Heart and Circulation

Blood Circulatory system in our body is a system of large and small elastic vessels which transports or conveys blood throughout the body parts. In one day, blood pumped through the heart of a normal healthy adult at rest reaches around 2,100 gallons.
Heart is the central organism of the cardiovascular system and it is located between the two lungs in the middle of the chest. Two-third part of the heart lies in the left of the breastbone and remaining one third in the right. Putting a hand on left side the chest, we can easily feel heartbeats on the left side of the rib cage because at that place, the bottom left corner part of the heart, that is somewhat tilted forward, comes nearest to the body surface. The heart of an adult is about the size of two clenched fists. Heart shape is conical and it weighs around 7 to 15 ounces, depends on the size and weight of the individual.
The human heart has four chambers:
• The right atrium and right ventricle.
• The left atrium and left ventricle.
The chamber walls are made of a special kind of muscle myocardium which contracts rhythmically under the stimulation of electrical currents. The left and right atria and the left and right ventricles are separated from each other by a muscle wall known as the septum. Blood returning from the body through the venous system enters into the heart through the right atrium, where it is collected and is then pumped to the right ventricle. Each time when the right ventricle contracts; it propels this collected blood, which is low in oxygen content, into the lungs; there it is enriched with oxygen. Pulmonary veins transfer the blood to the left atrium, which contracts and pass it to the left ventricle. The left ventricle, which is the main pumping chamber of the heart, ejects the blood.