GI Part1

Question 1

What are the cells that produce Hcl, Mucus/Bicarb, Histamine, and Gastrin and what is the function of each of these?

Answer 1

“1. Parietal - Hcl - protein digestion, sterilization and nutrient absorption

2. Mucus/Bicarb - surface epithelial cell - gastroprotection
3. Histamine - ECL cells - Up Hcl
4. Gastrin - G cell - Up Hcl”

Question 2

What are the 3 pathways of acid regulation and what receptors are used? What inhibits acid secretion? Include the how.

Answer 2

Paracrine, endocrine and neuronal pathways. Ach and gastrin directly activate parietal cells to up IC calcium. Histamine activates parietal cells by increasing cAMP (Gs). Gastrin also stimulates ECL cells to release histamine. PGE2 inhibits via Gi.

Question 3

What are the receptors on the parietal cell that influence acid secretion? What NT influences this receptor?

Answer 3

“1. M3 - Ach

2. CCKB - Gastrin
3. H2 - Histamine”

Question 4

What are the receptors on the ECL cell that influence histamine secretion?

Answer 4

Ach, G

Question 5

What pathway of regulation does Ach fall under? Prostaglandins? What are the functions of prostaglandins in the stomach?

Answer 5

Neurocrine - Ach, Paracrine - prostaglandin. Prostaglandin up mucus and bicarb secretion, gastric blood flow. Down Hcl secretion.

Question 6

What is a peptic ulcer?

Answer 6

Break in protective mucosal lining of lower esophagus, stomach and duodenum.

Question 7

What is the GI ulcer of greatest frequency? What is a stress ulcer?

Answer 7

Duodenal ulcer - most frequent. Stress ulcer - peptic ulcer due to illness, systemic trauma, neuronal injury or emotion.