Term
| Peripheral Chemoreceptors drive on vasomotor center and cardioinhibitory center |
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Definition
-exert positive drive on vasomotor center and cardio inhibitory center,
-leading to vasoconstriction and decreased heart rate |
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Term
Medullary respiratory center
(role and typical response) |
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Definition
role: integrates input from peripheral chemoreceptors and strongly influences medullary cardiovascular
Response: Fall in PO2, rise in PCO2, or fall in pH
increases firing rate
leading to vasoconstiction and bradycardia
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Term
Location of peripheral chemoreceptors
and how they synapse with medulla |
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Definition
Close to the baroreceptors
carotid bodies-through glossopharyngeal nerve
aortic bodies- through vagus nerve
both synapse with medulla through NTS
So, responses to chemoreceptors overlaps with baroreceptors |
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Term
What is the glomulus cell
and what is it's most important signal affecting it? |
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Definition
-chemosensitive cell in carotid bodies
- low PO2
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Term
Explain why the carotid bodies are in
excellent position to monitor arterial
blood composition |
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Definition
-high blood flow per mass unit
-miniscular arteriovenous differences in PO2, PCO2 and pH |
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Term
| Physiological response to hypoxia and how it differs from what you would expect based on chemoreceptors MOA in CV system |
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Definition
-hypoxia causes tachycardia
- you'd think it would cause bradycardia based on chemoreceptor responose on CV system, but:
- hypoxia stimulates respiratory center (increased ventilation)
-high PCO2 stimulates central chemoreceptors (also increase ventilation)
-Increase ventilation activates pulmonary stretch receptors
-which inhibits cardioinhibitory center
-result is reflex tachycardia |
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Term
Where are central chemoreceptors located
and what do they mainly sense? |
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Definition
-in the medulla
-sense low brain pH (reflects high arterialPCO2)
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Term
What physiological response will occur
when central chemoreceptors sense
low brain pH? |
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Definition
Vasoconstriction
through disinhibition of vasomotor area
causing increase in sympathetic output |
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Term
| What is the principal variable that the CV system controls? |
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Definition
| Systemic mean arterial pressure |
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Term
Physiological significance of systemic mean areterial blood pressure |
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Definition
- all organs have the same blood pressure
(organs control flow by increasing and decreasing arteriole resistance)
-Pressure is constant
(and high enough for glomerular filtration and to overcome high tissue pressure organs)
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Term
| What is responsible for short term regulation of mean arterial pressure? |
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Definition
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Term
| Describe the nerves of aortic arch and carotid sinus baroreceptors |
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Definition
-nerve ends are varicose/coiled and both unmylenated and mylenated
-nerves have non-selective ion channels
-bipolar
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Term
| Describe baroreceptor response to increased pressure/stretch |
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Definition
- stretch causes depolarization
-receptor potential is generated (biphasic)
-receptor potential is transmitted to medulla
-end result is vasodilation and bradycardia |
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