Final answer:
Blood first enters arteries, such as the aorta, when it leaves the heart. The flow sequence is aorta, arteries, capillaries, venules, and then veins. Arteries carry blood away from the heart; veins return it after gas exchange in the lungs.
Step-by-step explanation:
When blood leaves the heart, it first enters a type of blood vessel known as an artery. The arteries are responsible for transporting blood away from the heart. The main artery of the systemic circulation is the aorta, which branches out into other major arteries that distribute the blood to various parts of the body.
The order in which blood flows from the heart out to the body and back again is:
- Aorta,
- Arteries,
- Capillaries,
- Venules,
- Veins
.
Arteries and veins both have valves that prevent the backflow of blood, ensuring a one-way circulation system. In the lungs, blood becomes oxygenated through gas exchange before being carried back to the heart by veins.