Question

The flow rate (F) of blood through a blood vessel describes the volume of blood that passes through the vessel per a unit of time. Flow rate is affected by physical variables like the resistance of the blood vessel (R) and the pressure gradient within the blood vessel (∆P). Which one of the following statements correctly summarizes the relationships between these variables?

*Hint: F = ∆P/R

Select one:

a) Flow rate is equivalent to the pressure gradient multiplied by the resistance.

b) Flow rate is equivalent to the pressure gradient minus the resistance.

c) Flow rate is directly proportional to the pressure gradient and inversely proportional to the resistance.

d) Flow rate is directly proportional to the resistance and indirectly proportional to the pressure gradient.

Answer 1

c) Flow rate is directly proportional to the pressure gradient and inversely proportional to the resistance.

Explanation: Flow rate is directly proportional to the pressure gradient, when the pressure gradient is higher the rate of flow will be higher and when the pressure gradient is lower the rate of flow will also be lower. This is because larger pressure difference across the vessel helps to push the blood more powerfully in forward direction so the flow rate becomes higher.

Flow rate is inversely proportional to the resistance. When the Resistance is high, then blood flow decreases and when the resistance is low, the blood flow increases.