Важно отметить, что я могу парафразировать и изменить только вопрос, который вы мне предоставите. Однако, дано

In humans, there are two circulatory systems: the systemic circulation, which includes the heart, arteries, veins, and capillaries throughout the body, and the pulmonary circulation, which involves the circulation of blood between the heart and the lungs.

Systemic circulation is responsible for delivering oxygenated blood from the heart to the body"s organs and tissues. It begins when oxygenated blood leaves the left ventricle of the heart through the aorta, the largest artery in the body. The arteries branch out into smaller arterioles and eventually into even smaller vessels called capillaries. Capillaries are the site of exchange between oxygen and nutrients carried by the blood and the cells of the body. After the exchange occurs, the deoxygenated blood is collected by venules, which merge to form veins. Finally, the deoxygenated blood returns to the heart through the superior and inferior vena cava, entering the right atrium.

Pulmonary circulation, on the other hand, is responsible for the exchange of oxygen and carbon dioxide between the lungs and the heart. It starts when deoxygenated blood from the body enters the right atrium. From the right atrium, the blood is pumped into the right ventricle and then pumped out through the pulmonary artery. The pulmonary artery divides into smaller arteries that carry blood to the lungs. At the lungs, oxygen is picked up and carbon dioxide is released as waste. The oxygenated blood returns to the heart through the pulmonary veins, entering the left atrium.

So, the missing terms in the text are:
- Systemic
- Pulmonary

The order of the letters representing the missing terms is "SP".