Our wonderful heart
Our heart starts working non stop even before you are born! It is a wonderful pump which beats a little faster than once every second. To be exact, the normal heart beats about 60 to 100 times every minute, pumping blood to all parts of the body. Its function is so vital that the brain stops functioning within minutes of a cardiac arrest.
Heart pumps around five litres of blood every minute in a resting person, though it is sized only about that of your own fist. It is situated in nearly in the centre of the chest, more towards the left. Four chambers of the heart are arranged obliquely, unlike the familiar square diagram which we learn at school. It is so oblique that the left sided chambers are mostly towards the back of the right sided chambers. The left upper chamber is named left atrium (or auricle) and left lower chamber is called the left ventricle. They receive oxygen enriched blood from the lungs, looking bright red. Left atrium receives the blood from the veins of the lung (pulmonary veins) and empty into the left ventricle through the mitral valve. Mitral valve is the valve between the left atrium and the left ventricle, named so because it resembles the mitre or the head wear of a bishop. When the left ventricle contracts, the mitral valve closes, preventing blood from flowing back into the left atrium. Left ventricle pumps its blood into the aorta, the largest blood vessel in the body carrying oxygenated blood. Aortic valve prevents backflow of blood from aorta to the left ventricle. Branches of the aorta take blood to various parts of the body.
The right sided chambers of heart carry deoxygenated blood (blood with low oxygen content) returning from various parts of the body. Upper right sided chamber is called the right atrium (or auricle). The three important vessels draining into the right atrium are the superior vena cava, inferior vena cava and coronary sinus. Superior vena cava is a large blood vessel draining deoxygenated blood from head, neck and upper limbs. Coronary sinus drains blood returning from the heart. As heart works continuously at full steam, coronary sinus blood has the lowest oxygen level among all the blood vessels of the body. Inferior vena cava drains blood from the lower part of the body and lower limbs.
Right atrium empties its blood into the right ventricle through the tricuspid valve, which prevents backflow of blood when the right ventricle contracts. Right ventricle pumps blood to the lungs through the pulmonary artery, which is guarded by the pulmonary valve to prevent back flow. Lung oxygenates the blood and returns it to the left atrium through pulmonary veins.