How the heart works


The heart is responsible for circulating blood throughout the body. It is about the size of your clenched fist and sits in centre of the chest cavity between your two lungs. Its walls are made up of muscle that can squeeze or pump blood out every time the heart “beats” or contracts. Fresh, oxygen-rich air is brought into the lungs every time you take a breath. The lungs are responsible for delivering oxygen to the blood, and the heart circulates the blood through the lungs and out to the different parts of the body.


The heart is in effect two pumps, working side by side, the left and the right sides. Each side is subdivided into an upper and a lower chamber. The upper chamber is known as the atrium (pronounced AY-tree-yum) while the lower chamber is referred to as the ventricle (pronounced VEN-trickle). The right atrium (RA) sits on top of the right ventricle (RV) on the right side of the heart while the left atrium (LA) sits atop the left ventricle (LV) on the left side.


The right side of the heart (RA and RV) is responsible for pumping blood to the lungs, where the blood cells pick up fresh oxygen. This oxygenated blood is then returned to the left side of the heart (LA and LV). From here the oxygenated blood is pumped out to the rest of the body through the arteries, supplying the fuel that the body cells need to function. The cells of the body remove oxygen from the blood, and the oxygen-poor blood is returned through the veins to the RA, where the journey began. This round trip is known as the circulation of blood.





What is a heart attack?

Heart attacks are the most common result of coronary heart disease. Someone has a heart attack when their coronary arteries become blocked. This stops blood flowing freely to the heart, so it can’t get the oxygen it needs. Starved of oxygen, the heart can’t pump properly, and in severe cases it may effectively stop beating altogether, which can kill you. Damage to the heart muscle because of a heart attack can lead to heart failure – when your heart can no longer pump blood around your body normally. This leads to symptoms such as swelling of the ankles and shortness of breath, which affect you for the rest of your life and often become progressively worse. Although there are drugs, which can help limit the impact of heart failure, there isn’t a cure at the moment.