Autonomic nervous system Flashcards
Indirect-acting sympthomimetics example (1) depend on norepinephrine release to be effective.
Ephedrine
Preganglionic neurons stimulate nicotinic cholinergic
postganglionic neurons by releasing?
Acetylcholine
Postganglionic adrenergic neurons synapse at targeted end-organs and release?
Norepinephrine
Paravertebral ganglia are found in the (4)?
- Cervical
- Thoracic
- Lumbar
- Pelvic sympathetic trunks
Prevertebral ganglia are named in relation to?
Major branches of the aorta
What are the prevertebral ganglia?
- Celiac
- Superior & inferior mesenteric
- Renal
4 examples of postganglionic adrenergic receptors
a1, a2, b1, b2
Postganglionic (postsynaptic) receptors? (3)
a1, a2, b2
Postganglionic (presynaptic)
a2
Stimulation of a2 inhibits release of what?
Norepinephrine
Both preganglionic and postganglionic PARASYMPATHETIC neurons release?
Acetylcholine
These are are hydroxy-substituted phenylethylamines and stimulate adrenergic nerve endings.
Catecholamines
Naturally occurring catecholamines (3)
Epi, norepi, dopa
Synthetic catecholamines (2)
1) Dobutamine
2) Isoproterenol
What process is the most important mechanism and allows reuse of the neurotransmitter norepinephrine.
Reuptake
Is a prototypical selective a1-blocker
Prazosin
Examples of nonselective a-blockers
Phentolamine and phenoxybenzamine
It is a nonselective b-blocker which also has selective
a1-blocking properties and is a potent antihypertensive
Labetalol
Also known as anticholinergics
Muscarinic antagonists
How might you tell if a patient has autonomic dysfunction?
If the autonomic nervous system is intact, an increase in
heart rate of 15 beats/min and an increase of 10 mm Hg in DIASTOLIC blood pressure are expected when changing position from supine to sitting.
Autonomic dysfunction is suggested whenever there is a loss of heart rate variability, whatever the circumstances.
Preanesthetic management of patients with pheochromocytoma
a-blockade and rehydration
Drug used in pheochromocytoma
Phenoxybenzamine
Nice to know
b-Blockers are often administered once a-blockade is achieved and should never be given first because
unopposed a1-vasoconstriction results in severe, refractory hypertension.
b-blocker of choice in pheochromocytoma
Labetalol