Tue28September1204PM 9

Which of the following does not affect resistance to flow in a blood vessel?

(Please select 1 option)

Length of the vessel

Thickness of the vessel wall Correct

Haematocrit

Radius of the vessel

Pressure gradient

Explanation

This question refers to Poiseuille's formula. Flow (Q = Ppr4/8L)

P is the pressure gradient along the vessel

Q is the flow rate

r is the radius of the vessel

is the coefficient of viscosity (haematocrit) of the blood

L is the length of the blood vessel.

Resistance is pressure difference/flow (P/Q) (analogous to Ohm's law)

Rearranging Poisulle's equation P/Q =8L/pr4

Thickness of the vessel wall does not affect blood flow, but the stiffness of the vessel wall does affect blood flow.

Answer Statistics

1

3%

2

92%

3

4%

4

1%

5

2%

Times answered: 264