Question

Mean arterial pressure is ________ (indirectly/directly) proportional to ________ and ________ (indirectly/directly) proportional to ________.

Answer 1

Answer: Mean Arterial Pressure is directly proportional to Cardiac Output and Systemic Vascular Resistance and also directly proportional to Central Venous Pressure.

Explanation: Based on the relationship of flow, pressure and resistance, the mean arterial pressure is determined by the cardiac output (CO), systemic vascular resistance (SVR), and central venous pressure (CVP). This relationship is given by:

MAP = (CO x SVR) + CVP

Which is alternatively expressed as:

MAP = CO x SVR (this is because at any point in time in blood circulation, the central venous pressure is always near to zero mmHg.

Due to this direct relationship, any factor affecting the cardiac output and the Systemic Vascular Resistance would cause a corresponding change in the Mean Arterial Pressure.

It is also worthy to note that If Cardiac Output and Systemic Vascular Resistance change reciprocally (inversely) and proportionately, then Mean Arterial Pressure will not change. The plotted graph is one of positive slope.

The whole relationship occurs when blood is pumped out of the left ventricle into the aorta and distributing arteries, creating pressure.