Blood flows in our bodies through an intricate system of blood vessels known as the circulatory system. The movement is facilitated by the pumping of the heart and with every heart beat blood is pushed through the different blood vessels that go through every part of the body. There are three distinct types of blood vessels that perform different roles:
Arteries- These are blood vessels that carry blood rich in oxygen away from the heart. They comprise of arteries such as the pulmonary artery and the aorta. They also play a role in maintaining the consistency of the blood pressure. The arteries branch into smaller arterioles as they move further away from the heart.
Veins- These are blood vessels that carry blood poor in oxygen back to the heart. They have narrower walls compared to the arteries. They are flexible and expand to accommodate the different amounts of blood that go through them.
Capillaries- These are blood vessels that connect the arteries and the veins. They feature very thin walls to allow for oxygen and nutrients to pass through and reach the body tissues. They are also responsible for the movement of wastes from the tissues back to the blood and released through organs such as the lungs.
Blood deficient in oxygen arriving from the veins is pumped from the heart to the lungs while, blood rich in oxygen moves from the lungs to the heart through the pulmonary veins and then to the rest of the body.