Complete the following statements by filling in the blanks from the choices given in the brackets.

(a) The blood vessel that begins and ends in capillaries is the ………………… (hepatic artery, hepatic portal vein, hepatic vein).

(b) A blood vessel which has small lumen and thick wall is …………. (capillary, lymphatic duct, artery, venule)

(c) The valve which prevents back flow of blood in the veins and lymph vessels…… (mitral valve, tricuspid valve, semilunar valve).

(a) The blood vessel that begins and ends in capillaries is the hepatic portal vein.

Explanation: A portal vein is one which begins and ends in capillaries. The hepatic portal vein is one which begins as a capillary from stomach and intestine and ends as a capillary in liver.

(b) A blood vessel which has small lumen and the thick wall is an artery.

Explanation: An artery is identified by the presence of its narrow lumen and thick muscular walls. As they are deep seated in the body surrounded by tissues on all the sides, with the help of the thick muscular walls they don't develop cracks in their walls.

(c) The valve which prevents back flow of blood in the veins and lymph vessels semilunar valve

Explanation: Semilunar valves are present at the junction between right auricle and pulmonary artery in the heart. Here the blood is carried away from the heart against gravity. So to prevent backflow of blood veins are provided by valves.