Ch 62-64

Question 0

What are the “pacemaker cells” of the GI?

Answer 0

Interstitial cells of Cajal

Question 1

When action potential is initiated in the GI within muscle mass, where can it travel?

Answer 1

It can travel in all directions

Question 2

How long do GI spike potentials last?

What causes this?

Answer 2

GI spike potentials last much longer than most others due to calcium-sodium channels that are slow to open and
close

Question 3

What does Auerbach’s (myenteric) plexus (outer, between

longitudinal & circular muscle layers) control?

Answer 3

Movement

Question 4

What does Meissner’s (submucosal) plexus (inner) control?

Answer 4

secretions & blood flow

Question 5

In the Extrinsic Nervous System are Parasympathetic fibers excitatory or inhibitory?

Answer 5

Excitatory: increase motility & secretion

Question 6

In the Extrinsic Nervous System are Sympathetic neurons excitatory or inhibitory?

Answer 6

Inhibitory: decrease motility & secretion

Question 7

Where do Preganglionic Sympathetic neurons pass through sympathetic chain and where do they synapse?

Answer 7

pass through via splanchnic nerves and synapse in prevertebral ganglia

Question 8

Do preganglionic or postganglionic sympathetic neurons have cholenergic r/c or adrenergic r/c?

Answer 8

Preganglionic sympathetic = Cholinergic
Postganglioninc sympathetic = Adrenergic; norepinephrine and epinephrine generally inhibit activity. Strong sympathetic stimulation can block food movement

Question 9

What effect does the Sympathetic system have on blood vessels? Gut wall? Secretatory cells? Sphincter muscles?

Answer 9

Blood vessels = vasoconstriction
Gut = Inhibition
Secretory cells = inhibition
Sphincter muscles = *Excitatory: Stimulating, or exciting the contraction of a sphincterinhibits the movement of food