GI Motility

Question 0

How do gap junctions help create unitary smooth muscle in the GI tract?

Answer 0

They electrically couple the smooth muscle cells by providing pathways of low resistance to the spreading of an action potential.

Question 1

Which contractile tissues of the GI tract ARE NOT smooth muscle?

Answer 1

1. Pharynx
2. Upper 1/3 of the esophagus
3. External anal sphincter

Question 2

What are the two different types of contraction? In what areas of the GI tract would you find each of these contraction types?

Answer 2

1. Phasic contraction: esophagus, stomach and intestine (found in any location responsible for mixing and propelling food)
2. Tonic contractions: found in three sphincters (lower esophageal, ileocecal and internal anal sphincter) and the upper portion of the stomach (orad stomach).