Our heart is a muscular organ about the size of a fist. It is located behind and left of the breastbone. Our heart is the main organ of the cardiovascular system, working hard to pump oxygen-rich blood to all the organs in our body. Besides delivering the nutrients, it also helps to carry away unwanted carbon dioxide and waste.
Read about common chest pains.
1. Our heart is made up of different layers of tissue
- Epicardium – The outer protective layer of the heart.
- Myocardium – The muscular middle layer wall of the heart.
- Endocardium – The inner layer of the heart.
These three layers are protected by a sac known as the pericardium, a thin outer lining protecting the heart.
2. Our heart has four chambers
- The right atrium receives blood from the systemic veins (carrying oxygen-depleted blood) and pumps it to the right ventricle.
- The right ventricle receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen.
- The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
- The left ventricle (the strongest chamber) pumps oxygen-rich blood to the rest of the body. The left ventricle’s vigorous contractions create our blood pressure.
3. Our heart has four valves
- They are like gatekeepers, keeping the blood moving in the correct direction.
- Aortic valve – Located between the left ventricle and the aorta.
- Mitral valve – Located between the left atrium and the left ventricle.
- Pulmonary valve – Located between the right ventricle and the pulmonary artery.
- Tricuspid valve – Located between the right atrium and the right ventricle.
4. Electrical system
For our heart to function normally, electrical signals are sent to the heart muscle to tell it when to contract and relax.
The electrical signal starts in the right atrium where your heart’s natural pacemaker, ‘the sino-atrial node’ is situated. This signal crosses the atria, making them contract. Blood is pumped through the (mitral and tricuspid) valves into the ventricles.
Where the atria meet the ventricles, there is an area of special cells – called the atrio-ventricular node – which transfers the electrical signals throughout your heart muscle by a system of electrical pathways, known as the conducting system.
The muscles of the ventricles then contract, and blood is pumped through the pulmonary and aortic valves into the main arteries.
The heart’s natural ‘pacemaker’ – the sino-atrial node – then produces another electrical signal, and the cycle repeats.
5. Blood pressure
Blood pressure is determined by the force against blood vessel walls as the heart pumps blood. Blood pressure changes every minute. It plays a vital role in the way our heart delivers blood through the blood vessels. Blood pressure can be affected by the relationship between four components:
- Our heart’s pumping action
- Size and elasticity of the blood vessels
- Thickness/viscosity of the blood itself
- Blood volume
One heartbeat is a single cycle in which your heart contracts and relaxes to pump blood. At rest, the normal heartbeat is approximately 60 to 100 times every minute, and it increases in certain situations (eg when you are exercising, having a fever or feeling anxious).
To ensure an adequate blood supply around your body, the four chambers of your heart have to pump regularly, in synchrony, and in the right sequence.
There are two phases to your heart’s pumping cycle:
- Systole: This is when the ventricle contracts, pushing blood out of the chambers
- Diastole: This is the period between contractions when the ventricles of the heart (myocardium) relaxes and these are re-filled with blood.
In conclusion, our heart plays a vital role. It has to ensure a continuous supply of oxygen and other nutrients to the brain and the other organs. Please take good care of your heart and always maintain a healthy lifestyle. Your heart will thank you for that.