Unit 2 - Autonomics I Flashcards
length of fibers in the sympathetic division
thoracocolumbar
- preganglionic are short
- postganglionic are long
length of fibers in parasympathetic division
scraniosacral
- preganglionic are long
- postganglionic are short
what are generalizations you can make about:
- all preganglionic
- postganglionic parasympathetic nt
- postganglionic sympathetic nt
- pregang: ALL use ACh to nicotinic receptors
- postgang para: ALL use ACh with little/no branching (1:1 chlinergic fibers) to muscarinic ACh receptors
- postgang symp: NOT ALL use NE with more branching (1:20 adrenergic fibers)
what are the different nt postganglionic sympathetic can use?
- NE to alpha/beta (cardiac and smooth muscle, gland, nerve terminals) –> classical
- ACh to muscarinic (sweat glands)
- D to D1 (renal vascular smooth muscle)
- ACh to neurologic nicotinic (chromaffin cells)
what are skeletal muscle ganglions?
straight from spinal cord via voluntary motor nerve to muscarnic nicotinic ACh
describe ACh
primary nt at ANS ganglia, somatic neuromuscular junction, and at parasympathetic postganglionic nerve endings
- primary excitatory transmitter to smooth muscle and secretory cells in ENS
- major neuron-to-neuron (“ganglionic”) transmitter in ENS
describe norepineNE
primary transmitter at most sympathetic postganglionic nerve endings
how is neurotransmission at cholinergic VS noradrenergic nerve terminals different?
in terms of their handling after release (esp. drugs inhibiting synthesis, storage, and release)
- for ACh, non-specific and not generally useful (except botulinum toxin)
- for NE, specific and useful (b/c release blockers for HTN, uptake blockers, or releasers as stimulants)
what are the best drug targets? why?
target tissue receptors
-allow for selectivity
how do subunit arrangement and molecular structure of nictonic ACh receptors differ?
are all different in regards to muscarinic, neuronal, etc.
are Nn ACh receptors good drug targets? response time?
poor drug targets, but fast responses
are alpha/beta adrenergic receptors good drug targets? response time?
good drug targets, but slow responses to NE (different tissues express different receptors)
are M1-M5 ACh adrenergic receptors good drug targets? response time?
good drug targets, but slow responses (different tissues express different receptors)
what are the steps of response for M1/3/5
Gq –> PLC+ –> DAG increases + IP3 (Ca) increases
like alpha1
what are the steps of response for M2/4
Gi –> AC- –> cAMP (decreases)
Gi –> Kchan+ –> hyperpolarization
(like alpha2)
what are the steps of response for alpha1 adrenergics??
Gq –> PLC+ –> DAG (increase) + IP3 (Ca) increases
like M1/3/5
what are the steps of response for alpha2 adrenergics?
Gi –> AC- –> cAMP (decreases)
Gi –> Kchan+ –> hyperpolarization
(like M2/4)
what are the steps of response for beta1/2/3 adrenergics?
Gs –> AC (increase) –> cAMP (increase)
opposite of M2/4 and alpha2
what are major M1/3/5 effects?
- smooth muscle contraction by M3
- neuroregulation by M1
due to increased IP3 (Ca++) + DAG
what are major M2/4 effects
- slowing of heartbeat and inhibition of nt release due to hyperpolarization
- smooth muscle contraction by opposing cAMP-mediated relaxation due to lower cAMP
what are major alpha1 adrenergic effects?
smooth muscle contraction
due to increased IP3 (Ca++) + DAG
what are major alpha2 adrenergic effects?
inhibition of neurotransmitter release
due to both decreased cAMP and increased hyperpolarization
what are major beta1 adrenergic effects?
increase in force/rate of contraction of heart due to increased cAMP
what are major beta2 adrenergic effects?
smooth muscle relaxation via increased cAMP
what are major beta3 adrenergic effects?
lipolysis via increased cAMP
what are sympathetic VS parasympathetic effects on SA node?
symp: accelerates via beta1/2
para: decelerates via M2
what are sympathetic VS parasympathetic effects on bronchiolar smooth muscle?
symp: relaxes via B2
para: contracts via M3
what are sympathetic VS parasympathetic effects on bladder wall?
symp: relaxes via B2
para: contracts via M3
does NE have a stimulatory or inhibitory effect on alpha2, AII, and M2 receptors?
inhibitory: a2, M2
stimulatory: AII
does ACh have a stimulatory or inhibitory effect on M2 receptors?
inhibit NE release
