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21 Cards in this Set
- Front
- Back
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carotid sinus baroreceptors respond to pressures of what range?
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60-180 mmHg
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Carotid sinus receptors are most influential. Innervation is via Herring’s nerve to the ____________ nerve to the tractus solitarius.
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glossopharyngeal
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Does venous constriction increase TPR?
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no,
Vasoconstriction increases heart and arterial volumes |
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Pathway of reflex:
a. Stimulation of receptor b. ___________???? c. Inhibition of the vasomotor center d. Excitation of the vagal center e. Vasodilation of arterioles and veins and decrease in heart rate and contractility. |
Tractitus solitarius
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Chemoreceptors are sensitive to O2 lack, CO2 excess, or ____ion excess.
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H
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Where are the chemoreceptors?
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carotid bodies and on aortic arch and in brain
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Does activation of the chemoreceptors result in EXCITATION or RELAXATION of the vasomotor center.
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Excitation
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Chemoreceptor reflex is not powerful until pressure is what?
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below 80 mmHg
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What reflex is this:
Increased atrial pressure causes increased heart rate. |
Bainbridge reflex
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Reduced cerebral blood flow causes buildup of what dissolved gas?
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CO2
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What happens if the brain has CO2 buildup?
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vasomotr center is stimulated --> arterial pressure is increased
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CO2 buildup in the brain causes stim of SNS and increased BP. How do you explain vasodilation in the brain?
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CO2 --> carbonic acid --> H+ ions --> linear relationship with dilation (up to 2X blood flow)
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At what pressures is the CNS ischemic relfex important?
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only when pressure drops below 60 mmHg with the most powerful response at pressures of 15 to 20 mmHg. Thus this reflex is not normally important.
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What is the Cushing Reaction?
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a response to increased cranial pressure that causes ischemia through arterial compression.
a special type of CNS ischemic response that results from increased pressure of the cerebrospinal fluid around the brain in the cranial vault. |
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How long can the CNS ischemic reflex last?
How high can it make the pressure? |
Can last as long as 10 minutes and increase pressure to 250mmHg+.
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Which is more important?
a) Bainbridge reflex b) SA node stretch reflex |
Both are equally important (says Matayoshi)
Guyton: An increase in atrial pressure also causes an increase in heart rate, sometimes increasing the heart rate as much as 75 per cent. A small part of this increase is caused by a direct effect of the increased atrial volume to stretch the sinus node: it was pointed out in Chapter 10 that such direct stretch can increase the heart rate as much as 15 per cent. An additional 40 to 60 per cent increase in rate is caused by a nervous reflex called the Bainbridge reflex. |
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which nerve carries the Bainbridge reflex?
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signal is via vagus and returns through vagus and SNS
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the major determinant of extra-cellular fluid volume
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Na+
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angiotensinogen comes from where?
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liver
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where is Renin synthesized and stored?
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JG cells, which are modified smooth muscle cells in afferent arterioles of the kidney
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What causes vasoconstriction of the afferent arteriole and an even greater vasoconstriction of the efferent arteriole increasing GFR but also increasing the filtered fraction?
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Angiotensin II
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