Question

Give an account of working of the human heart.

Answer 1

Hint: The human heart is an organ that through the circulatory system, pumps blood across the body, supplies tissue with oxygen and nutrients, and eliminates carbon dioxide and other waste.

Complete answer:
The heart is a muscular organ that in the body continuously pumps blood. Four chambers are composed of the right and left atrium and the right and left ventricles.
By alternately contracting and relaxing to pump blood around the heart, the chambers of the heart function together. The heart uses an electrical mechanism to activate a heartbeat in order to do this. Essentially, the power source that makes all the activities of the heart possible is the electrical system.
In and out of the chambers, which receive and disperse blood throughout the body, blood vessels lead. Four valves, the tricuspid, pulmonic, mitral and aortic valves, connect the four chambers. These valves act like one-way doors, allowing only one path for blood to flow.

Circulation of Blood
As the heart beats, it pumps blood into a blood vessel structure called the circulatory system. For the body to work, the blood that these vessels carry is essential. Blood delivers oxygen and nutrients to the tissues of the body, helps eliminate carbon dioxide and waste products and improves the overall health of the tissues of the body. There are three main vessel types which make up this system:
1.Arteries,
2.Veins
3.Capillaries
Via two broad veins, the inferior and superior vena cava, blood enters the heart and empties into the right atrium. It flows into the right ventricle through the tricuspid valve from the right atrium. Via the pulmonic valve, the blood then leaves the right ventricle and heart and flows into the pulmonary artery and lungs. Via the pulmonary vein, oxygenated blood returns to the left atrium from the lungs to the heart.Blood passes through the mitral valve to the left ventricle from the left atrium. Blood exits the heart from the left ventricle through the aortic valve and travels to the aorta and to the body.

Coronary arteries
The heart muscle is used to efficiently pump its own supply of oxygen and nutrients. The heart derives no nourishment from this blood, while its chambers are full of blood. The heart, through a network of arteries known as the coronary arteries, receives its own blood supply.

Function of right and left coronary arteries:
Coronary arteries curl around the heart's surface. The two major coronary arteries branch out from the aorta, the right coronary artery and the left coronary artery. The right atrium and right ventricle are supplied by the right coronary artery. It branches into the descending posterior artery. The left coronary artery branches into the artery of the circumflex and the descending anterior left artery. The left atrium and the left ventricle are supplied by the left coronary artery.

Narrow Coronary arteries,
A network of tiny blood vessels that normally remain inactive is collateral circulation. Collateral vessels become swollen and active when coronary arteries narrow to the point where blood flow to the heart is limited. This process enables blood flow to the heart muscle around the blocked artery.

Note: 1.The heart of a person is approximately the size of a large fist.
2.The heart weighs between 280 and 340 grammes (approximately 10 to 12 ounces) in men and 8 to 10 ounces (230 to 280 grammes) in women.
3.About 100,000 times a day the heart beats (about 3 billion beats in a lifetime).