

What’s the function of pyloric glands?

Answer 4

Secrete gastrin, a hormone that induces stomach to secrete more HCl and to mix

Question 5

Describe pancreatic juice

Answer 5

Mixture of enzymes in bicarbonate, which neutralizes acid and sets pH for enzymes at 8.5. Breaks down carbs, proteins, and fats

Question 6

Describe bile

Answer 6

Secreted in response to CCK (cholecystokinin). Emulsifies fat with bile salts (made from cholesterol)

Question 7

What’s a key difference between fats and sugars + aa’s at first absorption and what happens to fats?

Answer 7

Fats bypass hepatic portal circulation. They can reform in intestinal cells into tryglycerides, packaged with cholesterol into insoluble chylomicrons which enter lymphatic circulation through lacteals, then enter venous circulation through lymphatic duct. Released into bloodstream as LDL, taken up by liver and repackaged as HDL

Question 8

Describe mechanisms of vitamin absorption

Answer 8

Fat or water soluble. ADEK are fat soluble. Bad fat digestion = bad ADEK absorption

Question 9

What’s key about enterokinase?

Answer 9

Secreted by small intestine to convert trypsinogen to trypsin, which then activates the other zymogens.