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10 Cards in this Set
- Front
- Back
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What are the three types of factors that influence coronary blood flow?
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Physical
Neural and neurohumoral Local metabolic |
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How does the heart autoregulate in abrupt changes in flow?
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When flow increases, pressure initially increases, but then resistance increases to return flow back to normal.
The reverse happens with decreased flow and pressure. At a certain point (above 160 or below 60), this compensatory mechanism does not work. |
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How does blood flow into the left side of the heart function?
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As the pressure on the left side of the heart increases, coronary vessels are closed off, causing a stop in flow. During diastole, the ventricle has less pressure, so blood flows into the vessels.
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How does blood flow into the right side of the heart function?
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The right side of the heart has low pressure, so during systole, blood is pumped into the coronary vessels. The vessels pump most blood during systole.
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How do the sympathetic nerve system and metabolites affect circulation in the heart?
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Increased heart rate and contractility causes vasodilation from production of metabolites, such as adenosine and hypoxia.
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How is cerebral circulation regulated?
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Brain blood flow is dependent on CO2 much more than O2. A drop in CO2 causes an decrease in flow, and an increase in CO2 causes an increase in flow.
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How is cutaneous circulation regulated?
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Functions to maintain constant body temperature.
Sympathetic stimulation causes vasoconstriction of AV anastomosis that shunt blood to the venous plexus. |
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How does cutaneous circulation act to control temperature?
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During cold, sympathetic activation causes constriction of AV shunts to decrease the amount of blood flowing to the venous plexus and capillaries.
During heat, sympathetic activity decreases to increase flow to the plexus and capillaries. |
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How is skeletal muscle circulation regulated?
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During rest, sympathetic innervation causes constriction in arterioles.
During activity, metabolic factors (potassium, lactate and adenosine) reduce tone and promote increased blood flow. |
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How is the splanchnic circulation regulated?
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Functional hyperemia occurs during ingestion of food.
Sympathetic innervation is activated to reduce flow to the GI system and shunt to critical organs. |
