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The purpose of the cardiovascular system (sometimes called the circulatory system) is to move blood throughout the body. Blood provides our tissues with oxygen and other necessary materials. It also aids in the removal of carbon dioxide.
The cardiovascular system is composed of:
The five different types of blood vessels work together to transport the blood that is pumped by the heart. The diagram below shows how they are connected.
When blood first leaves the heart, it travels through the arteries, which are large in diameter. An artery has a large diameter and is made up of several layers.
The layers include:
IN CONTEXT
Have you ever taken your pulse following a workout? What is this that you are feeling?
When you measure your pulse, what you are actually measuring is the pressure surge in arteries when the ventricles within your heart contract. You can feel your pulse at different parts of your body, either on your wrist or by your carotid artery near your neck.
Arteries then branch off into arterioles. Arterioles are similar to arteries in that they also carry blood away from the heart, but arterioles are smaller in diameter. They have a couple of different layers:
Arterioles will eventually branch into capillaries, which are even smaller in diameter.
Capillaries are the smallest blood vessel in our body and are where substances are allowed to diffuse from the blood into tissues. This can happen because they are made of a single, very thin layer of endothelium. Blood moves very slowly in capillaries, and, because of the amount of capillaries in our body, they offer less resistance to blood flow than arterioles.
From there, capillaries will start to branch back into venules. Venules are larger in diameter than capillaries but are still small and still allow for some substances to diffuse. They start the transport of blood back to the heart.
From here, blood moves into veins, which have a larger diameter than venules. The purpose of veins is to transfer blood back to the heart. They have low resistance, but a unique thing about veins compared to some of our other vessels is that they have valves. Because blood traveling in veins is going against gravity, veins have valves that prevent backflow, creating a one-way system of flow back to the heart.
The contraction of the smooth muscle means stiffer walls of the vein. This creates a rise in pressure, which, in turn, equals more blood flow to the heart.
EXAMPLE
An example of how this works and its importance can be seen when you exercise. Those smooth muscles will contract, and then that will cause the walls of the blood vessels to stiffen. Your blood pressure will rise, and then more blood will be delivered to your heart more quickly.Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND