• LC&VA

The heart: what it does and how!

The human heart is of course a vital organ – you simply cannot live without it! It functions like a pump sending blood around your body, keeping you alive. The heart is made out of muscle and is roughly the size of a fist. It is located in the middle of your chest tilted just a little to the left.


Every day your heart pump about 100,000 times moving approximately 5 litres of blood around the body, delivering blood to other organs. This is achieved by the blood travelling through a network of vessels of varying size called the circulatory system. It is important that the blood reaches these organs because it delivers oxygen and vital nutrients whilst removing carbon dioxide and other waste products. Without you heart and your circulatory system your organs and therefore your body just would not function. That’s why it is important to keep your heart healthy and regularly checked.



So, what does the heart look like?

There are three layers of tissue which make up the heart muscle:

  • Pericardium – a thin outer layer which is protective

  • Myocardium – this is the thick muscular layer which is responsible for pumping the blood

  • Endocardium – the thin inner lining.

The heart is made up of four chambers – two on the left and two on the right-hand side. The left and right sides of the heart are separated by a muscular wall which is known as the septum. The two upper chambers are called atria and are smaller whilst the lower two are called ventricles.


The heart has a natural pacemaker called the sinus node which sends signals through the heart muscle telling it to contract. There are some clever valves in the heart which act like one-way gates – letting the blood through in the right direction but not letting it flow back the wrong way. There are two sets of valves on each side of the heart:

  • Tricuspid valve and pulmonary valve on the right side.

  • Mitral valve and aortic valve on the left side.

How does this all work together to pump blood?

  1. The left and right side of the heart might be separate but they do work together.

  2. The right side of the heart receives blood without oxygen in (de-oxygenated) – this has come from the rest of the body.

  3. The right side of the heart contracts and pushes this blood to the lungs where is collects a fresh supply of oxygen.

  4. The blood comes back to the heart into the left side, which contracts and pushes the blood out of the heart to feed the rest of the body.

  5. When the blood leaves the heart, it travels through the aorta (big artery leaving the heart) and into smaller arteries. These then branch out into smaller and smaller vessels called capillaries which reach the whole of the rest of the body.

  6. Once the blood has been to the organs and cells and has delivered the oxygen and nutrients it returns via the veins to the right side of the heart.



But how does the heart keep going?

Like all the other organs in your body the heart needs blood carrying oxygen and nutrients in order to function. These are delivered by the coronary arteries which branch off the aorta (big artery leaving the heart) and cover the outside of the heart.


The heart and circulatory are so vital therefore if you are worried about anything or think there might be an issue, however small it is always a good idea to have it checked, even if just to put your mind at ease.


This article is intended to inform and give insight but not treat, diagnose or replace the advice of a doctor. Always seek medical advice with any questions regarding a medical condition.

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Photo credit Giulio Mazzarini

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