Pharmacology of the Autonomic Nervous System

Question 1

What are the two branches of the ANS? What is the major role of each?

Answer 1

• sympathetic: energy output; “fight or flight”

- parasympathetic: energy conservation; “rest and digest”

Question 2

How many times does a fiber from the somatic nervous system synapse once it leaves the CNS? How about a fiber from the autonomic nervous system?

Answer 2

• somatic: no synpase!

- autonomic: one synapse, creating a pre and post-ganglion

Question 3

The sympathetic branch of the ANS involves the _________ regions; the parasympathetic branch involves the __________ regions.

Answer 3

• sympathetic: thoracicolumbar

- parasympathetic: craniosacral

Question 4

T or F: the CNS uses ACh to communicate to ALL branches of the PNS.

Answer 4

• true!
• ACh is used to send signals to the somatic branches (no synapse), as well as to the autonomic branches (one synapse, once it reaches the synapse, the communication method can change)

Question 5

What organ of the autonomic nervous system does NOT have a synapse?

Answer 5

• the adrenal medulla

- all other fibers of the ANS do have a synapse

Question 6

What are the two types of cholinergic receptors?

Answer 6

• muscarinic and nicotinic

Question 7

What role does Ca2+ play in signaling?

Answer 7

• Ca2+ influx results in the release of ACh via exocytosis

Question 8

Acetylcholine Esterase (ACh-E)

Answer 8

• breaks down ACh to cut off the signal transduction

- opposite function of choline acetyltransferase

Question 9

Skeletal muscles are innervated by the ________ NS and have ________ receptors.

Answer 9

• somatic nervous system; nicotinic receptors

Question 10

Choline Acetyltransferase

Answer 10

• makes ACh from choline and acetyl CoA

- opposite function of ACh esterase

Question 11

Nicotinic receptors are _________, while muscarinic receptors are ___________.

Answer 11

• nicotinic = ligand-activated cation channels

- muscarinic = G-protein coupled receptors

Question 12

There are five types of muscarinic receptors (M1 –> M5), which are stimulatory and which are inhibitory?

Answer 12

• stimulatory: M1, M3, and M5

- inhibitory: M2 and M4

Question 13

What are the effects of parasympathetic innervation?

Answer 13

• S.L.U.D.G.E. - B.B.B.

- salivation, lacrimation, urination, defecation, gastro-emesis, bronchorrhea, bronchospasm, bradycardia

Question 14

In general terms, the parasympathetic NS is associated with ________ receptors and the sympathetic NS is associated with ________ receptors; both have _________ receptors at their ganglionic synapse.

Answer 14

• parasympathetic: muscarinic
• sympathetic: adrenergic
• ganglionic synapse: nicotinic

Question 15

What are the four types of adrenergic receptors? What is the function of each?

Answer 15

• alpha-1: smooth muscle contraction
• alpha-2: inhibits release of norepinephrine (negative feedback)
• beta-1: cardiac muscle contraction
• beta-2: smooth muscle relaxation

Question 16

Given that we use Beta Blockers to treat HTN, what is a common side effect of these drugs? What can we do in these situations?

Answer 16

• beta-blockers will block beta-1 and beta-2 adrenergic receptors; blocking beta-1 will result in cardiac relaxation, while blocking beta-2 will result in smooth muscle contraction –> therefore, a common side effect is difficulty breathing
• to avoid this, we can give the patient a beta-1 specific blocker

Question 17

Which effectors use muscarinic receptors?

Answer 17

• all effectors of the parasympathetic NS

- sweat glands of the sympathetic NS

Question 18

Which effetors use adrenergic receptors?

Answer 18

• all effectors of the sympathetic NS, EXCEPT for the sweat glands