15. Haemodynamics

Question 1

What is the equation for blood flow?

Answer 1

Q= delta P/R

Question 2

Equation for resistance?

Answer 2

8nl/πr^4

Question 3

What is Poiseulle’s law?

Answer 3

Flow depends directly on pressure and radius of arterioles

Depends inversely on viscosity and length

Question 4

Explain laminar flow

Answer 4

Viscous blood flows in cylindrical layers through the blood vessel due to more resistance against walls
Increased effect of friction in smaller vessels because all blood is near the walls

Question 5

What is turbulent flow caused by?

Answer 5

Narrow areas with high velocity flow

Question 6

What four factors determine viscosity?

Answer 6

Haematocrit
Temperature
Velocity
Size of vessels

Question 7

What is transmural pressure?

Answer 7

The amount of pressure needed to collapse a blood vessel
Transmural pressure is the inside pressure- outside pressure
If outside pressure is greater then the vessel collapses
=wall tension/radius

Question 8

What is the Law of La Place

Answer 8

T=Pr
Wall tension= transmural pressure x radius
T= thickness of the vessel wall needed to hold blood
smaller radii need smaller walls

Question 9

What is the equation for compliance?

Answer 9

C=delta V/delta P