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

A. Option 3 Pulmonary circulation. Pressure in the pulmonary circuit is much lower than that in the systemic circuit since it offers much less resistance to flow.

B. Option 1 Hypothalamic circulation. The capillary bed in the hypothalamus is connected by blood vessels to a second capillary bed in the anterior pituitary gland. This allows hormones secreted in the hypothalamus to be carried to the pituitary where they lead to the release of certain pituitary gland hormones.

C. Option 2 Coronary circulation. Coronary arteries, though they are connected by anastomotic vessels act as functional end arteries so that when one is blocked the ventricular muscle served by that artery dies.

D. Option 4 Fetal circulation. During fetal life, blood returning from the placenta to the right atrium bypasses the pulmonary circuit by (i) passing through the foramen ovale; and (ii) being diverted from the proximal part of the pulmonary artery via the ductus arteriosus to the aorta.

E. Option 5 Cerebral circulation. The circle of Willis is a vascular arrangement at the base of the brain into which all the main arteries to the brain connect so that if one artery should block, the brain can still be supplied by the other arteries in this anastomotic arrangement.