What are the two types of blood circulation in humans?

1. PULMONARY CIRCULATION — between the heart and the LUNGS. Deoxygenated blood goes from the right ventricle to the lungs by the pulmonary artery, and oxygenated blood returns to the left atrium by the pulmonary veins.
2. SYSTEMIC CIRCULATION — between the heart and the REST OF THE BODY. Oxygenated blood goes from the left ventricle to the body tissues through the aorta, and deoxygenated blood returns to the right atrium through the venae cavae.

One mark each. Name the circulation AND say what it connects; the names alone are worth less.

Because the blood passes through the heart TWICE in one complete circuit of the body, the human system is called DOUBLE CIRCULATION — a term worth adding.

THE ADVANTAGE of keeping the two circuits separate: oxygenated and deoxygenated blood never mix, so the blood sent to the tissues is fully oxygenated. It also allows the two circuits to run at different pressures — the systemic circuit needs high pressure to reach the whole body, while the pulmonary circuit must stay at low pressure to avoid damaging the delicate lungs. That is why the left ventricle wall is much thicker than the right.