physiology of the ANS Flashcards
motor vs ANS cell bodies
motor - all cell bodies in CNS
ANS - TWO cell bodies - pre and post
how does a synapse work
presynaptic terminal releases vesicles with neuronstransmitters
post synaptic cell has receptors for NT to bind to
types of receptors
inotropic
metabotropic
ionotropic receptors
channel that NT binds - receptor opens to allow ions to go in/out
metabotropic (3) receptors
biochemical effect inside cell
- Gq- inc IP3/DAG - inc Ca2+ released from stores
- Gs- inc adenylyl cyclase - inc cAMP - change phosphorylation in cell
- Gi- dec adenylyl cyclase - dec cAMP
synapse between pre and post ganglionic neurons (SNS vs PSNS)
same between both SNS and PSNS
NT: acetylcholine
receptor: nicotinic cholinergic channel (on dendrites of post ganglionic cells)
result: allows Na+ to enter cell – depolarizes cell (more excitable)- produces action potential
synapse between post ganglionic neurons and target tissue - PSNS
NT: Ach
receptor: muscarinic cholinergic receptor (connected G protein)
M1R, M3R, M5R
bind Gq protein
PSNS receptor for post ganglionic neuron and target tissue
M1R
PSNS
salivary glands, parietal cells of stomach
increases secretion
M3R
PSNS
increase contraction: smooth muscle GI, detrusor wall bladder, ciliary muscle lens
increase secretion: pancreatic secretion
decrease contraction in atria
M2R, M4R
bind Gi protein receptor
PSNS receptor for post ganglionic neuron and target tissue
M2R
SNS
causes efflux of K+–> hyperpolarizes cells –>decreases conduction –> decreases heart rate
dec conduction velocity AV node
inc contraction smooth muscle spinsters GI tract (?)\
dec contraction spinchters in bladder (?)
synapse between post ganglionic neurons and target tissue - SNS
NT: norepinephrine
receptor: adrenergic receptor (alpha, or beta)
alpha 1 receptor
SNS
binds Gq - inc Ca2+
contraction: vascular smooth muscle, GIGU smooth muscle, radial muscle of eye (dilates pupil)
liver: glycogenlysis, gluconeogenesis
adipose tissue: lipolysis
lacrimal: decreased tear secretion
alpha 2 receptor
SNS
binds Gi - dec cAMP
GIGU- sphincters contract
Vascular smooth muscle- relaxes
pancreases - inc glucagon, dec insulin
platelets- more clotting
Beta 1 receptor
SNS
binds Gs - inc cAMP
inc. HR
inc ventricle contractility
salivary - reduced secretion
adipose - lipolysis
Beta 2 receptor
SNS
binds Gs - inc cAMP
relaxation: bronchiole smooth muscle, GI hollow organs, vascular smooth muscle, ciliary muscle, GU muscles
liver - glycogenlysis
how does the ciliary muscle work
contracts- makes lens rounder - see near better
relaxes- makes lens flatter - see far better
Beta 3 receptor
binds Gs
white adipose tissue - lipolysis
brown adipose tissue - heat production
adrenal medulla’s role
adds epinephrine to sympathetic response
chromafin cells
in the adrenal medulla
can synthesize catelcholamines that release epinephrine
presynaptic fibers and the adrenal medulla
special set of cells - do not go synapse sympathetic chain
instead go to the adrenal medulla and synapse ON chromafin cells
what kind of receptors to chromafin cells have
nicotinic cholinergic receptors
open when Ach is released (bc presynaptic cell synapses)
channel opens –> sodium flows in –> chromafin cells depolarize and release epinephrine
