Autonomics Flashcards
somatic nerve basics
1 neuron
Ach to effector neuron
parasympathetic basics
2 neurons
first is longer
Ach at ganglion and effector organ
sympathetic neuron basics
2 neurons - Ach between NE at effector organ
neurons same length
adrenal medulla - 1 short neurone and NE and others to organ
symathetic origin and ganglia
origin: thoracolumbar
ganglia: close to CNS
parasympathetic origin and ganglia
craniosacral
gang: close to effector neuron
autonomic eyes
p: constricts
s: dilates
autonomic tears
p: stim
salivary flow autonomic
p: stim
s: inhib
heart autonomic
p: slows
s: speeds
arterioles autonomic
p: dilate
s: consrict
bronchi autonomic
p: constrict
s: dilate
bladder autonomic
p: consticts
s: relaxes
gut autonomic
p: digestion and mobilitiy
s: inhibits
parasympathetic innervation of the heart
right vagus - SA node
left vagus - AV node
vagal efferents - atrial muscle
NO VENTRICLE
synathetic innervation of the heart
sympathetic efferents - SA, AV, atrium, ventricle
division of the autonomic nervus system
cholinergic: nicotinic and muscarinic (sensitive to Ach)
adrenergic: alpha and beta (sensitive to adrenline - epi and NE)
not the same as sym/para
vagus nerve espieriment
2 hearts: one w vagus nerve stim, one without
both hearts in saline
stimulated vagus nerve for 1 - HR slowed
removed saline from heart 1 nd applied to 2
2 slowed
later proven to be Ach
which neurons are cholinergic?
- all pre-ganglionic neurons
- all parasympathetic post-ganglionic
- sympathetic poast-ganglionic that innervate sweat glands
divisions of chonlinergic receptors?
nicotinic
muscarinic
where are nicotonic receptors?
cholinergic!
skeletal muscle end plate
all auntnomic ganglia
adrenal medulla
curare
antagonist for nicotinic receptors
what will happen if block nicotinic receptors?
inhibit both sympathetic and parasympatehttic tone
need to know what tone is dominiant to know clinical effect
i. e. vascular SM has only sympathetic innervation! if there is an agonist, there will be vasoconstriction, antagonist - vasodilation
i. e. male sexual response is sym and para sym so blockers affect ejaculation and erection
nicotonic receptor mechanosim
Na/K ion channel (NOT G-protien)
where are muscarinic receptors
cholinergic!
all parasympathetic effector organs (heart, gi, bronchioles, bladder)
some sympathteic (sweat glands)
types of muscarinic receptors
M1 - ganglia
M2 - heart
M3 - glands, sm
mechanism of muscarinic receptors
similar to alpha 1 - PLC
muscarinic receptors in the SA node
when stim by Ach lead to GPCR activation nd lead to opening of K channels which slows rate of depolarization (slower heart rate)
M1
ganglia
M2
heart
M3
glands
non-selective cholinergic blocker for muscarinic
i.e. atropine
blocks MUSCARINIC receptor in target tissue
blocks all parasympathetic tone!
leads to sympathetic side effects (fast HR< dry mounth, pupil dilation)
types of adreneric receptor
aplha and beta
alpha agonist
adrenergic!
in general, mediate smooth muscle contraction
alpha 1 receptors
vascular smooth muscle
NO cAMP
agonist –> PLC (via GPCR) –> IP3 –> increased Ca
i.e. pubil dilation and smooth muscle contraction
alpha-2 receptors
less common than alpha 1 (adrenergic)
mostly presyn-terminals, platelets, walls of GI
DECREASE cAMP (i.e. GI relaxation
beta agonist
adrenergic
in general - mediate decreased smooth muscle contraction (bronchodilation, vasodilation, uterine relaxation)
BUT in heart - stimulation causes increased HR, strength of contractions
beta-1 receptor
adrenergic
high numbers in heart (SA, AV, ventricle), salivary glands, adipose
increase in cAMP (through G protein)
agonist in heart - increaset HR, contractility
agnoist in kidney - increase renin secretion (increase BP)
beta-2 receptor
in vascular smooth muscle of skeletal muscle, GI, bladder, bronchioles
increase in cAMP - GPCR
agonist –> SM dilation (bronchodilation in asthma)
beta 3 receptor
found in fat
reg lipolysis and thermogenesis
beta and alpha 2 receptors
same mechanism BUT beta increases cAMP to have effect and alpha-2 decreases cAMP to have effect
affects of cAMP in myocytes and blood vessels
myocyte - cAMP increases contraction via stim of PKA (beta1)
blood vessels - cAMP decreases contraction by inhibition of MLCK (beta-2)
downstream affect of cAMP is different
if a patient has used cocaine that stim both alpha and beta, a beta blocker can’t be used, why?
leads to unopposed alpha agonism and severe hypertension
dopamine
precursor to NE - mkes a lot of diff things from tyrosine
diff effects at diff concentrations
pupil innervation
radial muscle: alpha1 - sympathetic tone dilates pupils
circular sphintor - muscarinic - parasypathetic contracts pupil (near vision)
ciliary muscle -
beta - sym tone dilates (far vision)
M receptors - para sym contracts (near vision)
SA node innervation
B1 + M receptors
increase sym tone - increase HR
decrease sym tone - decrease HR
if decrease BP - stim B1/inhib M - tachycardia - compensates for the loss of stroke volume
bladder autonomic innervation
filling - sympathetic - relax detrusor and contract internal sphincter
empty - parasympathetic - contract detrusor and relax internal sphincter
