1-ANS Flashcards
autonomic nervous system
definiton
portion of nervous system that controls most visceral functions and accomodates coordinated responses to external stimuli
and internal, involuntary, multiple inputs being balanced
cardiovascular
primary chronic autonmic failure
orthostatis hypotension
sudomotor
primary chronic autonmic failure
anhidrosis
heat intolerance
renal/urinary bladder
primary chronic autonmic failure
nocturia
inc frequency, urgency
incontinence
urine retention
gastrointestinal
primary chronic autonmic failure
constipation, diarrhea sometimes, dysphagia
reproductive
primary chronic autonmic failure
erectile/ejaculatory failure
neurologic
primary chronic autonmic failure
parkinsonian
cerebellar/pyramidal features
respiratory
primary chronic autonmic failure
stridor
inspiratory gasps
apenic episodes
respiratory
primary chronic autonmic failure
stridor
inspiratory gasps
apenic episodes
parasympathetic pathway
- CNS
- pre-ganglionic fiber
- neurotrans Ach
- nicotinic receptor on parasympathetic ganglion
- parasymp post ganglionic fiber
- neurotrans Ach
- muscarinic receptors
sympathetic pathway
- CNS
- pre ganglionic fiber
- Ach
- nicotinic receptor on sympathetic ganglion or adrenal medulla
- sympathetic post ganglion fiber
- norepinephrine
- adrenergic receptors
post gang fiber longer than parasymp
modes of innervation
sympathetic
preganglionic neruon
1. paravertebral ganglia/prevertebral > post gang neuron
2. specialized ganglia - superior cervical, celiac, superior mesentaric, inferior mesentaric > target organs
3. adrenal medulla
thoracolumbar
parasympathetic outflow
- cranial- oculomotor N, facial N, glossopharyngeal N, vagal N - ganglia close to target
- sacral- bladder, descending colon, rectum, genitalia
enteric nervous system
system of ganglia b/t layers of the gut and connected by dense meshwork of nerve fibers
-input from both symp and parasymp
has myenteric plexus for motility and submucosal plexus for ion/fluid transport
dual innervation of autonomics
-most organs receive both SANS and PANS innervation so actions controlled by both systems
EXCEPT organs for sympathetic only
sympathetic only organs
- hair follicles
- thermoregulatory sweat glands
- liver
- adrenal gland
- kidney
cholinergic neurotransmission
synthesis
- uptake of choline by choline transporter into presynaptic terminal
- conjugation with acteylCoA
- syn of Ach by ChAT
uptake blocked by hemicholiniums
cholinergic storage
packed into vesicle by VAT
can be blocked by vesamicol so no storage
cholinergic release
- depolarization nerve terminal
- voltage dependent Ca entry
- Ca-calmodulin binds with VAMP and SNAP to trigger fusion
- exocytosis
fusion blocked by botulinum toxin botox
cholinergic termination of action
- rapid hydrolysis of Ach by AchE
- form choline and acetate
- re-uptake into terminals
cholinergic receptors
- nicotinic - Na ion channels, alpha subunit binds Ach to open
- muscarinic- G protein coupled with subtypes M1-5
nicotinic receptor activation responses
- adrenal medulla = secretion of epinephrine and norepine
- autonomic ganglia = stimulation dependent on PANS/SANS
- neuromuscular junction = twitch/hyperactivity of skeletal muscle
M1/3/5
use Gq/G11 receptors
inc Ca and PKC
M2/4
use Gi/Go receptors
dec cAMP
receptors @ eye
- muscarininc = M3 in ciliary muscle and sphincter muscle
- adrenergic = alpha 1 in dilator muscle, alpha 2 + beta 1 and 2 in ciliary body, beta 2 in ciliary muscle
M3 in the eye
M3 stimulated = contraction of sphincter> leads to miosis and open of schlemm canal, contraction of ciliary muscle > spasm accomodation (near vision)
M3 inhibited = mydriasis, paralysis of accomodation to near vision
GI tract
muscarinic
stomach = M3 > inc motility, cramps
glands = M1, M3 > secretion
intestine = M3 > contraction, diarrhea, involuntary defacation
in Ca
bladder
muscarinic receptors
M3 = contraction of detrusor, relaxation of trigone/sphincter, voiding, urinary incontinence, inhibit external sphincter
inc Ca and PKC
lungs
muscarinic receptors
bronchioles = M3 > contraction/bronchospasm
glands = M3 > secretion
inc Ca and PKC
heart
muscarinic receptors
SA node = M2 > bradycardia
AV node = M2 > dec conduction velocity, dec ventricular contraction
atrial muscle = M2 > dec atrial contraction
ventricular muscle = M2 > dec ventricular contraction weakly
dec cAMP
CNS
muscarinic receptor
M1,3,5 = excitement, severe convulsion and coma
lacrimal gland
muscarinic recpetor
M3 = lacrimation
sweat and saliva glands
M3= secretion of sweat and salivation, thermoregulatory
sphincters
muscarinic
M3= relaxation
EXCEPT lower esophageal and eye
inc Ca and PKC, release NO
blood vessels
muscarinic receptors
M3 = vasodilation via NO if endothelium intact
if endothelium damaged then activate smooth muscle M3 = vasoconstriction
ciliary muscle
receptors
M3 = contraction
B2= relaxation
transmission in the heart
- Ach released from post gang cholinergic axon
- M2R linked by Gi to K channel = hyperpolarization
- voltage dependent opening of pacemaker Na channel
- phosphorylation of LTCC
control of detrusor tone
indirect stimulation:
Ach > M2 > dec cAMP > reduce relaxation by NE induced beta activation (aka uno reverse beta stim)
direct:
Ach > M3 > IP3 > ER Ca release > store operated Ca entry > contraction
control of vascular tone
dual control by perivascular nerves and endothelial cells aka
nerve terminal secretions + endothelial secretions
severe responses muscarinic activation
DUMB BELSS
GI = diarrhea
bladder = urinary incontinence
eye = miosis
lung = bronchospasm
heart = bradycardia
CNS = excitement
L = lacrimation
glands = sweat
sphincters = relaxation
vessels = vasodilation
catecholamine synthesis pathway
- tyrosine > DOPA via tyosine hydoxylase, blocked by metryosine
- DOPA > dopamine
- dopamine > norepinephrine @ storage vesicle via VMAT, blocked by reserprine
- norepinephrine > epinephrine @ adrenal medulla only
- VAMPs stimulate fusion, blocked by betylium
- exocytosis
- termination- diffusion, autoreceptor dec release, reuptake via NET1
alpha-1 activation
inc Ca and PKC
Gq + phospholipase C (IP3 and DAG)
beta adrenergic receptors
activation
inc cAMP and PJA
Gs > adenylate cyclase
alpha-2 activation
dec cAMP
Gi > adenylate cyclase
alpha-1 activation effects
eye = radial/dilator muscle contration > mydriasis
arterioles = contraction, inc TPR, inc afterload
veins = contraction, inc return, inc preload
liver = inc glycogenolysis, inc blood glucose
male sex = ejaculation
bladder = constriction of trigone/internal sphincter, urinary retention
alpha-2 activation
prejunctional nerve terminal = dec transmitter release, dec NE synthesis
platelets = aggregation
pancreas = dec insulin secretion
beta-1 activation
heart = inc heart rate (SA) + inc conduction velocity (AV) + inc force contraction + inc velocity rate + inc cardiac output + oxygen consumption
kidney = inc renin release
beta-2 activation
vessels = vasodilation, dec BP
uterus = relaxation
bronchioles = dilation
skeletal muscle = inc glycogenolysis contractility
liver = inc glycogenolysis
pancreas = inc insulin secretion
D1 activation
@renal, mesenteric, coronary vessels = vasodilation, inc glomerular filtration, inc renal blood flow, inc Na excretion
homotropic interactions
aka negative feedback
transmitter binds presynaptic autoreceptors to block release by dec cAMP
either alpha-2 for adrenergic presyn or M2 for cholinergic presyn
heterotropic interactions
one neurotrans affects release of another aka norepine (alpha-2 adrenergic) inhibits Ach (M2 cholinergic) to dec cAMP
coordinates PANS and SANS
denervation supersensitivity
if cut a nerve then supersensitive downstream or if remove a blocker from target organs
bc proliferation of receptors or loss of mechanisms for removal of trans
rebound hypertension after withdrawal of adrenocepttor blockers
cotransmission
neurons release more than one trans
modifies response of effector to primary trans or act on autoreceptor to modulate release
more diverse physioloical control to direction control mechanisms
feedback loop of arterial blood pressure
pathway
- inc BP
- baroreceptor discharge
- activate vasomotor center
- SANS dec sympathetic tone so dec vasoconstriction, contractions, and heart rate
- PANS inc vagal tone so dec heart rate
- dec BP
arterial BP with TPR
inc total peripheral resistance by stim alpha-1 = reflex bradycardia (dec HR)
dec total peripheral resistance (dec alpha-1) = reflex tachycardia
feedback loop BP
hormonal
- dec BP
- dec renal blood flow
- inc renin production
- inc angiotensin
- inc aldosterone
- inc blood volume
- inc cardiac output
- inc BP
OR
1. dec BP
2. inc sympathetic drive
3. inc TPR
4. inc BP
