Introduction to GI

Question 1

What is the order of tissue layers within the GI tract from the outside in?

Answer 1

"SMSM"
Serosa
Muscularis
Submucosal
Mucosal

Question 2

What is the Serosa layer composed of?

Answer 2

Composed of connective tissue and covered by squamous epithelial cells.

Question 3

What is the Muscularis layer composed of and what function does it have?

Answer 3

Longitudinal and circular smooth muscle.

This layer regulates peristalsis.

Question 4

What is the submucosal layer composed of and what function does it have?

Answer 4

Contains many large blood vessels, glands, and connective tissue.

Function not spoken of.

Question 5

What is the mucosal layer composed of and what function does it have?

Answer 5

Composed of the lamina propria and lamina muscularis mucosa.

Helps coordinate bowel movements.

Question 6

What layer can the lamina propria be found in and what is it composed of?

Answer 6

Found within the mucosal layer, composed of capillaries, neurons, and immune cells.

Question 7

What layer can the lamina muscularis be found in and what action does it have?

Answer 7

Found within the mucosa layer with the action of coordinating GI motility.

Question 8

What is neurocrine communication?

Answer 8

Neurons innervate endocrine, vascular, or muscle cells to modulate there function.

Question 9

What effect does Acetylcholine have on the gut?

Answer 9

Excitatory causing:
Vasodilation
Increased secretions
Smooth muscle contraction.

Question 10

What effect does norepinephrine have on the gut?

Answer 10

Inhibitory causing:
Vasoconstriction
Inhibits smooth muscle contractions
Decreases secretions.

Question 11

Interneurons of the ENS that release serotonin have what effect on the GI?

Answer 11

Excitatory inducing:
Vasodilation
Increases smooth muscle contraction
Stimulates secretion.

Question 12

Dopamine released by the ENS stimulates what sort of reaction within the GI?

Answer 12

Dopamine is inhibitory and stops ENS neuronal firing.

Question 13

What effect does NO released from the ENS have on the GI?

Answer 13

Inhibitory causing:
Smooth muscle relaxation
(Vascular and GI)

Question 14

What effect does Vasoactive intestinal peptide (VIP) released from the ENS have on the GI?

Answer 14

VIP is inhibitory and causes smooth muscle relaxation

Vascular and GI

Question 15

Blood flow to and from the GI tract is known as ?

Answer 15

Splanchnic circulation

Question 16

Blood flows from the organs of the GI tract and eventually empties into the …?

Answer 16

Portal vein which carries the blood to the liver.

Question 17

Blood that has gone through the liver is returned to the body via the?

Answer 17

The hepatic vein.

Question 18

What is the resting slow wave?

Answer 18

A continuous depolarization followed by a repolarization that does not ellicit a contraction.

This is the membrane potential that the gut displays.

Question 19

What is the spike potential?

Answer 19

Potential for rapid depolarization in the presence of stimuli such as stretch or acetylcholine.

This stimulus will likely result in contraction/ a spike.

Question 20

What sort of GI activities are mediated by the segmental contractions of the GI?

Answer 20

Mixing activities.

Question 21

When comparing peristalsis to segmental mixing contractions, you will find that segmental mixing contractions tend to be….

Answer 21

Increased in contraction frequency leading to the movement of food toward the anus.

Question 22

When is reverse peristalsis typically seen?

Answer 22

Typically seen in storage movements within organs such as the stomach or colon.

Question 23

What is the migrating motor complex?

Answer 23

A long rhythmatic contraction that occurs during a fasting state activated by multiple stimuli.

Question 24

Which hormone plays an important role in regulating and initiating the MMC?

Answer 24

Motilin

Question 25

In addition to motilin, what nervous systems also play a role in the MMC?

Answer 25

The vagus nerve and the ENS.