DIG Secretions

Question 1

What is the functions of a parietal cell

Answer 1

Secrete HCl

Question 2

What is the morphology of a parietal cell?

Answer 2

pyramidal, microvilli at apical aspect when actively secreting, basophilic due to ^^ mitochondria

Question 3

Describe the transporters in parietal cells?

Answer 3

Basal membrane = Passive transport Cl- intracellular in exchange for HCO3- (generated by carbonic anhydrase)
Apical membrane= Active transport H+/K+ ATPase, active secretion Cl-

Question 4

What enzyme catalyses formation of H+ in a parietal cell?

Answer 4

Carbonic anhydrase

Question 5

Describe when the cephalic phase occurs during digestion

Answer 5

Sight/ smell of food (before eating)

Question 6

Describe the signalling pathways employed in the cephalic phase of digestion/ secretion

Answer 6

EXTRINSIC NERVES

1. ACh released from vagal efferents
2. Binds to muscarinic receptors on basal parietal cell for secretion
3. Also activates G cells to release gastrin (pyloric Antrum) that activates parietal cells @ funds
4. Also activates EC cells to release histamine that activates parietal cell acid release too!

Question 7

Describe when the gastric phase occurs during digestion

Answer 7

Due to stretch (mechoreceptors) or protein/ caffeine in gut (chemoreceptors)

Question 8

Describe the signalling pathways during the gastric phase of digestion/ secretion

Answer 8

LOCAL NEURAL + ENDOCRINOLOGICAL