There is a reason that the term “heart” is used to describe something that is central and essential – the kitchen being the heart of a home, for example: the organ is vital, in the true sense of the word, to human survival.

The heart is a muscle like no other, beating around 100,000 times every single day. It is a strong organ, made mostly of indefatigable cardiac muscle which contracts rhythmically of its own accord. This is the middle of three layers of tissues, known as the myocardium. The outer layer is called the pericardium, and is a tough yet thin protective membrane, while the thin inner lining is known as the endocardium.

Blood, now much darker in colour because the oxygen has been taken up by all the parts of the body and replaced with carbon dioxide, re-enters the heart via the vena cava into the right atrium, and passes through the tricuspid valve into the right ventricle.

From here, the deoxygenated blood passes through the pulmonary valve into the pulmonary artery where it goes to the lungs in order for carbon dioxide to be exchanged for oxygen. And so the cycle continues.