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95 Cards in this Set
- Front
- Back
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what is responsible for rapid control of arterial blood pressure (seconds to minutes)
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*baroreceptor reflexes
*chemoreceptor reflexes *CNS ischemic response |
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what is responsible for intermediate control of arterial blood pressure (minutes to hours)
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*renin-aniotensin system
*vascular stress-relaxation *cap fluid shift |
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what is responsible for long term control of arterial blood pressure
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renal body fluid mechanisms
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nervous control of the circulation plays a key role in what
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*redistribution of blood flow to various tissues throughout the body
*variations in HR & contractility *producing rapid changes in systemic BP |
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the sympathetic NS has what cardiovascular affects
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*HR
*contractility *peripheral vascular resistance *venous tone *stimuation of renin release |
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the PS nervous system has what cardiovascular effects
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*HR
*limited effect on contractility |
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which has more CV effect sympathetic of parasympathetic NS
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sympathetic
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what is the adrenal medulla
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modified sympathetic ganglion
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what is the 'hallmark" of the SNS
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amplification of response
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sympathetic fibers travel down spinal cord to exit ventral root and then can do one of what 3 things
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1-synapse w/ post-ganglionic neuron
2-travel up or down the chain & synapse w/ post-ganglonic neurons at other levels 3-pass direclty out to collateral ganglion & synapse there |
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sympathetic stimulation of venous system causes what to occur
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*increased venous return
*increased filling pressures *increased CO |
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if you have sympathetic stimulation of arterial side what occurs
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redistribution of that blood flow from that tissue to another tissue by decreasing blood flow there (except in skeletal muscle)
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where are parasympathetic fibers distributed to the heart
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*SA node
*AV node *lesser extent to the atria |
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where in the heart is there LITTLE or NO parasympathetic distribution
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the ventricles
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what is the primary PNS effect in the heart
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CHRONOTROPIC with little effect on contractility
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where are sympathetic fibers distributed in the heart
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*SA and AV node
*atria *ventricles |
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how are sympathetic fibers distributed in the heart
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via the stellate ganglia
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what is the relationship b/t SNS and coronary vessels
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good evidence for SNS regulation of small coronary resistance and larger conductance vessels
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how are parasympathetic fibers distributed to the heart
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via the vagus
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what kind of sympathetic tone is occuring in the heart at all times and why
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BASELINE tone--so there is firing of some sympathetic neurons at all times
-without baseline tone CO falls |
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where is the CNS vasomotor center located
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in the medulla and caudal 1/3 of pons
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how does the CNS vasomotor center transmit parasympathetic impulses to the heart
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via CN X (vagus)
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how does the CNS vasomotor center transmit sympathetic impulses to the heart and blood vessels
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via the spinal cord
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what does the vasoconstrictor area of the CNS vasomotor center do
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excites preganglionic sympathetic vasoconstrictor fibers
(increase sympathetic outflow) |
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what does the vasodilator area of the CNS vasomotor center do
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inhibits activity of the vasoconstrictor area
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what does the sensory area of the CNS vasomotor center do
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receives input from CN IX (glossopharyngeal)and X
-sends output to both the vasoconstrictor & vasodilator areas |
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how is sympathetic vasoconstrictor tone maintained
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by continuous slow firing of impulses from the vasoconstrictor area
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continuous slow firing from the vasoconstrictor area results in what?
this allows for what? |
*results in partial contraction of blood vessels
*allows modulation up or down |
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what is the hormonal feedback loop for BP control
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renin-angiotensin system
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what is the mechanism for vasoconstriction
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*release of NE from postganglionic nerves
*sympathetic stimulation of adrenal medulla |
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release of NE from postganglionic nerve endings causes what to occur
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activation of alpha adrenergic receptors on vascular smooth muscle
(in everything but skeletal muscle) |
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sympathetic stimulation of the adrenal medulla will result in what
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release of NE and epi into the circulation
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in most vascular smooth muscle there is what type of receptor?
activation of this receptor causes what to occur? |
*a1 receptor
*vasoCONSTRICTION |
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in resp, uterine and skeletal smooth muscle there is what type of receptor?
activation of this receptor causes what to occur? |
*b2
*vasoDILATION |
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whether you get vasodilation or vasoconstriction in a tissue is a function of what
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the receptor that is predominant
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sympathetic stimulation in the lungs will cause what to occur
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bronchoDILATION
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vasodilation is controlled by what
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anterior hypothalamus
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vasodilation is thought to be mediated by what
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epi released from vasoDILATOR fibers activating skeletal muscle b2 receptors
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what type of effect does the vasodilation mech have
(major or minor) |
relativey MINOR
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what mechanism is thought to contribute to vasovagal syncope
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vasodilation mech
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the vasodilation mech may allow what type of increase in muscle blood flow prior to local metabolic control
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anticipatory
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rapid increase in BP (5-10sec) depends on what mechanisms
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*arteriolar constriction leading to increased PVR
*venous constriction leading to increased preload & stretch *SNS stimulation of HR and contractility *inhibition of PS vagal outflow |
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BP typically increases how much with heavy exercise
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30-40%
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what are baroreceptors also called
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stretch receptors
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where are baroreceptors located
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widespread throughout large cervical and thoracic arteries
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where are the highest concentrations of baroreceptors(stretch receptors)
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at the carotid bifurcation (carotid sinuses) and aortic arch
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how do baroreceptors(stretch receptors) operate
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by modulating frequency of firing (increase freq of impulses)
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carotid sinus baroreceptor impulses travel via what
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herings nerve to glossopharyngeal nerve then to vasomotor center
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when do carotid sinus baroreceptors begin to fire (work)
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~ 50 mmHg
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aortic arch baroreceptor impulses travel via what
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vagus nerve
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aortic arch baroreceptors begin to fire (work) when
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~ 30 mmHg
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what is the rate of response of baroreceptors
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extremely rapid
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when do baroreceptors have a greater response
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to a rapidly changing BP
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when does the greatest change in impulse frequency occur with baroreceptors
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within the normal range of BP
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activation of stretch receptors results in what
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*inhibition of the vasoconstrictor center
*increased vagal outflow |
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the final result of activation of stretch receptors is what
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*arteriolar and venous dilation
*decreased contractility and HR |
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in EARLY autonomic dysfunction is it PS or sympathetic dysfunction
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PARASYMPATHETIC
-evidenced by HR |
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in LATER autonomic dysfunction is it PS or sympathetic dysfunction
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SYMPATHETIC
-evidenced by BP |
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what in the body is considered the pressure buffer system and why
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*the baroreceptors
*they fxn as a pressure buffer maintaining BP within a narrower range |
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why are barorecptors not as important in LONG term BP control
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d/t to "resetting" of baroreceptors to the new pressure
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when a baroreceptor "resets" when does this occur
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begins within minutes and becomes complete over a period of 1-2 days
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how may baroreceptors produce some LONG term blood pressure control
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through interaction with the renin-aniotension aldosterone system
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where are chemoreceptors located
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*carotid bifurcations(carotid bodies)
*aortic arch(aortic bodies) |
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what do chemoreceptors respond to
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*DECREASED o2
*INCREASED co2 *INCREASED H+ ion |
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how do chemoreceptors transmit impulses
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via
*herings nerve-glossopharyngeal *vagus |
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what effects do chemoreceptors produce
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*excitation of the vasomotor center
*increased resp drive |
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how to chemoreceptors function in relation to baroreceptors
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they are a backup to baroreceptors
-they work at a little bit lower BP |
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where are low-pressure (atrial) receptors located
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*atria
*pulmonary arteries |
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what do low-pressure (atrial) receptors respond to
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changes in VOLUME
(not pressure) |
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what effects to low-pressue (atrial) receptors produce
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responses similar to baroreceptor responses
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what is the volume reflex
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(aka atrial reflex)
atrial stretch d/t increased blood volume |
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what does the volume reflex produce
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*reflex dilation of renal Afferent arterioles
*signaling to hypothalamus to DECREASE adh secretion *INCREASED release of atrial natriutetic peptide |
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what occurs with dilation of Afferent renal arterioles
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increased renal filtration and get rid of more fluid
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what occurs with decreased ADH secretion
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decreased fluid and salt reabsorption
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what occurs with increased release of atrial natriuretic peptide
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increase in fluid loss
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what is the bainbridge reflex
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(aka atrial)
increased right sided filling pressure produces 2 effects on HR 1-DIRECT stretch on SA node 2-stretch receptors located in R atrium & cavoatrial junction are stimulated |
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a direct stretch of SA node results in what
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a 15% increase in HR
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when stretch receptors in R atrium and cavoatrial junction are stimulated what occurs
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*vagal afferent impules travel to medulla w/ subsequent
-decrease in efferent PS activity -increase in SNS activity *results in increased HR and contractility |
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when stretch receptors in R atrium and cavoatrial junction are stimulated how much can HR increase
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40-60%
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what is the CNS ischemic response
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(vasomotor centers are getting ischemic)
dramatic increase in BP in response to a decrease in blood flow to vasomotor center sig enough to impair removal of CO2 |
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the CNS ischemic response produces what effect
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*marked stimulation of the vasoconstrictor & cardioaccelerator neurons
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the CNS ischemic response may produce what type of sympathetic reponse
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a sympathetic discharge severe enough to completely shut down some peripheral vessels (i.e. kidneys)
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what is the cushing reflex
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CNS ischemic response produced by CSF pressure approaching or exceeding arterial pressure and thereby compromising CNS blood flow
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what is the valsalva maneuver
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forced expiration against a closed glottis
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during a valsalva maneuver what occurs
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*increased intrathoracic pressure
*increased CVP *decreased venous return |
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as a result of vasalva maneuver what will happen to CO and BP
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they will fall
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during the valsalva maneuver baroreceptors will do what to HR and contractility
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increase them
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after the valsalva maneuver what happens to HR and contractility
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the opposite--they decrease
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what is the oculocardiac reflex produced by
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*pressure on the globe
*traction on surrounding structures (muscles) |
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what is the pathway for the oculocardiac reflex
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ciliary nerves-->trigeminal nerve-->gasserian ganglion
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what does the oculocardiac reflex result in
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increased parasympathetic and PROUNOUNCED bradycardia
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what is the incidence of the oculocardiac reflex
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30-90% in opthlamic sx
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what is the management of the oculocardiac reflex
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*the reflex will fatigue with repeated epidodes
*antimuscarinics like atropine or glycopyrrolate |
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what is the abdominal compression reflex
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contraction of abd skeleltal muscle following initition of a baroreceptor or chemoreceptor reflex
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what results from the abdominal compression reflex
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compression of the venous reserviors increasing venous return & subsequently cardiac output & BP
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