Gastrointestinal Physio L7-8

Question 1

What are the functions of the GI tract?

Answer 1

• Secretion
• Digestion
• Absorption
• Motility
• Storage

Question 2

How does the GI tract coordinate the 5 functions?

Answer 2

By the intrinsic and extrinsic control system.

Question 3

Where is the intrinsic control system?

Answer 3

Located in the wall of the GI tract
- enteric nervous system
- GI hormones

Question 4

Where is the extrinsic control system?

Answer 4

Located outside
- Vagus & splanchnic nerves
- Non-GI hormones

Question 5

True or False. The GI tract has his own nervous system.

Answer 5

True

Question 6

The _______ nervous system is a component of the autonomic nervous system.
A. Intrinsic
B.
C. Enteric
D.

Answer 6

C
- The enteric nervous system is a component of the ANS.
- It is located within the GI wall & enables autonomic regulation of GI functions.

Question 7

The ____________ plexus regulates mucus secretion and food absorption.
A. Meissner
B. Auerbach
C.
D. Myentericus

Answer 7

A
- The MEISSNER’s (Submucosus) plexus regulates mucus secretion and food absorption.
- It is located between the submucosa and circular musculature

Question 8

The ___________ plexus has control of the muscular activity.
A. Meissner
B.
C. Myentericus
D.

Answer 8

C
- The MYENTERICUS plexus has control of the muscular activity (tone and contractions rhythm)
- It is located in the muscularis external, between longitudinal and circular musculature.

Question 9

How are the cells arranged in the enteric nervous system?

Answer 9

• Cells are arrange in bundles of as many as 1000 parallel fiber (longitudinal or circular arranged)
• Within each bundle, muscle fibers are electrically connected w/one other through gap junctions
• Each bundle of smooth muscle fibers is partially separated from the next by loose connective tissue, but the muscle bundles fuse w/one another at many points & work as a synctium (“together cell”)

Question 10

True or False. Enteric neurons and typical neurons secrete their neurotransmitters from the same location.

Answer 10

False
- Unlike typical neurons, enteric neurons secrete their neurotransmitters from varicosities located on often lengthy axonal collaterals or branches
- An ant Eric neuron affects a wider area compared to the typical CNS neuron.

Question 11

3 cells?

Answer 11

• Sensory nerve cells
• Interneurons
• Motor neurons

Question 12

Sensory nerve cells:
A. Process signals coming from other nerve cells or from the CNS & propagate them to other neurons (motor neurons)
B. Induce a change in the GI tract in response to a stimulus
C. Detect changes/stimuli and regulate function.

Answer 12

C
- Sensory nerve cells detect changes/stimuli & regulate function.
- The axons go to the other enteric nerve cells and to the CNS

Question 13

What are the types of sensory nerve cells?

Answer 13

Mechanosensitive cells (mechanoreceptors) & Chemosensitive cells (chemoreceptors)

Question 14

Interneurons:
A.
B.
C.

Answer 14

A

Question 15

Motor Neurons:
A.
B.
C.

Answer 15

B

Question 16

What are the 3 types of motor neurons?

Answer 16

Muscle, secrete, and vaso motor

Question 17

Where is the vaso motor neuron located?
A. In the plexus myentericus
B. In the plexus submucosus
C. In both plexuses
D. In neither plexus

Answer 17

C
- Muscle = A
- Secreto = B
- D = Not true