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The Circulatory System

The circulatory system is an essential part of the human body but what is it?

The circulatory system refers to the movement of blood through the heart and around the body.

Your heart plays a key role in the circulatory system. It is a muscular organ that acts like a pump. It is about the size of your fist and is located to the left of your chest. Your heart is divided into the right and left side. This keeps the oxygenated and deoxygenated blood apart. Within the heart, there are special valves, which prevent the blood from flowing in the wrong direction. They only open one way and do so once per heartbeat.
Your heart and blood vessels work together to carry blood around the body, ensuring that every living cell is provided with water, nutrients and oxygen, but how does it work?

Before each beat of the heart, the heart fills with blood. Since the heart is a muscle, it can contract – or squeeze together – and force the blood away from the left-hand side of the heart. The blood travels through arteries. Arteries are different from other blood vessels. This is because they have thicker walls in order to withstand the pressure created by the blood as it leaves the heart. The oxygen-rich blood leaving the heart travels via the aorta. This is the main artery leaving the heart. From here, it travels to the rest of the body.

As the blood reaches the living cells around the human body, the oxygen is removed by the body’s cells and replaced with carbon dioxide. This is the waste product created when the cells use the oxygen. The blood can reach every living cell by travelling through a network of much smaller blood vessels known as capillaries.

Now it is time for the deoxygenated blood to return to the heart to collect more oxygen and deposit the waste material it has collected. It does this by means of blood vessels called veins.

Next, the returning, deoxygenated blood enters the right side of the heart through the vena cava. Once the blood is in the right ventricle, it is pumped into the lungs, where the carbon dioxide is removed. This leaves the body when we exhale. As we inhale, oxygen enters the lungs and is transferred into the blood in a process called ‘diffusion’. This oxygenated blood is then transported to the heart and the whole process can start again!

Even though there a variety of stages within the process, all of this takes an average of fifty-five to sixty seconds to complete. Amazingly, it is estimated that your heart beats around 100,000 times a day! The constant exchange of oxygenated and deoxygenated blood is what keeps us alive.