The heart is a hollow muscular organ in the middle of the chest that pumps blood around the body supplying cells with oxygen and nutrients. It does pumping without break. Its size is like our fist. It is divided into four chambers, to avoid mixing of O2 and CO2 mixed blood, the upper two part are called auricles and lower two ventricle. A muscular wall, called the septum divides the heart lengthwise into left and right.
A valve divides each side into two chambers-an upper atrium and a lower ventricle. When the heart muscles contract it squeezes blood through the atria and through the ventricles. Oxygenated blood from the lungs flows from the pulmonary veins into the left atrium, through the left ventricles and then out via the aorta to all parts of the body. Deoxygenated blood returning from the body flows from the vena cava into the right atrium through the right ventricle and then out via the Pulmonary artery to the lungs for reoxygenation. At the rest heart beats between 60 – 80 times a minute. During exercise or a time of stress or excitement the rate may increase to 200 beats a minute contraction and expansion of heart is called heart beats or pulse. Doctors by counting these beats of heart or pulse presumes the status of health.
