The heart is a pump that circulates blood all around the body. It is approximately the size of a human fist and is located just to the left of the centre of a human’s chest. On average, the heart beats between 60-70 times a minute at rest.
The heart is made of a special type of muscle called the cardiac muscle. This type of muscle has certain characteristics that make it perfectly suited for its job. Firstly cardiac muscle consists of branching muscle fibres connected to each other in a network, this allows for contractions to begin at one point in the heart and spread outwards in all directions. Secondly cardiac muscle naturally contracts and relaxes rhythmically in “beats”. Thirdly cardiac muscle does not get tired or fatigued even though it is continuously working throughout our lifetime.
The heart is in fact a double pump. The right side of the heart is considered as one pump and the left side of the heart is the second pump. A thick wall called the septum separates the two sides. The right side of the heart carries deoxygenated blood to the lungs to be oxygenated. The left side of the heart pumps oxygenated blood to the rest of the body.
Animation: The Heart
Look at the animation below to see how the heart works to pump blood around the body.
Below is a fully labelled image of the cross-section of the human heart