Usually there is only one capillary bed between an artery and vein; an exception to this is the:

Hepatic portal system

Explanation:

The hepatic portal system is the system of veins which carries the deoxygenated blood from the stomach, spleen and intestine to the liver.

Since the hepatic cells are present in the liver which detoxifies the blood therefore the system of veins is known as the hepatic portal system.

The hepatic system begins in the capillaries of the digestive system and brings it to the liver through the hepatic portal vein.

Thus, Hepatic portal system is the correct answer.

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.