How Your Heart Works
Your heart is a muscle about the size of a clenched fist. It lies in the centre of your chest between your breastbone and spine.
The heart is a very strong and efficient muscular pump. Its job is to keep blood supplied to all parts of the body. It pumps about 5 litres of blood per minute.
How does my heart work?
There are 2 sides to the heart, left and right, both act as pumps.
The two sides are further divided into 2 chambers, giving 4 chambers in total.
The upper chambers are called ATRIA: they collect blood.
The lower chambers are called VENTRICLES: they contract to pump the blood out.
The left side of the heart is larger than the right and pumps blood, rich in oxygen and nutrients, through blood vessels called arteries to the body.
The oxygen is used by the body, and the veins carry the blood, now low in oxygen, back to the right side of the heart.
The right side of the heart then pumps this blood to the lungs where it receives more oxygen
This blood returns to the left side of the heart and is pumped around the body again.
Blood is pumped at high pressure to get to all the body’s parts. For this to happen, the heart has to be very strong and needs a very good blood supply. This is provided by the coronary arteries and their branches.
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What are coronary arteries?
The coronary arteries branch from the aorta which is the main artery taking blood away from the heart to the rest of the body.
They are the first to receive the blood which is rich in oxygen.
The 2 coronary arteries pass around the heart, meet at the back and almost form a circle.The left coronary artery and its branches supply blood to most of the left ventricle. The left ventricle is the more muscular and larger of the two ventricles, as it has to do the hard work of pumping blood all around the body. The right coronary artery is usually smaller and supplies the right ventricle and the underside of the heart.
What is coronary artery disease?
In coronary artery disease, the coronary arteries become narrowed, starving the heart muscle of the blood and oxygen it needs. The narrowing process is known as atherosclerosis
What is a normal heart rhythm?
The heart has its own electrical conduction system, which allows impulses to travel through the heart’s muscles causing them to contract and pump blood around the body.
The electrical impulse is produced by a special part of the right atrium (the top chamber) called the sinus or sinoatrial (SA) node. This is frequently called the hearts natural "pacemaker".
The electrical impulse travels from the SA Node through the muscle of the atriums causing them to contact and push the blood into the ventricles, the lower chambers.
The impulse then comes to the atrio-ventricular node or AV node.
The AV node acts like a junction box and the impulse is delayed momentarily before it enters the muscles of the ventricles via fibres which act like wires. This is known as the Purkinje fibres
· As the impulse travels along these fibres, the ventricles both contract, pushing the blood out of the heart to the lungs and body.
· These impulses make the heart beat 60-100 times every minute.
· Sometimes our heart beats faster or slower depending on how healthy we are and whether we are exercising or resting.
· Occasionally things go wrong with the electrical system of the heart. This results in an irregular heartbeat is called an arrhythmia.