For each of the physiological characteristics A–E, select the most appropriate option from the special circulations listed below

A. Option 5 Skin blood flow. Skin blood flow increases during sweating due to an active sympathetic cholinergic mechanism.

B. Option 1 Coronary blood flow. Coronary blood flow is decreased during systole because of compression of the vessels by the contracting ventricular myocardium.

C. Option 3 Splanchnic blood flow. Splanchnic blood flow passes through two capillary beds in one circuit of the circulation, firstly through the capillaries in the alimentary tract and then through a portal capillary bed in the liver.

D. Option 4 Cerebral blood flow. Cerebral blood flow is little affected by cardiovascular reflexes. However it is very sensitive to changes in the PCO2 of the perfusing blood.

E. Option 2 Skeletal muscle blood flow. Vasodilatation in skeletal muscle during fainting causes a large fall in peripheral resistance and is one of the factors leading to the fall in arterial pressure that results in the faint.