Week 3

Question 1

Regulation of Gastric Function:

Answer 1

1) Cephalic Response (Brain)
- 30% of stomach activity
- see, smell, taste food
2) Gastric Response
- 60%of stomach activity
- stretch (vasovagal), peptides in stomach
3) Intestinal Response
- 10% of stomach activity

Question 2

Chief Cells

Answer 2

1) Secrete Pepsinogen (zymogen)
- plus the presence of acid= cleavage into pepsin (active)
- endopeptidsase- cuts in the center of peptide
- only active @ acidic pH (~3-1)
- above pH of 3 enzyme turns off
- above pH of 7 enzyme is permanately denatured

Question 3

Protection of Stomach Lining

Answer 3

1) Mucus layer between surface of stomach and lumen
- made up of mucus and HCO3- (alkaline)
- produced by surface epithelium cells and mucus cells
2) SE cells use co transporter to move Na and Bicarbonate in
- get bicarbonate from baso-lateral surface (Blood) from same cotransporter

Question 4

Mucus

Answer 4

1) Type of glycoprotein called mucin

- hydroscopic-Negative charge so attracts Na+ and pulls water toward it