Question

For each of the physiological changes A–E, select the most appropriate option from the possible precipitating causes listed below. 

1. Fainting. 

2. Severe haemorrhage. 

3. Severe exercise. 

4. Late pregnancy. 

5. Hypothermia. 

6. Lying down. 

A. A fall in the haematocrit. 

B. A decrease in heart rate. 

C. A decrease in oxygen consumption. 

D. A reduction in venous capacity. 

E. An increased right atrial pressure.

Answer 1

A. Option 4 Late pregnancy. The relative increase in plasma volume in late pregnancy results in a low haematocrit. 

B. Option 1 Fainting. The vagal element of the vaso-vagal faint can cause severe bradycardia. 

C. Option 5 Hypothermia. The decrease in the metabolic rate in hypothermia reduces oxygen consumption. 

D. Option 2 Severe haemorrhage. The intense reflex venoconstriction in severe haemorrhage may make it difficult to insert catheters for introducing intravenous fluids. 

E. Option 6 Lying down. Due to the increase in venous return to the heart.