Write an essay explaining why,for example,amino acids leave the blood through the arterial end,and organic wastes enter it via the venous end.

A capillary bed (made of numerous capillaries) has an arterial and venous end. Exchanges of nutrients, gases, and wastes between blood and interstitial space in opposite directions occur specifically at these so-called ends.

Write an essay explaining why,for example,amino acids leave the blood through the arterial end,and organic wastes enter it via the venous end.
(exceed 800 words.)