FTM 73-74 Autonomic Nervous System Physiology

Question 1

What do all somatic motor neurons release? How do their pathways differ from the ANS neurons? What do the ANS neurons release?

Answer 1

Somatic motor neurons are 1 long, heavily myelinated axon extending from the CNS to the effector and it always releases ACh. The ANS pathway has a lightly myelinated preganglionic neuron and an unmyelinated postganglionic neuron. The preganglionic neuron always releases ACh and the postganglionic neuron may release epinephrine/norepinephrine or ACh.

Question 2

How does the sympathetic response affect the adrenal medulla and blood flow to the organs?

Answer 2

Question 3

What bodily functions does the PSNS usually control? What happens if the PSNS is blocked?

Answer 3

Question 4

Answer 4

Question 5

What tissues receive only SNS or PSNS stimulation?

Answer 5

Question 6

Answer 6

Question 7

The neurotransmitter that sympathetic fibers release on their target tissues is almost always ________. What is the exception?

Answer 7

Question 8

What portion of the adrenal gland is innervated by the preganglionic sympathetic fibers? What types of cells are these?

Answer 8

The middle portion of the adrenal gland called the adrenal medulla

chromaffin cells

Question 9

What are prevertebral ganglia?

Answer 9

sympathetic ganglia which lie between the paravertebral ganglia and the target organ.

Question 10

Answer 10

Question 11

The physiological event elicited by a neurotransmitter depends solely on the _____________.

Answer 11

Receptor

Question 12

What does Hexamethonium do?

Answer 12

It blocks the nicotinic receptors of the ANS

Question 13

Cholinergic receptors respond to what? What classes are they divided into?

Answer 13

Acetylcholine

Nicotinic and Muscarinic

Question 14

All nicotinic receptors are _________________________________.

All muscarninic receptors are _______________________________.

Answer 14

ligand-gated cation-selective channels

GPCRs

Question 15

What is always the effect of ACh binding a nicotinic receptor? Where are these receptors usually found?

Answer 15

Question 16

What is the effect of ACh binding a muscarinic receptor? Where are these receptors usually found?

Answer 16

Question 17

What happens to acetylcholine in the synaptic cleft?

Answer 17

Question 18

Describe the type of voltage response seen with nicotinic, M2, M1, and Substance P receptors.

Answer 18

Question 19

Describe the structure and function of the basic nicotinic receptor.

Answer 19

Question 20

Where are the different types of nicotinic receptors found?

Answer 20

CNS and ganglionic receptors are N₂/N_n

The NMJ receptors are N₁/N_m

Question 21

Explain why the nicotinic response is sharp and quick.

Answer 21

Question 22

How can nicotinic receptors desensitize? How often does this happen? Why?

Answer 22

Question 23

When a nicotinic receptor is opened, what happens?

Answer 23

Na and K are free to move through it and depolarize the membrane. More Na comes in then K goes out

Question 24

What is the mnemonic to remember what signaling pathways the different muscarinic receptors activate?

Answer 24

QIQIQ

M1 - Gq

M2 - Gi

M3 - Gq

M4 - Gi

M5 - Gq

Question 25

What is mnemonic to remember what the different adrenergic receptors do?

Answer 25

QISSS α1 - Gq α2 - Gi ß1 - Gs ß2 - Gs ß3 - Gs

Question 26

Describe how vasodilation occurs?

Answer 26

PSNS activates an M3 receptor on an endothelial cell which will, in turn, lead to the production fo nitric oxide that will freely diffuse into a smooth muscle cell, activate guanalyl cyclase, and cause the muscle to relax

Question 27

Facts to know about adrenergic receptors

Answer 27

Question 28

What is a presynaptic receptor?

Answer 28

A receptor found in the synaptic cleft but in the membrane of the presynaptic neuron. It usually serves to sense the presence of the neurotransmiiter released by the presynaptic neuron and then signal to that neuron to stop releasing it

Question 29

Discuss catecholamine synthesis and storage in a neuron.

Answer 29

A Na+/tyrosine symporter brings Tyrosine into the neuron. Tyrosine hydroxylase the converts tyrosine into L-DOPA, _this is the rate limiting step_. A neurotransmitter vesicle then transports tyrosine, dopamine precursors, and dopamine ß-hydroxylase into itself using the VMAT (vesicular mono amine transporter) which uses an H+ gradient. NE synthesis finished in the vesicle before it is released into the synaptic cleft

Question 30

Discuss ACh synthesis and storage in a neuron.

Answer 30

Acetyle CoA (from glycolysis) and choline (reuptake via Na+ symporter, _rate limiting step_) are combined into ACh by choline acetyltransferase. Vesicular storage of ACh by action of a ACh-H+ antiporter in a vesicle membrane. Vesicel fuses with membrane upon Ca++ influx

Question 31

What type of receptor can act as both a pre and post synaptic receptor?

Answer 31

α2

Question 32

What are the 4 ways that catecholamines are cleared from the synaptic cleft?

Answer 32

Question 33

Answer 33

Question 34

Describe the autonomic control of the bladder

Answer 34

Question 35

What are some of the major effects triggered by α1 receptors

Answer 35

Question 36

What are some of the major effects triggered by α2 receptors?

Answer 36

Question 37

What are some of the major effects triggered by ß1 receptors?

Answer 37

Question 38

What are some of the major effects triggered by ß2 receptors?

Answer 38

Question 39

What are the overall effects of catecholamines on metabolism?

Answer 39

Question 40

Where are ß3 receptors found?

Answer 40

Adipose tissue

Question 41

For the adrenergic receptors

Answer 41

Question 42

For the muscarinic receptors

Answer 42