Unit 6a GI Secretions

Question 1

What is the main function of parietal cells in the stomach?
a) Secrete mucus
b) Secrete pepsinogen
c) Absorb vitamin B12
d) Secrete hydrochloric acid (HCl)

Answer 1

d) Secrete hydrochloric acid (HCl)

Explanation: Parietal cells pump H+ into the lumen, creating acidic conditions (as low as pH 1) to aid digestion and kill microbes.

Question 2

Which transporter is essential for acid secretion in parietal cells?
a) H+/K+-ATPase
b) Na+/K+-ATPase
c) SGLT1
d) CFTR

Answer 2

a) H+/K+-ATPase

Explanation: This proton pump exchanges intracellular H+ for extracellular K+, allowing acid to be secreted into the gastric lumen.

Question 3

What does the pancreas secrete to neutralize stomach acid in the duodenum?
a) Bile salts
b) Mucus
c) Bicarbonate (HCO3⁻)
d) Hydrochloric acid

Answer 3

c) Bicarbonate (HCO3⁻)

Explanation: Pancreatic duct cells secrete bicarbonate, which neutralizes acidic chyme entering from the stomach.

Question 4

What ion channel is defective in cystic fibrosis, affecting GI secretions?
a) H+/K+-ATPase
b) ENaC
c) NKCC
d) CFTR

Answer 4

d) CFTR

Explanation: CFTR is a chloride channel important for secreting Cl− into ducts, pulling Na+ and water with it. Its dysfunction leads to thick mucus and blocked ducts.

Question 5

What do goblet cells secrete and what stimulates them?
a) Bicarbonate; sympathetic input
b) Mucus; parasympathetic, neuropeptides, cytokines
c) Enzymes; parasympathetic input
d) HCl; gastrin

Answer 5

b) Mucus; parasympathetic, neuropeptides, cytokines

Explanation: Goblet cells in the intestine secrete protective mucus in response to various signals including inflammation.