Heart is one of the most important organ of entire human body which lies a little to the left side in the chest between the lungs. Our heart beats about 100,000 times, and sending 2,000 gallons of blood surging through our body.
It is about the size of a closed fist and weighs about 300 grams. It is covered with a membrane called pericardium whose inner side remains in touch with the heart. It is, in fact, a muscle which is filled with blood. This is called myocardium and the layer which remains in contact with the blood is called endocardium.
The heart is a hollow organ divided into four chambers. Two chambers are on the right side and two on the left, separated by a wall called septum which does not let the blood of the two sides mix. The upper tow chambers of the heart are called left and right atrium or auricle while the two lower chambers are called left and right ventricles. Valves are fitted between atriums and ventricles. These valves open only in one direction. The blood can go from atrium to ventricle but not form ventricle to atrium.
Heart works as a powerful pump and sends blood to the whole body. Its two sides work together. They pump blood through the two chambers at the same time. The right side pumps impure blood to the lungs. The left side pumps purified blood to all other parts of the body.
Heart Beat: The heart beats automatically. It does not need to be controlled by the brain. Heart beat corresponds to the circulation of blood. Every heart beat has three stages. They are Contraction of the two Atriums, Contraction of the two Ventricles and the Rest period.
One heart beat completes one cardiac cycle. Heart beats can be heard by putting the ear onto the left side of the chest or with the help of a stethoscope. The count of heart beats of anew born child goes to about 140 per minute. A ten years old child heart beats about 90 times a minute. In a healthy adult, it varies from 70 to 72 times per minute while a woman’s heart beats 78 to 82 times a minute. During exercise, the beats rate goes as high as 140 to 180 per minute. If a person’s heart beat is not up to the proper count, an external device----pacemaker---is implanted to regularize it.
Inside The Human Heart
The Heart Supplies Pure Blood To The Body