Describe short-term regulation of mean arterial pressure (MAP): timing, which pathways, and targets
- Seconds to minutes
- Neural pathways
- Targets heart and blood vessels
Describe long-term regulation of mean arterial pressure (MAP): timing, which pathways, and targets
- Hours to days
- Endocrine pathways
- Targets kidneys and blood vessels
Compare sympathetic and parasympathetic innervation of CV system
- Sympathethic chain innervates vessels and heart
- Vagus (parasympathetic) innervates only heart
How does the CNS control systemic circulation?
- Vasomotor center in brainstem has vasoconstrictor fibers and vasodilator fibers
- Hypothalamus controls the vasomotor center
What vessels are innervated by the sympathetic nervous system?
Sympathetic innervation to arteries, arterioles, veins, and venules, but not capillaries
Where are baroreceptors found?
In the walls of large systemic arteries, like carotid and aortic arch
What are baroreceptors?
Pressoreceptors that detect changes in blood pressure
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
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
Where is the vasomotor center located specifically?
Medulla and lower third of pons
What are the parts of the vasomotor center?
- Vasoconstrictor area
- Vasodilator area
- Sensory area
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
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
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
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
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
What is the baroreceptor reflex in response to hemorrhage?
Less blood = less pressure = less baroreceptor activity = increase SNS = increase BP
____________________ respond to low O2 and CO2 and H+
What is the most powerful of all the activators of the sympathetic vasoconstrictor system?
How does cerebral ischemia affect the vasomotor center?
Increases sympathetic vasoconstriction to increase BP
What is the Cushing reflex?
When CSF pressure exceeds arterial pressure, blood flow to brain stops
How does contraction of skeletal muscles increase cardiac output and arterial pressure?
Increase in flow, increase in BP, increase in CO