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45 Cards in this Set
- Front
- Back
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Is neural control of the circulation a short term or long term regulatory mechanism?
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Short term regulation
(rapid response) |
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Humoral vasoactive substances exhibit ____________ term regulatory response times.
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Intermediate-long
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What sort of response times do metabolic and endothelial cells have on regulation of vsm?
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rapid to intermediate to long term
|
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What sort of response time does renal control have over arterial pressure?
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Relatively slow
(hours to days) |
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What is the slowest regulatory mechanism of arterial blood pressure?
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Genetic control
|
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What are the 2 primary physiological explanations for autoregulation?
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1. Myogenic effect
2. Local metabolic regulation |
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What is the myogenic effect?
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The stretch of vsm cells causes contraction
|
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What is the local metabolic effect?
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Accumulation of metabolites or low tissue oxygen results in vsm relaxation, increasing blood flow
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What are the 3 types of hyperemia?
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1. Passive hyperemia (congestion)
2. Active hyperemia 3. Reactive hyperemia |
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Which type of hyperemia is the result of increased blood in tissue due to vasodilation or obstruction to flow out of the tissue?
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Passive hyperemia (congestive)
|
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Which type of hyperemia occurs as a result of increased metabolism in tissue?
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Active hyperemia
(Principle of local metabolic control) |
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What causes reactive hyperemia?
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Occurs following an ischemic episode, where initial inadequate flow is followed by increased flow.
|
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What type of control is the major regulator of vascular resistance?
What substances are involved? |
Sympathetic, a-adrenergic, vasoconstriction
Norepinephrine, ATP, NPY |
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Where do pre and postganglionic sympathetic fibers originate?
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Preganglionic fibers originate from the spinal cord from T1 to L3
Postganglionic fibers originate in the sympathetic ganglia |
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What is the action of the parasympathetic NS on arterial pressure?
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(Much less control than sympathetic NS)
Cause vasodilation by the release of ACh and No 1. Salivary glands 2. GI glands 3. Erectile tissue |
|
Where is the vasomotor area located?
|
Within the medullary cardiovascular control center in the rostral ventrolateral medulla
(Origin of sympathetic vasomotor tone) |
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What type of areas does the vasomotor area contain?
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1. Cardiac decelerator area
2. Cardiac accelerator area 3. Vasoconstrictor area |
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Describe the neural flow of the Bulbospinal pathway.
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1. Vasomotor area (medulla)
2. Thoracic spinal cord 3. Preganglionic sympathetic neuron 4. Adrenal medulla |
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At rest, do sympathetic or parasympathetic nerves dominate HR control?
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Parasympathetic
|
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Describe the sympathetic activation of the adrenal medulla.
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Preganglionic sympathetic neurons terminate at the adrenal medulla, releasing ACh which activates chromaffin cells to release Epinephrine, and some NE.
|
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How can circulating ACh indirectly affect vsm?
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ACh can indirectly cause vasodilation via the cGMP second messenger system in endothelial cells.
ACh causes the release of NO, resulting in vasodilation |
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How is sympathetic efferent activity adjusted?
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Baroreceptor reflexes
|
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What do the aortic arch and carotid sinus arterial baroreceptors detect?
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Detect stretch in vessel walls, which is produced by transmural pressure
(mechanoreceptors) |
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Arterial baroreceptors are located next to what other type of receptors?
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Peripheral chemoreceptors
|
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When arterial pressures fall, do baroreceptors increase or decrease their afferent activity?
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Baroreceptors DECREASE their activity when arterial pressures fall.
|
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What is the result of increased arterial pressures above "normal" on the baroreceptor reflex?
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Reflex vasodilation, bradycardia, and decreased stroke volume to lower arterial pressure
|
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What do aortic arch and carotid sinus arterial baroreceptor reflexes regulate?
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1. Arterial pressure
2. Venous compliance 3. Heart rate 4. Cardiac contractility |
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Which of the baroreceptors are more sensitive-- the aortic arch or carotid sinus?
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Carotid sinus baroreceptors are more sensitive
|
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Incoming information to the NTS from peripheral baroreceptors are received by which nerves?
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CN IX and CN X
|
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Once information is received by the Nucleus of Solitary Tract (NST), how is it further transmitted?
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The information is split to cardiac and vasomotor areas:
1. Excitatory information --> cardiac decelerator area, involving nucleus ambiguous and dorsal motor nucleus of vagus end 2. Inhibitory info --> vasomotor area |
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Describe what happens if the input to the NTS is increased.
|
1. Excitatory output from the vasoconstrictor and cardiac accelerator areas is decreased
2. Excitatory output form the cardiac decelerator is increased *Cardiac slowing occurs |
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What are the 2 types of cardiopulmonary baroreceptors?
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1. Ventricular receptors (high pressure)
2. Atrial and pulmonary artery receptors (low pressure) |
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What is the action of ventricular mechanoreceptors?
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Sense high intraventricular pressures and convey info via CN X to vasomotor area--
*Result in reflexive bradycardia and vasodilation |
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Which receptors control the effective circulating volume of blood and cardiac output, therefore, indirectly regulating arterial pressure by affecting venous return to the heart?
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Low pressure baroreceptors
|
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What is the Bainbridge Reflex?
What type of receptors elicit this response? |
A transient tachycardia in response to increased atrial volume
"A type" atrial mechanoreceptors |
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Which type of receptors are low pressure sensors that fire synchronously with atrial systole?
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"A type" atrial mechanoreceptors
|
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Which receptors fire as a burst during ventricular systole, and gradually increase firing during atrial filling?
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"B type" atrial mechanoreceptors
|
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"B type" atrial receptors, when stretched, will cause the heart to release what compound?
What is the function of this compound? |
Atrial Natriuretic Peptide (ANP)
ANP promotes renal excretion of Na+ and water, reducing blood volume--> reducing CVP and atrial pressure |
|
What are the different effects of epinephrine at high and low concentrations?
|
Low concentration --> vasodilation
(beta adrenergic effect) High concentration --> vasocontriction (alpha adrenergic effect) |
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What are the 3 adrenal catecholamins?
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1. Norepinephrine
2. Epinephrine 3. Dopamine |
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What is the affect of arginine vasopressing (AVP) on blood volume?
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Increases blood volume
|
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What is the function of Calcitonin gene related peptide, CGRP?
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Potent vasodilator
|
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On a molar per molar comparison, what is the most potent vasoconstrictor?
|
Endothelin
|
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What is the affect of Atrial Natriuretic Peptide (ANP)?
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Vasodilator
(powerful renal diuresis and natriuresis, reducing BV) |
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What are the effects of kinins on vascular and visceral smooth muscle?
|
RELAX vascular smooth muscle
CONTRACT visceral smooth muscle |
