Final answer:
The main difference between arterial and venous blood is that arterial blood is rich in oxygen and transports it from the lungs to the body, while venous blood is rich in carbon dioxide as it returns from the body to the lungs.
Step-by-step explanation:
Main Difference Between Arterial and Venous Blood
The main difference between arterial and venous blood is their content of oxygen and carbon dioxide. Arterial blood carries oxygen from the lungs to the body's tissues and organs, while venous blood carries carbon dioxide, a waste product, from the body's tissues back to the lungs for exhalation. When considering the pulmonary and systemic circuits, the pulmonary arteries and systemic veins carry oxygen-poor blood, but in the pulmonary circuit, the veins carry oxygen-rich blood back to the heart, opposite to the systemic circuit. In the systemic circuit, arterial blood has a high partial pressure of oxygen as it delivers oxygen to body tissues. In contrast, venous blood reaching the alveoli in the lungs has a lower partial pressure of oxygen, having given up its oxygen to tissues and having collected carbon dioxide.
Both arteries and veins consist of three layers and participate in a network that includes capillaries. Capillary beds exchange nutrients, oxygen, and waste at the cellular level and are connected to arterioles and venules. The aorta is the main artery that distributes oxygen-rich blood from the heart to the major arteries, which then deliver blood to various organs. Veins have thinner walls and larger lumens than arteries due to the lower pressure of venous blood, and they contain valves to prevent backflow. Significant veins and arteries, like the pulmonary arteries and the aorta, have specific roles in blood circulation.