PNS Flashcards
autonomic ns
innervates sm and cardiac muscle
somatic ns
innervates sk
sympathetic response
fight or flight
- increase heart rate/force of contraction
- increase bp: constriction of bv + release of renin
- bronchodilation
- increase blood glucose
- sweat release
parasympathetic response
local effect - rest/digest
- decrease heart rate/force of contraction
- decerease bp
- increase movements of GI/urinary sm
- increased secretion of lacrimal, salivary, mucous glands
- bronchoconstriction
synpase
gap between 2 successive neurons / neuron and target organ
dales principle
each neuron releases a single NT at all its synpase
cotransmission
multiple NT may be released by single neuron
differential release of NT from same neuron =
allows for POSTSYNAPTIC Modulation
how is postganglionic release regulated
presynaptic modulation
homotropic regulation
NT acts on neuron from which it was released
heterotropic regulation
NT acts on a different neuron
autoreceptor
presynaptic receptor binds to NT released by same cell = negative feedback
neurotransmission
nerve impulses (AP) travel down to ganglion = Ca enters neuron
increased Ca promotes exocytosis of vesicles with NT = release into synapse
bind to R
NT is inactivated/removed
cholinergic neurotransmission
acetyl group from acetyl CoA + choline
= choline acetlytransferase
breakdown by AChE: hydrolyzes NT > acetic acid + choline
synthesis of NE
formed from tyrosine
- tyrosin -> DOPA (tyrosine hyroxylase)
- DOPA -> Dopamine (dopamine decarboxlyase)
- Dopamine -> NE (dopamine B-hydroxylase)
uptake of NE
uptake 1: pumped back into postsynaptic cell = monamine oxidase (MAO) // repackaged into vesicles
uptake 2: pumped back into target cell and inactivated by catechol-O-methyl transferase
cholinergic receptors
nicotinic - ganglionic junction
muscarinic - target organs
m2
relaxation of cardiac muscle
adrenergic receptors
a1 + a2 - contraction of
- vascular endothelial cells
- cardiac muscle
- uterine sm
- relaxation of GI
B1 - cardiac muscle contraction
B2 - relaxation of bronchiolar sm
adrenergic and muscarinic receptors
activate G-protein coupled signal GPCRs
m3
increased motility of GI sm
constriction of bronchiolar sm
how can cells that contain the same receptors give different responses to ligand binding
differences in downstream signaling
muscle contraction = Ca entry/release
muscle relaxation = opening of inward rectifying K channel/phosphorylation of myosin heavy chain by PKA
a2 receptors
= autoreceptors = decrease bp
