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Why does your cardiac output increase in a warm environment? Is it due to increased blood flow to the skin to dissipate the heat?
Thanks.
Thanks.
Why does your cardiac output increase in a warm environment? Is it due to increased blood flow to the skin to dissipate the heat?
Thanks.
Why does your cardiac output increase in a warm environment? Is it due to increased blood flow to the skin to dissipate the heat?
Thanks.
To clarify:
Increased blood flow to the periphery (as a means to dissipate heat) leads to lowered stroke volume. In order to maintain CO, heart rate will have to be increased--> achieved by net cardiac ANS sympathetic stimulation. Overall CO change will depend on the level of heart rate and stroke volume change.
I had a different take on it.
Peripheral vasodilation to dissipate heat would lead to decreased total peripheral resistance (Poiseuille's equation). In order to maintain blood pressure, cardiac output would have to increase.
The decrease in peripheral resistance leads to a decrease in afterload, so stroke volume would increase. Heart rate would probably also increase in order to maintain blood pressure.
To clarify:
Increased blood flow to the periphery (as a means to dissipate heat) leads to lowered stroke volume...
That sounds correct, SV and HR both increase. Iincreased sympathetic output (decreased inhibition at baroreceptors due to low bp) resulting in increased chrontropy and inotropy at the cardiac level, combined with decreased afterload due to peripheral vasodilation should increase both HR and SV.
Isnt the parasymp system that causes skin blood vessels to vasodilate? An increase in vasodilation of periperhial BVs will lead to a lower TPR and a lowered BP. The lowered BP will signal via the baro-rcs to increase cardiac output via the symp system...?
The response in your skin is locally controlled, just like your muscles get increased blood supply when they are exercising due to a local response. But yes, this leads to a lower TPR (and thus lower afterload)---> in order to maintain BP, your CO is going to increase via symapthetic outflow to your heart (a more central response), driven by baroreceptor reflexes.
Mythbusters did that.Our professor talked about how people go out drinking and die due to hypthermia in certain cold areas..bc alcohol in high doses increases parasymp outflow and causes vasodilation which inappropriate causes heat loss.
Our professor talked about how people go out drinking and die due to hypthermia in certain cold areas..bc alcohol in high doses increases parasymp outflow and causes vasodilation which inappropriate causes heat loss.
I would imagine at the skin it is a combination of parasymp flow and local intrinsic control (hyperemia) that regulates the blood flow to the skin. Either way it is the drop in TPR due to the vasodilation that leads to the increased C.O. to maintain BP.
Do any text books address this?
That sounds correct, SV and HR both increase. Iincreased sympathetic output (decreased inhibition at baroreceptors due to low bp) resulting in increased chrontropy and inotropy at the cardiac level, combined with decreased afterload due to peripheral vasodilation should increase both HR and SV.
Afterload -> This is the load that the heart works against in systole when pumping into the aorta. This is mostly a material property of the aortic wall. This explains why artherosclerosis of aorta leads to increased Systolic pressure (i.e. you develop a higher afterload).