Human heart and its function

Heart is the most vital organ with most vital function of our body. In simple, the heart is a chambered muscular organ and located in between left and right lung of human body under rib-cage. The heart pumps blood through the blood vessels of the circulatory system by rhythmic contraction and dilation. It maintains the continuous flow of blood through the entire circulatory system.

The heart contains four chambers, two upper atria, (called left and right atrium) connected to the veins that carry blood to the heart, are the receiving chambers. And other two chambers, the lower ventricles (called left and right ventricle), the discharging chambers, connect to the arteries for supplying blood.

The right part of heart has of two chambers, the right atrium and the right ventricle, separated by a valve called tricuspid valve. Tricuspid valve controls flow of blood. These chambers circulates blood through the lung.

The left heart consists of two chambers, the left atrium, and the left ventricle, separated by the mitral valve. This part of heart pumps blood to the entire body through circulatory system.



The heart circulates blood mainly by two types of circulation called systemic circulation and pulmonary circulation.

Systemic circulation:

In systemic circulation, the heart pumps oxygenated blood away from the heart through the aorta(aorta is the main artery of human body, originating from the left ventricle of the heart and further splits into two smaller arteries), from there blood enters the arteries and capillaries, finally supplies the body’s tissues with oxygen and returns oxygen-depleted blood back to the heart via veins.

Pulmonary circulation:

In pulmonary circulation, heart pumps blood with carbon dioxide to lungs via the pulmonary artery and exchange carbon dioxide with oxygen in lungs and oxygenated blood re enters to the heart through pulmonary veins.

Circulation through the heart

The heart collects blood low in oxygen from the systemic circulation, which enters the right atrium via superior and inferior venae cavae and passes to the right ventricle through tricuspid valve. From there blood is pumped into the pulmonary circulation via the pulmonary artery, through the lungs where it gives off carbon dioxide and receives oxygen. Oxygenated blood then enters to the left atrium via the pulmonary vein, travels through the left ventricle via  the mitral valve. And the heart pumps oxygenated  blood out through the aorta and to the body cells through arteries.

The heart is made up highly specialised cardiac muscle and covered by membrane. It has three layers, the pericardium or outermost layer, the myocardium (muscle layer) or middle layer and the endocardium or inner lining.

Like other organs of the body, heart is also in a form of muscle, needs oxygenated blood to survive. The circulation of blood by which the heart receives oxygen rich blood and expels deoxygenated blood, called coronary circulation.

The aorta (the main blood supplier to the body) branches off into the left and right coronary arteries that run on the surface of the heart, spread into smaller arteries, which supply oxygen-rich blood to the entire heart muscle through left and right side of heart.


And cardiac vain collects deoxygenated blood from the heart and passes blood to the right atrium through the coronary sinus and finally returns to lungs in pulmonary circulation.

Bottom line

These are continuous circles of human body in which heart acts as pump. With its continuous action it pumps around 6-7 L/min of blood in normal range through more than 60000 miles of tiny blood vessels of our body.

It is used to be thought that normal heart rate at resting is in between 60-100 beats per minute (bpm) depending upon age and gender. Many experts believe resting heart rate in between 60-80 bpm is more healthy level. An individual with better physical fitness level and having better heart muscle may have lower resting heart rate. An athlete having stronger heart muscle may have resting heart rate closer to 40bpm.  On the other side a less active person may have higher resting heart rate than a normal because the heart muscle has to work harder to maintain bodily functions, making it higher.



Bikramjit Konwar

Author: Bikramjit Konwar


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