(a) What blood vessels contribute to the formation of the hepatic portal circulation? (b) Why is a portal circulation a “strange” circulation? Physiologists often consider capillaries and...

(a) What blood vessels contribute to the formation of the hepatic portal circulation?

(b) Why is a portal circulation a “strange” circulation?

Physiologists often consider capillaries and postcapillary venules together.

(a) What functions do these vessels share?

(b) Structurally, how do they differ?