Pharmacologic Principles

Question 1

Discuss the autonomic nervous system as it relates to anesthetic pharmacology

Answer 1

The ANS
- controls involuntary activities of the body outside consciousness
- it is divided into 2 major branches
- sympathetic : redistribution of blood flow for fight or flight
- parasympathetic : body’s maintenance needs rest and digest
- anesthesia goals: modulation of ANS

Question 2

What is the origination of preganglionic SNS fibers

Answer 2

• thoracolumbar region at the
  
  • T1 — L2 or L3 level

Question 3

Where are the cell bodies of preganglionic SNS fibers located

Answer 3

In the neurons of the spinal gray matter

Question 4

Why is sympathetic response not localized to the ganglion at the level of origination

Answer 4

This is because preganglionic sympathetic fibers synapse
- at the ganglion of the level of origination in the spinal cord and
- courses up or down to the paired ganglion
- signals are amplified and diffuse

Question 5

What is the length - location relationship of pre and post ganglionic fibers of the SNS

Answer 5

• Preganglionic SNS fibers
  
  • relatively short
  • close to CNS
• Postganglionic SNS fibers
  
  • Long course to reach target organ

Question 6

What neurotransmitter is released by all preganglionic sympathetic neurons

Answer 6

Acetylcholine

Question 7

What cholinergic receptor is found on postganglionic SNS neurons

Answer 7

Nicotinic cholinergic receptor

Question 8

What is the primary neurotransmitter released at the terminal of postganglionic SNS neurons at synapse

Answer 8

Norepinephrine

Question 9

Sympathetic neurotransmitters are synthesized from ___________ in the postganglionic sympathetic nerve ending.

What is the rate limiting step

Answer 9

Tyrosine
Rate limiting step
- conversion of tyrosine to DOPA

Question 10

What is the pathway of sympathetic neurotransmitter synthesis

Answer 10

• Tyrosine
  - catalyzed by tyrosine hydroxylase to DOPA
  - cell wall
• DOPA
  - decarboxylated to dopamine
  - cytoplasm
• Dopamine
  - B hydroxylated to norepinephrine
• Norepinephrine
  - methylated to epinephrine
  - adrenal medulla

Question 11

Which nerves give rise to the PNS

Answer 11

The PNS is of carniosacral origin
- CN III VII IX X
- SI — S4

Question 12

How does the increase in systemic resistance lead to reflex bradycardia

Question 13

Why is the risk of arrhythmias increased when epinephrine is used with halothane

Question 14

Why is Dobutamine useful in catecholamine depleted states like CHF

Answer 14

Dobutamine directly stimulates B1 receptors
- it does not rely on endogenous norepinephrine stores for its effects