Stomach

Question 1

HCL…

Answer 1

Aids digestion by activating pepsinogen
Aids breakdown of connective tissue
Non specific defence mechanism

Question 2

Vagal actions and effects on HCL production

Answer 2

GRP on gastrin acts on CCK2 on histamine and parietal cells
Ach on muscarinic receptors on histamine and parietal cells (increases Ca2+)
Histamine acts on H2 receptors on parietal cells to increase cAMP.
Somatostatin inhibits gastrin release (D cells in Antrum)

Question 3

Inhibition of gastric secretions

Answer 3

Removal of peptide fragments
Removal of food -> decrease pH, when pH is bellow 2 gastrin release inhibited by somatostatin.
Distension of duodenum-> hormone release->cholecystokinin->inhibits gastrin release

Question 4

Protection of gastric mucosa

Answer 4

Luminal membranes of gastric mucosa impermeable to H+
pH bellow 2 inhibits gastrin release
Mucus release from surface epithelium
Rapid repair, prostaglandin production, local vasodilation.

Question 5

Types of gastric mucosa and their secretions.

Answer 5

Surface epithelial, mucus
Mucous neck, mucus
Parietal, HCL and intrinsic factor
Chief cells, pepsinogen