Hey guys so I'm slightly confused about these 3 things.
From what I understand,
Blood pressure= Cardiac output x Total peripheral resistance
Cardiac output= Stroke volume * Heart rate
Stroke volume depends on 3 things- preload, contractility, and afterload.
When baroreceptors detect a low blood pressure, sympathetic stimulation causes vasoconstriction. This increases total peripheral resistance and afterload. Thereby, it increases blood pressure, but at the same time decreases stroke volume, thereby decreasing cardiac output. Isn't this contradictory?
Also, I'm having trouble understanding the distinction between blood pressure and velocity of flow. If resistance decreases then surely the blood must lose some of its kinetic energy as it has to overcome more resistance- so the velocity of the blood flow should decrease (?), thus exerting a greater pressure on the walls of the arteries. But then don't the tissues get less blood supply? So isn't this mechanism counterintuitive?
And lastly, when we look for a measure of tissue perfusion, do we look at blood pressure or velocity of blood flow? What is the difference between the two?
I appreciate any help you can give me!! Thank you!
From what I understand,
Blood pressure= Cardiac output x Total peripheral resistance
Cardiac output= Stroke volume * Heart rate
Stroke volume depends on 3 things- preload, contractility, and afterload.
When baroreceptors detect a low blood pressure, sympathetic stimulation causes vasoconstriction. This increases total peripheral resistance and afterload. Thereby, it increases blood pressure, but at the same time decreases stroke volume, thereby decreasing cardiac output. Isn't this contradictory?
Also, I'm having trouble understanding the distinction between blood pressure and velocity of flow. If resistance decreases then surely the blood must lose some of its kinetic energy as it has to overcome more resistance- so the velocity of the blood flow should decrease (?), thus exerting a greater pressure on the walls of the arteries. But then don't the tissues get less blood supply? So isn't this mechanism counterintuitive?
And lastly, when we look for a measure of tissue perfusion, do we look at blood pressure or velocity of blood flow? What is the difference between the two?
I appreciate any help you can give me!! Thank you!