Physiology Of The ANS

Question 1

What are the two types of receptors neurotransmitters can bind to?

Answer 1

Ionotropic (allow movement of ions)

Metabotropic (G proteins)

Question 2

Where is the preganglionic cell body located in either sympathetic or parasympathetic systems?

Answer 2

Contained within the CNS and its axon exits the CNS to then enter a ganglion in the periphery

Question 3

Where are parasympathetic ganglia located?

Answer 3

Close to their target organs

Question 4

Where are sympathetic ganglia located?

Answer 4

In the periphery (paravertebral ganglion or sympathetic chain)

Question 5

Which neurotransmitter is released from the pre-ganglionic fiber in both sympathetic and parasympathetic systems?

Answer 5

Acetylcholine

Question 6

What type of receptor does ACh bind to on the postganglionic cell in both systems?

Answer 6

Nicotinic cholinergic channel on the postganglionic dendrites

Question 7

Describe the steps that occur at a synapse between a pre and post ganglionic cell in both systems

Answer 7

1. Pre-ganglionic fiber releases ACh
2. ACh diffuses across the synaptic cleft and binds to a nicotinic cholinergic channel on the postganglionic cell
3. Channel opens allowing Na to enter the postganglionic cell
4. Cell is depolarized and now more excitable than previously
5. AP forms in the postganglionic axon

Question 8

Which neurotransmitter is released by parasympathetic ganglionic fibers when synapsing with target tissue?

Answer 8

ACh

Question 9

What receptor does ACh bind to during a synapse between a parasympathetic postganglionic fiber and its target tissue?

Answer 9

Muscarinic cholinergic receptors on all target tissues

Question 10

What are the types of muscarinic cholinergic receptors?

Answer 10

Odd numbered: M1R, M3R and M5R

Even numbered: M2R and M4R

Question 11

What neurotransmitter is released from a sympathetic post ganglionic fiber when it synapses with its target tissue?

Answer 11

Norepinephrine

Question 12

What type of target tissue receptor does NE bind to once released from the sympathetic post ganglionic cell?

Answer 12

Adrenergic receptors

Question 13

What are the different types of adrenergic receptors?

Answer 13

Alpha (1 and 2)

Beta (1, 2 and 3)

Question 14

The odd numbered muscarinic receptors are coupled to what type of protein?

Answer 14

Gq protein which leads to an increase in IP3 and DAG resulting in increased intracellular Ca levels

Question 15

Which protein are even numbered muscarinic receptors coupled to?

Answer 15

Gi/o which decreases adenylyl cyclase activity and cAMP levels

Question 16

Which adrenergic receptor is coupled to Gq?

Answer 16

Alpha 1

Question 17

Which adrenergic receptor is coupled to Gi?

Answer 17

Alpha 2

Question 18

Which adrenergic receptor is coupled to Gs?

Answer 18

Beta 1, 2 and 3

Question 19

Where are beta 3 adrenergic receptors primarily found?

Answer 19

In white adipose tissue where it activated lipolysis and in brown adipose tissue where it causes heat production through uncoupling

Question 20

When discussing the role of the adrenal medulla in the sympathetic NS, where does its pre-ganglionic fiber travel?

Answer 20

Through the sympathetic chain without synapsing with any fibers in the ganglion and then travels to the adrenal medulla

Question 21

The adrenal medulla contains clusters of what type of cell?

Answer 21

Chromaffin cells which synthesize catecholamines primarily epinephrine

Question 22

What are the steps of the synapse that occurs between sympathetic preganglionic fibers and chromaffin cells in the adrenal medulla?

Answer 22

1. Pre-ganglionic fiber release ACh to the adrenal medulla
2. ACh binds to nicotinic cholinergic receptor on the chromaffin cell
3. Channel opens and allows Na to flow into the cell
4. Chromaffin cell depolarizes and releases epinephrine into the blood in order to add to the sympathetic response

Question 23

What receptor will epinephrine released from the adrenal medulla bind to?

Answer 23

Either alpha or beta adrenergic receptors most likely in the blood (ex. To cause blood clotting)