How Does the Heart Work?
The heart, which is a muscular pump, beats about 72 times a minute through a continuous and automatic process of muscular contraction and relaxation. It is about the size of a fist, weighs about 9-11 ounces and is placed snugly between the lungs, a little more to the left than to the right.
A partition runs down the centre of the heart, dividing it into left and right sections which work at the same time but deal with two different types of blood. Each section is again divided into upper and lower parts, the auricles and ventricles. The blood is pumped through all four chambers in turn in the course of being circulated through all parts of the body.
The heart’s first purpose is to supply a steady flow of oxygen to all the body cells and to return carbon dioxide to the lungs. On its journey the blood distributes dissolved foods and carries away wastes.
Two large veins pour the dark, used blood into the first chamber, the right auricle, which passes it into the chamber below, the right ventricle. The muscle surrounding this part contracts in a beat that pushes the blood into the lungs where the carbon dioxide is removed and replaced with vital oxygen.
Meanwhile fresh scarlet blood from the lungs enters the left auricle to be transferred to the left ventricle. From there it is forced by the contracting muscle through a valve into the aorta, the body’s largest artery which distributes it all over the body.
The heart beats about 1, 00,000 times every 24 hours and pushes several quarts of blood through miles of arteries, veins and capillaries. A healthy heart keeps this up for a lifetime without faltering.
Cardiovascular diseases (CVD) are the most common cause of death globally as of 2008, accounting for 30% of deaths, of these more than three quarters are a result of coronary artery disease and stroke. Risk factors include: smoking, being overweight, little exercise, high cholesterol, high blood pressure, and poorly controlled diabetes, among others.
Cardiovascular diseases frequently have no symptoms or may cause chest pain or shortness of breath. Diagnosis of heart disease is often done by the taking of a medical history, listening to the heart-sounds with a stethoscope, ECG, and ultrasound. Specialists who focus on diseases of the heart are called cardiologists, although many specialties of medicine may be involved in treatment.