A 0.5 litre blood loss in 30 minutes will lead to
**Question:** A 0.5 litre blood loss in 30 minutes will lead to
A. Decreased blood volume
B. Increased blood volume
C. Increased heart rate
D. Increased blood pressure
**Core Concept:** Blood volume and blood pressure are closely related parameters in human physiology, particularly in maintaining cardiovascular stability. A decrease in blood volume can lead to compensatory mechanisms to maintain blood pressure.
**Why the Correct Answer is Right:** When there is a loss of 0.5 litre blood over 30 minutes, there is a decrease in blood volume. This triggers the body's compensatory mechanisms, such as increased heart rate (tachycardia) and vasoconstriction, to increase the cardiac output and blood pressure.
**Why Each Wrong Option is Incorrect:**
A. **Increased blood volume** is incorrect because the loss of blood volume would lead to compensatory mechanisms to maintain blood pressure.
B. **Increased blood pressure** is incorrect as the primary focus should be on maintaining blood volume rather than increasing blood pressure directly.
C. **Increased heart rate** is correct as an increase in heart rate (tachycardia) is one of the compensatory mechanisms to increase cardiac output and maintain blood pressure during a decrease in blood volume.
D. **Decreased heart rate** is incorrect since a decrease in heart rate (bradycardia) would not be a compensatory mechanism during blood volume loss.
**Clinical Pearl:** When dealing with blood volume loss, maintaining blood volume is crucial as it directly impacts cardiovascular stability. The body compensates by increasing heart rate (tachycardia) and vasoconstriction. However, the primary focus should be on maintaining blood volume, not just blood pressure.
**Correct Answer:** C. Increased heart rate (tachycardia) is the correct answer as it is a compensatory mechanism to increase cardiac output and maintain blood pressure during a decrease in blood volume. This is essential for maintaining cardiovascular stability and ensuring adequate oxygen and nutrient delivery to vital organs.