The normal heart

Last updated December 2021

Understanding the normal flow of blood through the heart can be daunting so here we have described it in two ways.

The heart is a clever pump. Its job is to collect and send blood to different parts of the body. Blood contains all the things we need to make energy: oxygen, nutrients (food) and water, which it takes to every part of the body so that every part of the body has the energy it needs to work, grow and repair.

The body’s circulation has red blood that is filled with oxygen and blue blood that is empty of oxygen.

The heart has two sides. The right side’s job is to collect blue blood from the head, neck and body into the top right chamber (the right atrium). It then passes into the bottom chamber (the right ventricle) which pumps the blood to the lungs.

The lungs do their job and pass oxygen into the blood; this turns the blood red. This oxygen-filled blood then needs to be pumped around the body by the heart. The red blood is collected in the top left chamber (the left atrium) and then passes to the lower chamber (the left ventricle) that pumps the blood out of the heart and around the body.

The body uses all the oxygen in the blood, turning the blood blue, and then sends it back to the right side of the heart to start the journey all over again. The following paragraphs explain the heart again but use more of the terms you may hear from your medical team and the picture looks more like a real heart.

This is how the journey begins: blood returns from the body, via the superior vena cava and the inferior vena cava, to the right side of the heart into a collecting chamber (right atrium). This blood has a bluish tinge (blue blood) because the body has taken (extracted) all the oxygen from it (deoxygenated blood).

The blood passes through a valve (tricuspid valve) into a pumping chamber (right ventricle), which then pumps the blood to the lungs via the lung arteries (pulmonary arteries).

As the blood passes through the lungs it picks up oxygen: this turns the blood a red colour (oxygenated blood). This blood flows to the left collecting chamber (left atrium) and then passes through a valve (mitral valve) to the left pumping chamber (left ventricle).

The left ventricle then pumps blood to the body through a valve (aortic valve) via the main body artery (aorta).

The body uses the oxygen from the blood to help make energy. As the oxygen is used up, the blood takes on a blue colour and needs to return to the lungs to collect more oxygen. The journey then starts again.

Below you will find an animation about the normal heart – A visual guide to help you understand the information on this page.