Peripheral resistance and blood pressure Flashcards
What is the equation for mean arterial pressure?
Cardiac output x total peripheral resistance.
What is the cardiac output cardiac?
Heart rate x stroke volume.
What is blood flow proportional to?
The pressure gradient and inversely proportional to the resistance.
What is Poiseuille’s law?
The idea that flow is directly proportional to the pressure gradient vessel and the radius^4 of the tube, and inversely proportional to the length of the vessel and to the viscosity of the fluid.
What is the equation for blood flow?
Change in pressure (pressure gradient)/resistance.
What is flow equal to?
The cardiac output in L/min.
What is the pressure gradient equal to?
Blood pressure in mmHg.
What is resistance equal to?
Peripheral resistance.
What is the equation for cardiac output?
Blood pressure/peripheral resistance.
In what direction does blood flow always occur?
From areas of high pressure to areas of low pressure.
What does a longer tube result in?
More resistance and therefore less flow. This remains constant and therefore does not control blood flow.
What does a higher viscosity result in?
More resistance and therefore less flow. It is related to the hematocrit (red bood cells) and is dependent on dehydration, high altitude and erythropoietin.
Why does viscosity not control blood flow?
It remains constant under physiological conditions and therefore does not control blood flow.
What is the most important factor in determining resistance?
The radius of the vessel.
How can the radius of the blood vessels be regulated?
Using smooth muscle.
