GI anatomy & motility

Question 1

What medication class can have a paralyzing effect on the GI tract?

Answer 1

SSRIs

Question 2

What are the exocrine secretions of the mouth and pharynx (including salivary glands)?

Answer 2

salt and water

mucus

amylase

Question 3

What are the exocrine secretions of the esophagus?

Answer 3

mucus (lubrication)

Question 4

What are the exocrine secretions of the stomach?

Answer 4

HCl

pepsinogen

mucus

Question 5

What are the exocrine secretions of the small intestine?

Answer 5

enzymes

salt and water

mucus

Question 6

What are the exocrine secretions of the large intestine?

Answer 6

mucus

Question 7

From the outside in (toward lumen) what are the layers of the intestine (smooth muscle and nerves)?

Answer 7

Outside to in:

serosa

*longitudinal muscle*

*myenteric plexus*

*circular muscle*

*submucosal plexus*

submucosa muscularis

mucosa lamina propria epithelium lumen

Question 8

What neurotransmitter is released by parasympathetic postganglionic neurons in the enteric nervous system?

What type of receptor receives this neurotransmitter?

Answer 8

ACh released onto muscarinic receptors

Question 9

What neurotransmitter is released by sympathetic postganglionic neurons in the enteric nervous system?

What type of receptor receives this neurotransmitter?

Answer 9

Norepi released onto adrenergic receptors

Question 10

What two specific neurotransmitters are released by sensory neurons of the gut?

Answer 10

substance P

calcitonin gene-related peptide (CGRP)

Question 11

What two specific neurotransmitters are released by ascending/descending interneurons in the myenteric plexus?

Answer 11

ACh

5-HT (serotonin)

Question 12

What two specific neurotransmitters are released by secretomotor neurons in the submucosal plexus?

Answer 12

ACh

vasoactive intestinal peptide (VIP)

Question 13

The ascending pathway only talks to which kind of neurons?

Answer 13

excitatory - contraction

Question 14

The descending pathway only talks to which kind of neurons?

Answer 14

inhibitory - relaxation

Question 15

The frequency of the slow waves is the same throughout all areas of the GI tract.

T/F

Answer 15

FALSE, e.g. stomach 3/min

duodenum 12/min

ileum 8/min

Question 16

What is the ion that smooth muscle uses to generate action potentials?

Answer 16

CALCIUM NOT sodium

Question 17

What is the function of the pylorus?

Answer 17

Controls the amount and size of particles leaving the stomach

Question 18

All food empties the stomach at the same rate.

T/F

Answer 18

FALSE.

~a glucose solution is emptied quickly and immediately

~a protein solution is emptied less quickly

~a solid meal is emptied slowest and doesn’t even start until after about an hour

Question 19

Where do the MMC (migrating motor complex) and the mass movement effect occur?

Answer 19

MMC: small intestine

mass movement effect: large intestine