The blood flowing away from the stomach and intestine is put into the circulation via the liver and not directly because the liver monitors all the substances that have to be circulated in the body. The excess nutrients such as glucose, fats are stored in the liver. The excess amino acids are broken down by deamination and the toxic substances are detoxified. The hepatic portal vein arises from the stomach and small intestine and carries the blood to the liver for the absorption of nutrients and detoxification of toxic substances, therefore the portal vein is the one that arises from the capillaries and also ends in the capillaries .

The heart is a muscular organ located in the thoracic cavity in between the two lungs. The cardiac muscles of the heart contract and expand alternatively to pump the blood into the blood vessels. When the heart muscles contract, the blood is pushed into the blood vessels. The muscle of the heart expands when the blood is forced into the chambers of the heart. This contraction and expansion of heart muscles is a cyclic process. The expansion of the artery each time the blood forced into it is called the pulse . The pulse rate can be calculated by using a stethoscope. The pulse rate of an adult person while resting is 70-72 per minute.