About your body
The Heart
The heart is the organ in your body that pumps blood. It is shaped a little like an upside-down pear and is about the size of a clenched fist. In adults it weighs between 300g and 450g.
The heart’s job is to pump blood around the body. Blood, stripped of oxygen and bluish in colour, enters the right-hand side of your heart. From here it is pumped out to your lungs where it picks up oxygen and it becomes more reddish in colour. Some of the carbon dioxide in your blood is dumped back into your lungs at the same time. The reddish coloured, or oxygenated blood, then returns to the left-hand side of your heart to be pumped out again through your body where it delivers oxygen and nutrients.
Our hearts have four chambers, two upper chambers called the left and right atrium. The two lower chambers are called the left and right ventricles. The heart also has valves that prevent the blood from flowing in the wrong direction.
Each minute, the heart pumps about 5-7 litres of blood around your body and through your lungs. Each day your heart can beat about 100,000 times!
A normal adult heart will beat between 60-100 times a minute and this can increase dramatically when you exercise or get really stressed or scared.