Circulatory System

The circulatory system (cardiovascular system) is the organ system that circulates blood throughout the body via the heart and blood vessels. Its primary purpose is to deliver oxygen and nutrients to tissues and to carry away carbon dioxide and other waste products for elimination.

• Major components: the heart (muscular pump), arteries (vessels carrying blood away from the heart), capillaries (tiny vessels where exchange of gases/nutrients occurs), and veins (vessels returning blood to the heart).
• Humans have a <u>closed circulatory system</u>, meaning blood stays within vessels. There are two circuits: the pulmonary circulation (heart to lungs and back, for gas exchange) and systemic circulation (heart to body and back).
• Arteries generally carry oxygenated blood and veins carry deoxygenated blood, with a notable exception: the pulmonary arteries carry oxygen-poor blood from the heart to the lungs, and pulmonary veins carry oxygen-rich blood back to the heart.

• Look for clues about oxygen delivery or waste removal. For example: "Which system transports oxygen to cells and removes carbon dioxide?" - the circulatory system.
• Common trap: assuming all arteries carry oxygenated blood. A classic question might ask which artery carries deoxygenated blood - the correct answer is the pulmonary artery (since it goes to the lungs to pick up oxygen).