The circulation collects nutrient-rich venous blood draining from the digestive viscera. a) enterohepatic b) splanchnic c) hepatic d) portal e) pulmonary.

The answer is C: Hepatic Portal

Explanation:

The hepatic portal circulation is a venous system responsible for draining blood from the digestive tract (stomach, intestine) and spleen to the capillaries in the liver. The main vessel of the hepatic portal system is the hepatic portal vein which is formed by the confluence of the gastric vein, the pancreaticomesenteric and lienomesenteric veins.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

layer 3 is younger than layer 6.