ANS A&P Flashcards
The peripheral nervous system consists of how many spinal nerve pairs?
31 pairs of spinal nerves
Another name for the ANS is the:
Visceral nervous system
What are the three divisions of the ANS?
Sympathetic
Parasympathetic
Enteric
Alpha 2 receptors are found in three locations:
Presynaptic
Postsynaptic
Plateletes
Why does precedex cause a biphasic response?
Stimulation of A2 receptors in the vasculature causes hypertension
CNS depression (which kicks in later) leads to reduced sympathetic output
A2 receptor stimulation on platelets causes:
increased aggregation
Which enzyme metabolizes cAMP?
PDE3
PDE-3 inhibitors are also called:
inodilators
What effect does cAMP have in the myocardium?
- Increased intracellular calcium causes increased contractility
- Accelerates the return of calcium to the sarcoplasmic reticulum, which accelerates relaxation (lusitropy)
What effect does cAMP have in the vasculature?
Inhibits myosin light chain kinase:
Vasodilation
Decreased SVR
What is the primary mechanism of NE removal from the synaptic cleft?
Reuptake
All sympathetic preganglionic nerves are __________ fibers
myelinated B fibers
Preganglionic sympathetic fibers exit the spinal cord via the _________
ventral rami
Once they exit the spinal cord, sympathetic fibers enter the sympathetic chain via the _________
White ramus (white because it’s myelinated)
Once inside the sympathetic chain, preganglionic nerve fibers can take three paths:
- Synapse at the same level they enter the chain
- Synapse at a different level than where they enter the chain
- Exit the chain without synapsing at all
All preganglionic B fibers release _______
Ach! They are all cholinergic!
Why is autonomic innervation of the adrenal medulla unique?
It is innervated only by preganglionic nerve fibers. There’s no synapse until it gets to the chromaffin cells
Name two nonselective alpha antagonists
Phenoxybenzamine
(non-competitive)
Phentolymine
Name two alpha 1 selective antagonists
Doxazosin
Prazosin
What antagonists should be given to someone with pheochromocytoma
A before B always!
Which drugs should be avoided in the patient with pheochromocytoma?
- SNS activating drugs (des, ketamine, pancuronium)
- Ephedrine (nothing to recruit)
- Histamine releasing agents (SAM, morphine)
What effect does SNS stimulation have on K levels?
Serum K will decrease, because epinephrine is stimulating B2 receptors
How long does it take baroreceptors to reset and adapt to a change in BP?
1-2 days
What drugs impair the baroreceptor reflex?
- Volatile anesthetics
- NE
- Propofol
- Beta Blockers
- Ca channel blockers
- ACE inhibitors
- PDE Inhibitors
Activation of the Bezold-Jarisch reflex manifests as:
Bradycardia
Hypotension
Coronary Artery vasodilation
What is the Bainbridge Reflex?
Tachycardia in response to increased volume return
Cushing’s Triad consists of:
Increased ICP
Bradycardia
Hypertension
All postganglionic nerve fibers are _______ fibers
C
What is the post-to-pre ganglion ratio in the PNS?
Roughly 1:1
What is the post-to-pre ganglion ration in the SNS?
Roughly 30:1
Compare SNS and PNS postganglionic fibers
SNS are long
PNS are short
Where are SNS ganglia located?
Near the spinal cord
Where are PNS ganglia located?
Near the effected organ
What vertebral level does the SNS arise from?
Thoracolumbar (T1-L3)
What vertebral level does the PNS arise from?
Craniosacral:
CN 3,7,9,10
S2-S4
