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33 Cards in this Set
- Front
- Back
What is the equation that describes the relationship between Cardiac output and Arterial Pressure:
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MAP = CO x TPR
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Heart rate is altered by what system?
stroke volume is altered by...? |
Autonomic Nervous system
preload afterload contractility |
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the neural reflex system that regulates mean arterial pressure operates as a series of ? feedback loops.
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Negative feedback loops
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Describe the negative feedback loop of the Baroreceptor Reflex.
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Detector stretches --> electrical signal
Affector neural pathway CNS Efferent Neural pathways EFFECTOR |
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Where are High pressure arterial baroreceptors located?
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Internal Carotid Artery
Aortic Arch |
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Where are Low pressure baroreceptors located?
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atria
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Action potentials generated by the carotid sinus and carotid body travel through ? nerve which joins the ? nerve and petrossal ganglion.
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Sinus nerve
joins with GLOSSOPHARYNGEAL CN IX |
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Action potentials generated by the aortic arch and aortic body travel through the ? nerve which joins the ? bodies => inferior ganglion of the vagus
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Vagus nerve (CN X)
joins Superior Laryngeal Bodies |
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Where does positive feedback for parasympathetic preganglionic stimulation occur at?
(baroreceptors) |
Nucleus ambiguus
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Where does negative feedback for sympathetic occur at?
(baroreceptors) |
Vasomotor area
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? receive input from afferent neural pathways and send neural projections via interneurons.
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Nucleus Tractus Solitarius (NTS)
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NTS sends interneurons to what 3 following areas?
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excitatory interneurons to CARDIOINHIBITORY or cardiac decelerator --vagal parasympth cardiac nerves
inhibitory internurons to vasomotor area - sympathetic inhibitory interneurons to cardioacceleratory area - sympathetic |
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True or False
Both Glossopharyngeal Nerve IX and Vagus Nerve X are POSITIVE stimulatory parasymp. and innervate at the Nucleus Tractus Solitarius (NTS) |
True
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Describe the Hypovolemia baroreceptor reflex.
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decrease in circulating volume
=> decrease arterial pressure => decrease stretch of high pressure baroreceptor cause less AP firing => decrease Sinus nerve activity => decrease NTS activity => less inhibition of parasymp ---> more sympathetic nervous activation =>decrease capillary pressure ---> osmotic reabsorption of interstitial fluid |
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What are the three chief determinants of oxygen consumption during contraction?
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heart Rate
Afterload Contractility |
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True or False
Diastolic filling (preload) contributes relatively LITTLE to oxygen consumption. |
True
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MVO2 is highest during?
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isovolumetric contraction/rapid ejection
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MVO2 is lowest during?
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Late diastolic filling
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When is coronary blood flow to the left ventricle is highest in ?
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early diastole
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is myocardial oxygen consumption substantially greater for those conditions that cause pressure overloading?
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Yes it is greater
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Myocardial oxygen consumption can be estimated by calculating the double product of ?
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HR x Systolic BP
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The arteriovenous O2 difference across the ? is the largest for any organ
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coronary vascular bed
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True or False
The heart is an omnivore capable of metabolising a range of substrates, including fatty acids, glucose, ketone bodies, lactate and amino acids to fulfill a continuous demand for ATP |
True
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Majority of ATP is produced via ? in the heart
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Mitochondrial Oxidative Phosphorylation
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True or False
Capillary density in the heart exceeds skeletal capillary density. |
True
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What is the major oxygen carrier in cardiac and skeletal muscle that facilitates O2 from sarcoplasm to mitochondria.
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Myoglobin
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What are the 3 methods of autoregulation?
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local metabolism
endothelium-mediated vasodilation Autonomic nervous System |
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? is a potent vasoconstrictor produced by the vascular endothelium that counteracts many of the actions of nitric oxide.
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Endothelin-1
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Endothelin-1 is released in response to ? and ? and ? to balance the effect of nitric oxide.
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Shear stress
angiotensin II Catecholamines |
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How does endothelin-1 mechanism work?
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=> activates ET-A receptors
=>activate Phospholipase C =>cleaving of PIP2 => IP3 + DAG => ca2+ release VASOCONSTRICTION |
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Tonic sympathetic discharge stimulates ? receptors in the coronary arteries and produces ?
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α1-adrenergic receptors
Vasoconstriction |
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During heavy exercise, an increase in ? coronary vasoconstriction is completely overshadowed by ? that develops as a result of an increase in myocardial metabolism.
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α1-mediated coronary vasoconstriction
vasodilation |
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Vagal stimulation is ? but probably has little direct physiologic effect on the coronary arteries.
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Vasodilatory
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