NS IV Autonomic Nervous System Flashcards
what are the NT of the SNS
Norepinephrine and epinephrine
what are the NT of the PNS
AcH
where are the preganglionic neurons of the SNS located
in the lateral gray horn of the spinal cord
where are the preganglionic neurons of the PNS located
motor nuclei of cranial nerves 3,7 ,9 and 11
what do ALL preganglionic terminals release and where does it bind
AcH that binds to nicotinic receptors on the postganglionic neuron
what type of receptors are nicotinic acetylcholine receptors and what are they selective for
ligand gated ion channels (ionotropic) selective for Na+ and K+
where are postganglionic neurons located
outside the CNS
what are the options of pathways sympathetic fibers will follow after exiting through a white ramus into one of the ganglia of the sympathetic chain
-synapse with postganglionic neurons at that ganglia
- pass up or down the sympathetic chain then synapse with a different ganglia
- pass through the chain and out a sympathetic splanchnic nerve where it will synapse in a peripheral sympathetic ganglion
what receptor types does NE activate
alpha and beta receptors
what do most sympathetic postganglionic terminals release and what is the exception
norepinephrine except at sweat glands they release AcH to activate muscarinic receptors
what does the adrenal medulla secrete when activated and what does it do
80% epinephrine and 20% norepinephrine into the blood stream to activate adrenergic receptors
what enzyme does the adrenal medulla contain and what does it do
PNMT which catalyzes the conversion of NE to EPI
which receptor has a lower affinity for catecholamines: alpha or beta
alpha
which has a greater potency at alpha receptors: NE or EPI
NE
what does alpha 1 receptors do
constrict smooth muscle
what do alpha 2 receptors do
blocks further NE release
which has a higher potency at beta 1 receptors: NE or EPI
almost equal
which has a higher potency at beta 2 receptors: NE or EPI
EPI- much higher
which has a higher potency at beta 3 receptors: NE or EPI
NE slightly greater
what do beta 1 receptors do
increase heart rate and contractility, increase lipolysis, increase renin secretion, increase protein content in saliva
what do beta 2 receptors do
relax smooth muscle, release FA and glucose
where are beta 3 receptors foun
adipose tissue
where are alpha 1 receptors found
effector tissues, smooth muscle, glands
where are alpha 2 receptors found
nerve endings, some smooth muscle
where are beta 1 receptors found
cardiac muscle
where are beta 2 receptors found
smooth muscle, liver, heart
where are beta 3 receptors found
adipose cells
what is the effect of injection of epinephrine
causes vasoconstriction via alpha 1 receptors at the site of administration which decreases blood absorption and facilitates neuronal uptake, enhances the quality of analgesia, prolongs duration of action, and limits toxic side effects
what does albuterol do
causes bronchodilation through beta 2
what are the ways that NE can be removed from the synapse
-diffusion away from synaptic cleft
- reuptake by presynaptic terminal
-destruction by the enzyme monoamine oxidase (MAO) or COMT
what is the difference in axon length between SNS and PNS
PNS has longer preganglionic axons
what do preganglionic axons of the PNS supply
-face via CN 3,7,and 9 and the thorax and upper abdomen via CN 10
- pelvic viscera
what are the actions of the PNS via muscarinic receptors
-Digestion
-Urination
-Miosis
-Bronchoconstriction
- Bradycardia
-Lacrimation
-salivation
what type of receptors are muscarinic receptors
GPCRs
what do muscarinic receptors do
constrict smooth muscle, relax sphincters, stimulate glandular secretions
where are M1 receptors located and what is their effect
-stomach and salivary glands
-excitatory
where are M2 receptors found and what is their effect
- smooth muscle, myocardium, cardiac autorhythmic cells, CNS
-inhibitory
where are M3 receptors found and what is their effect
-exocrine glands, smooth muscle, endothelium, sweat glands
-excitatory
where are M4 receptors found and what is their effect
-CNS, vagal nerve
-inhibitory
where are M5 receptors found and what is their effect
-CNS
-excitatory
what can cause sialorrhea (drooling) in patients
anti-cholinesterases
what does the PNS do in the bladder? SNS?
PNS: M2 relaxes sphincter, M3 constricts detrusor
CNS: alpha 1 contricts sphincter, beta 2 relaxes detrusor
what does the PNS do in the GI tract? SNS?
PNS: M2 relax sphincter, M3 contracts muscle
SNS: alpha 1 constricts sphincter, Beta 2 relaxes muscle
what does the PNS do in the salivary glands? SNS?
PNS: M1 and M3 stimulate watery secretion due to contraction of myoepithelial cells and vasodilation
SNS: alpha 1 vasoconstriction and secretion of concentrated saliva, beta 1 receptors stimulate secretion of protein
what is the effect of the SNS on vascular smooth muscle/ blood vessels
alpha 1: vasoconstriction
beta 2: vasodilation
what is the effect of the PNS on the lungs? SNS?
PNS: M3 constricts bronchial smooth muscle
SNS: beta 2 relaxes bronchial smooth muscle
