Ans Physiology and pharmacology the cardiovascular system Flashcards

cardiovascular system
Terms Definitions
the autonomic nervous system affects the cardiovascular system in what four way
chronotropic effect (heart rate), inotropic effect (cardiac contractility), arterial vascular resistance, venous tone (venous capacitance)
define chronotropic effect
heart rate
define inotropic effect
cardiac contractility
define venous tone
venous capacitance/storage
what is the key role of the autonomic nervous system on the cardiovascular function
stay at normal arterial blood pressure
define autonomic reflexes
changes in the ANS activity that occur in response to changes in blood pressure
in the CV system, where is the parasympathetic innervation
the vagus nerve synapse with postganglionic parasympathetic nerves in the wall of atria, interatrial septum near sinoatrial node and atrioventricular nod and on coronary arteries. NOT ventricles.
true or false, PANS innervate the ventricules to decrease contractility
False. there is no PANS innervation in the ventricles so not affect contractility.
for PANS, what receptors and what g protein used?
PANS in heart use M2 muscarinic receptor. The GI protein reduces heart rate and increase PR interval
SA and AV nodes have what kind of PANS receptor
M2 and use GI pathway
what three effects does the receptor activated in PANS play on action potential of pacemakers
PANS use M2 in GI pathway. 1-increaes the IK current so more K so membrane more negative (phase 4). 2- reduce IF (funny Na channels) so less Na ready so slow depolarization. 3-decrease slow inward calcium current ICa that usually make upstroke of action potential in pahse 0 so slower action potential.
what effect to PANS receptors have on atrial muscle contractility
M2 receptor in GI pathway. decreases atrial muscle contractility by decreasing inward calcium current and decreasing CAMP production.
how do PANS and SANS oppose each other at the g protein level
PANS is GI and M2 receptor. SANS is GS using cAMP method and beta receptor. GI stops adenylyl cyclase so no cAMP.
how do the receptors for PANS behave like heteroreceptors
the M2 receptors also expressed in postganglionic SANS nerves to inhibit norepinephrine release. so M2 binds Ach to inhibit NE. similar to role of alpha 2 found at PREganglionic nerve.
define heteroreceptor
a receptor that is activated by a neurotransmitter that is not the neurotransmitter that spews out of the synapse.
how do the receptors for PANS act like autoreceptors
M2 receptors located on postganglionic PANS nerves bind Ach to inhibit Ach
where are M3 receptors
M3 receptors are on endothelial cells of vessels.
what is the role of M3 receptors? what g protein function?
M3 receptors in endothelial cells of walls of vessels. Make nitric oxide synthase for NO. use GQ pathway making phospholipase C-IP3-calmodulin pathway.
define endothelium derived relaxing factor
nitric oxide from M3 receptors on walls of vessels
how does nitric oxide function in the cell
makes cGMP that dephosphorylate myosin light chain kinase and so muscle relaxes.
what nerves innervate the M3 receptors
how does atropine work in heart
atropine increases heart rate by stopping PANS normal tone.
what happens in synaptic bulb of SANS nerve? synthesis, storage, clearance?
amino acid tyrosine makes dopamine, norepi and epinephrine. vesicular monoamine tranporter take the neurotransmitter to synaptic vesicles like a shuttle. cleared by reuptake, recycled by monoamine oxidase in mitochondria, recycled by catecholamine-o-methyltransferase in synaptic gap.
what organ also has lots of monoamine oxidase
liver. to chew up things that could potentially act like sympathetic stimulant.
give examples of substances that inhibit reuptake of SANS neurotransmitters
serotonin-selective reuptake inhibitor antidepresants and cocaine.
what are the autoreceptors for SANS
alpha 2 located on PREganglionic SANS nerves to stop norepinephrine release
what is the function of alpha receptors on smooth muscle
constrict/contract. ALWAYS
what is effect of beta 2 receptors on smooth muscle
dilate ALL smooth muscle EXCEPT in the heart
for heart, what function of:
beta 1
beta 2
beta 1 and beta 2 increase heart rate and contractility
in vessels what function of alpha
in vessels what function of beta 2
vasodilate ALWAYS ESCEPT for cardiac muscle vessels
what three effects does the receptor activated in SANS play on action potential of pacemakers
beta receptors for SANS. increase slow inward calcium current pase 0 upstroke of action potential so that increase heart rate. 2-increase the IF current (funny sodium channel) making more negative so that can have depolarization in phase 4. 3-sequester Ca faster so shorten action potential length and refractory period
how does SANS increase contractility
increase the Ca influx. increase sequesteration for faster relaxation and ready to contract again.
how does constriction work for vessels when have SANS activation
alpha receptors simulated by SANS so vasoconstrit. reduce diameter increase resistance. increase afterload and BP.
why does SANS constrict and also dilate
SANS constrict and dilate vessels to make optimal redistribution of blood to organs
describe how SANS in charge of dilation
to optimally redistribute blood to organs. beta 2 vasodilate vessels when get epinephrine from adrenal medulla.
what receptors activated:
epinephrine alpha 1=alpha2 and beta 1=beta 2.
norepinephrine alpha1=alpha2
ONLY beta 1
what is postural hypotension and how occur?
no vascular response to SANS activation. patient taking drugs to block alpha constrictors. syncope
what is role of hormones in maintaining blood pressure
baroreceptors in juxtoglomerular apparatus of kidney sense low blood pressure and make renin and eventually aldosterone.
describe pathway to aldosterone
baroreceptors in juxtoglomerular apparatus of kidney tell cells make renin, angiotensin, angiotensin I, angiotensin II, aldosterone from adrenal cortex.
what is functionof aldosterone
when low blood pressure, aldosterone stops excretion of water to maintain blood volume.
what happen when inject Ach?
Ach is PANS so normall slow heart rate. IV Ach increase heart rate reflex response uninnervated M3 in vessels release nitric oxide relaxers. baroreceptors kick in and turn on SANS
what happen when inject norepinephrine
norepinephrine is SANS normal effect increase heart rate. IV norepinephrine debrease heart rate. when NE bind alpha increases BP B1 increase contractility. baroreceptors kick in and turn on PANS.
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