Question

For each of the features of the capillary circulation A–E, select the most appropriate option from the possible locations and precipitating causes listed below. 

1. In the brain. 

2. In Vitamin C deficiency. 

3. In exercising muscle. 

4. After haemorrhage. 

5. In the spleen. 

A. High permeability. 

B. Low permeability. 

C. High fragility. 

D. Net outflow of fluid. 

E. Net inflow of fluid.

Answer 1

A. Option 5 In the spleen. Splenic capillaries, because of the large slits between adjacent endothelial cells, are freely permeable to most solutes. 

B. Option 1 In the brain. Because of the ‘blood–brain barrier’, cerebral capillaries are much less permeable than capillaries elsewhere in the body so that tissue fluid in the brain differs in composition from that of plasma. 

C. Option 2 In Vitamin C deficiency. Capillary (petechial) haemorrhages are a feature of scurvy caused by Vitamin C deficiency. 

D. Option 3 In exercising muscle. Because the arteriolar vasodilation raises capillary pressure. 

E. Option 4 After haemorrhage. Because arteriolar constriction decreased capillary pressure.