PATHOLOGY

Detailed explanation-1: -The capillary beds around the GI tract are open during a meal and closed between meals, during exercise, and during sleep (which is also between meals).

Detailed explanation-2: -hepatic portal vein: A vessel located in the abdominal cavity that is formed by the union of the superior mesenteric and splenic veins that channel blood from the gastrointestinal tract and spleen to the capillary beds in the liver.

Detailed explanation-3: -The capillaries are responsible for facilitating the transport and exchange of gases, fluids, and nutrients in the body. While the arteries and arterioles act to transport these products to the capillaries, it is at the level of capillaries where the exchange takes place.