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Describe short-term regulation of mean arterial pressure (MAP): timing, which pathways, and targets
- Seconds to minutes
- Neural pathways
- Targets heart and blood vessels
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Describe long-term regulation of mean arterial pressure (MAP): timing, which pathways, and targets
- Hours to days
- Endocrine pathways
- Targets kidneys and blood vessels
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Compare sympathetic and parasympathetic innervation of CV system
- Sympathethic chain innervates vessels and heart
- Vagus (parasympathetic) innervates only heart
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How does the CNS control systemic circulation?
- Vasomotor center in brainstem has vasoconstrictor fibers and vasodilator fibers
- Hypothalamus controls the vasomotor center
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What vessels are innervated by the sympathetic nervous system?
Sympathetic innervation to arteries, arterioles, veins, and venules, but not capillaries
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Where are baroreceptors found?
In the walls of large systemic arteries, like carotid and aortic arch
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What are baroreceptors?
Pressoreceptors that detect changes in blood pressure
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How do baroreceptors react to an increase in blood pressure?
Receptors stretch, increase firing rate, and transmit high blood pressure signal to CNS to initiate baroreceptor reflex
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How does the baroreceptor signal get to the CNS? Where in the CNS does it get transmitted to?
- Through the glossopharyngeal and vagus nerves
- To the vasomotor center of the brainstem
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Where is the vasomotor center located specifically?
Medulla and lower third of pons
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What are the parts of the vasomotor center?
- Vasoconstrictor area
- Vasodilator area
- Sensory area
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What do the baroreceptors do after an acute increase or decrease in arterial blood pressure?
Baroreceptors fire more at high blood pressure and less at low blood pressure
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What happens to the vasomotor center if you occlude both carotid arteries?
- Reduction of baroreceptor firing leads to less inhibition on vasomotor center
- Vasomotor center makes blood pressure increase
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If blood pressure increases, what does the baroreceptor reflex do to SNS, PNS, HR, SV, CO, and TPR?
- Want to decrease BP back to normal
- Decreases SNS
- Increases PNS
- Decreases HR
- Decreases SV
- Decreases CO
- Decreases TPR
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If blood pressure decreases, what does the baroreceptor reflex do to SNS, PNS, HR, SV, CO, and TPR?
- Want to increase BP back to normal
- Increases SNS
- Decreases PNS
- Increases HR
- Increases SV
- Increases CO
- Increases TPR
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How does chronic hypertension alter baroreceptor activity?
Desensitized baroreceptors so that they fail to detect elevation of BP and will not respond to decrease it
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What is the baroreceptor reflex in response to hemorrhage?
Less blood = less pressure = less baroreceptor activity = increase SNS = increase BP
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____________________ respond to low O2 and CO2 and H+
Chemoreceptors
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What is the most powerful of all the activators of the sympathetic vasoconstrictor system?
Cerebral ischemia
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How does cerebral ischemia affect the vasomotor center?
Increases sympathetic vasoconstriction to increase BP
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What is the Cushing reflex?
When CSF pressure exceeds arterial pressure, blood flow to brain stops
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How does contraction of skeletal muscles increase cardiac output and arterial pressure?
Increase in flow, increase in BP, increase in CO
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