Gastrointestinal

Question 1

Which cells are the pacemaker cells of the GI smooth muscles and where are they located?

Answer 1

Interstitial Cells of Cajal are the pacemakers

• Positioned between muscle cells; most abundant in longitudinal muscles

Question 2

What is the rate of segmentation in different parts of the GIT?

Answer 2

• 3x/min in stomach
• 12x/min in the duodenum
• 8x/min in ileum

Question 3

What is schistosomiasis?

Answer 3

*Schistosomiasis – parasitic worm that takes residence in GIT (in superior mesenteric vein)
Often causes liver fibrosis because worm produces eggs that travel through the hepatic portal vein –> fibrosis

Question 4

What is the RMP and threshold of AP for smooth muscles cells in the GIT?

Answer 4

Threshold -40 mV (RMP ~-50 to -60 mV)

Question 5

Which cells have CCK-B receptors? CCK-A?

Answer 5

CCK-B receptors (ECL and Oxyntic cells)

CCK-A receptors (‘D’ cells)

Question 6

Where are G cells located?

Answer 6

• Distal stomach
• Pancreas
• Duodenum

Question 7

Name an example of a single-cell gland

Answer 7

Mucus glands

Question 8

Name 4 pancreatic enzymes

Answer 8

Lipase, a-amylase, ribonuclease, deoxyribonuclease