Introduction to GI physiology

Question 1

what are the intrinsic neurons of the GI tract?

Answer 1

ENS neurons - motor, sensory, associative, interofugal

Question 2

what are the extrinsic neurons of the GI tract?

Answer 2

sympathetic, parasympathetic, sensory input

Question 3

what is the role of dopamine in the ENS?

Answer 3

inhibitory - inhibits ENS neuronal firing

Question 4

what is the role of serotonin in the ENS?

Answer 4

excitatory - induces vasodilation, increases smooth muscle contraction, stimulates secretion

Question 5

what is the role of Ach in the GI tract?

Answer 5

excitatory - induces vasodilation, increases smooth muscle contraction, stimulates secretion

Question 6

what is the role of NO and VIP in the GI tract?

Answer 6

inhibitory - smooth muscle relaxation

Question 7

what factors increase vasodilation of the GI tract?

Answer 7

PNS, NTs such as NO / VIP, low oxygen, hyperosmolarity

Question 8

what factors decrease blood flow to the GI tract?

Answer 8

SNS innervation of vascular smooth muscle (NE, a-adrenergic receptors)