A 56-year old woman has a mean systemic blood pressure of 100 mm Hg and a resting cardiac output of 4 L/min. What is the total peripheral resistance of this woman?
**Core Concept**
The underlying principle being tested is the relationship between mean arterial pressure, cardiac output, and total peripheral resistance, which is described by the equation: Mean Arterial Pressure (MAP) = Cardiac Output (CO) x Total Peripheral Resistance (TPR). This equation is fundamental to understanding cardiovascular physiology.
**Why the Correct Answer is Right**
To find the total peripheral resistance, we use the formula TPR = MAP / CO. Given that the mean systemic blood pressure (MAP) is 100 mm Hg and the cardiac output (CO) is 4 L/min, we can calculate the TPR as 100 mm Hg / 4 L/min = 25 mm Hg/L/min. This calculation directly leads to the identification of the correct answer based on the provided options.
**Why Each Wrong Option is Incorrect**
**Option A:** This option would be incorrect if it does not match the calculated value of 25 mm Hg/L/min, as this is the value derived from the given MAP and CO.
**Option B:** Similarly, if this option does not align with the calculated TPR, it is incorrect.
**Option C:** This option is incorrect if it does not represent the calculated TPR of 25 mm Hg/L/min.
**Option D:** This option is wrong if it does not match the calculated value, which is necessary for the correct answer.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that total peripheral resistance is a critical determinant of blood pressure and is influenced by factors such as vessel diameter and compliance. Understanding this relationship is essential for managing hypertension and other cardiovascular conditions.
**Correct Answer:** 25 mm Hg/L/min