Module 1 Digestive System

Question 1

Functions of the digestive sytem

Answer 1

acquire food
process food
extract usable nutrients from food
void unusable wastes

Question 2

GI Tract consists of

Answer 2

Mouth, esophagus, stomach, Small intestine, Large intestine, anus

Question 3

How does the nervous system affect digestive motility?

Answer 3

the rate of movement or rate of peristalsis

Question 4

How does the nervous system affect digestive blood supply?

Answer 4

which affects diffusion gradients and the performance of smooth muscle

Question 5

The parasympathetic input to the digestive system includes

Answer 5

involuntary stimulation of smooth muscle. The parasympathetic system increases digestive performance mostly by increasing motility and enzyme secretion.

Question 6

The sympathetic input to the digestive system includes

Answer 6

involuntary stimulation of smooth muscle. The sympathetic system decreases digestive performance mostly by decreasing motility, enzyme secretion, and blood supply.

Question 7

The ENS (Enteric Nervous System) contains 2 plexuses

Answer 7

submucosal or Meissner’s plexus

myenteric or Auerbach’s plexus:

Question 8

myenteric or Auerbach’s plexus:

Answer 8

This nerve network lies between the longitudinal and circular muscle layers and controls motility.

Question 9

submucosal or Meissner’s plexus:

Answer 9

This nerve network lies in the submucosal region of the wall and controls the function of the inner wall by influencing secretions, blood flow, and ton

Question 10

Myenteric Plexus stimulation affects movement through at least 5 inhibitory or excitatory pathways:

Answer 10

Increased tonic contraction (tone) of gut wall
Increased amplitude of rhythmic contractions
Increased frequency of rhythmic contractions
Increased velocity of conduction of excitatory waves
Inhibition of sphincters (via an inhibitory NT such as vasoactive intestinal polypeptide) which impede movement from region to region; ie: pyloric sphincter between stomach and duodenum (so they remain open and food moves more easily)

Question 11

Submucosal Plexus Function

Answer 11

local control
Intestinal secretion
Absorption
Contraction of the submucosal muscle (controls folding of GI mucosa)

Question 12

Neurotransmitters of Enteric Neurons

Answer 12

Acetylcholine: 
Norepinephrine: 
ATP
Serotonin
Dopamine
Cholecystokinin
Vasoactive intestinal polypeptide
Somatostatin
Leu-enkephalin
Met-enkephalin
Bombesin
Epinephrine

Question 13

Acetylcholine function in Enteric neurons

Answer 13

excites gut (parasympathetic)

Question 14

Norepinephrine function in Enteric Neurons

Answer 14

inhibits gut (sympathetic)

Question 15

Epinephrine function in Enteric Neurons

Answer 15

released by adrenal medulla, travels by bloodstream, inhibits gut

Question 16

Chewing

Answer 16

major mechanical breakdown process in the mouth involves the jaw muscles, the teeth, and the tongue

Question 17

Pressure in teeth when chewing/moving the jaw

Answer 17

The jaw muscles are capable of generating 55 lbs of pressure with on the incisors and 200 lbs of pressure on the molars.

Question 18

Neurons involved in chewing

Answer 18

a simple reflex whose motor nerve is the 5th cranial or trigeminal nerve. The reflex is integrated in the medulla/pons of the brainstem.