Control of blood flow Flashcards
What is G?
G= conductance which is the reciprical of TPR
Equation for cardiac output in relation to conductance and pressure gradient
CO=Pressure gradient x Conductance
What does TPR control?
TPR controls blood flow and blood pressure
What does an increase in resistance mean?
Increase in resistance means you need to increase pressure to keep the same flow
What controls TPR?
o Poiseulle’s Law
o Myogenic response
o Blood viscosity
Blood flow equation
Blood flow(CO)=Pressure gradient/TPR
What is hypertension?
Over constriction of arterioles
What does hypertension lead to and cause?
Higher arterial BP but less capillary flow causing under perfusion
What causes blood flow?
Pressure drop between arteries and arterioles
What does a decrease in TPR lead to?
Decrease in TPR, decreased blood pressure upstream but greater flow due to vasodilation
What does an increase in TPR lead to?
Increase in TPR, increased blood pressure upstream but less flow due to vasoconstriction
Sedentary VS Exercise of Superior mesenteric
Dilated at sedentary-Increased flow to intestine
Constricted during exercise leading to a decreased flow to intestines
Sedentary vs Exercise of Common iliac
Constricted at sedentary-Decreased blood flow at rest
Dilated during exercise-Increased flow to legs
What does Poiseuille’s law describe?
Describes parameters that govern TPR
What does Poiseuille’s law illustrate?
It illustrates why the radius of a vessel is such an important determinant in changing blood flow
What is the r^4 effect?
Double radius size from 1mm to 2mm can cause a change to r^4 by 16 times
What does the r^4 effect show?
A small change in size of radius can have a massive impact
What do vasoconstrictors or dilators produce?
Produce small changes in vessel radius by affecting smooth muscle and have large effects on blood flow
What are the main vessels involved in TPR
Arterioles Are The Main Vessels Involved in TPR
What have the largest drop?
Arterioles have the largest drop