NREMT Paramedic Practice

What is the mean arterial pressure (MAP) primarily a function of?

1. Venous return and heart rate

2. Total cardiac output and total peripheral resistance

3. Blood volume and blood viscosity

4. Heart rate and stroke volume

The correct answer is: Total cardiac output and total peripheral resistance

Mean arterial pressure (MAP) is primarily determined by total cardiac output and total peripheral resistance. Cardiac output refers to the volume of blood the heart pumps per minute, which is calculated as the product of stroke volume (the amount of blood ejected with each heartbeat) and heart rate (the number of heartbeats per minute). Total peripheral resistance represents the resistance that the arteries and arterioles provide to blood flow. When resistance is increased (due to factors such as vasoconstriction), the MAP will also increase if cardiac output remains stable. Conversely, a decrease in cardiac output will lead to a drop in MAP unless there is a compensatory increase in resistance. Therefore, MAP is a critical indicator of perfusion pressure and is influenced by both the heart's output and the vascular resistance against which the heart must pump. In summary, the interaction between total cardiac output and total peripheral resistance is key to understanding how MAP is regulated and maintained in the cardiovascular system. This relationship highlights the significance of both components in determining blood pressure and ensuring adequate tissue perfusion.