How Does The Heart Pump Blood?

The heart's lower two chambers, the right and left ventricles, serve as powerful pumping stations. These ventricles pump blood into arteries, blood vessels that take away blood from the heart. The two sides pump blood through a different circuit of blood vessels: The right side pumps oxygen-poor blood to the lungs, while the left side of the heart propels oxygen-rich blood to the body. During it trip from and to the heart blood gives up most of its oxygen and collects carbon dioxide. This oxygen-deficient blood feeds into two large veins, the superior vena cava and inferior vena cava, which drain into the right atrium of the heart. The right atrium transfers blood to the right ventricle, and the right ventricle propels blood into the pulmonary artery. The pulmonary artery takes the blood to the lungs, where it gets a fresh supply of oxygen and eliminates carbon dioxide.

The blood which has now become oxygen-rich returns to the heart through the pulmonary veins, which drain into the left atrium. Blood then passes from the left atrium into the left ventricle, from where it is thrust out of the heart into the aorta which is the body's largest artery. Smaller arteries that emanating from the aorta distribute blood to various parts of the body.

The heart lies at the centre of the circulatory system which consists of network of blood vessels that carries blood to every pore of the body. Heart is a muscular pump which pumps blood continuously through the circulatory system. On an average it beats about 100,000 times in a day.

The blood in the heart is pumped through four chambers. The upper is called atria and lower ventricles. Each has a left and right side and is connected by valves. The right side of the heart receives oxygen depleted blood and pumps it to the lungs where carbon dioxide is released and oxygen inhaled. The left side receives this oxygen rich blood which is further circulated to the body. Hence the left ventricle is large and strong to be able to pump blood to whole body.

In a normal healthy heart all four chambers function continuously in a well coordinated manner. The heart beat is governed by an electric impulse. A discharge from this natural pace maker causes the muscles to relax and contract. The muscles of the four chambers relax to fill with blood and then contract so that blood is pumped out. When each chamber contracts, the valve opens to allow blood from right atrium to right ventricle and left atrium to left ventricle and when it relaxes the valve closes to prevent blood from flowing back.

The electric impulses are generated at specific rate but hormonal changes, emotional ups and downs and exercise can alter the rate and hence the heart beat.

All four chambers are in an organised beat made by an electrical impulse.the signal is made in thr right atrium.

In a nutshell your heart has a series of one way valves.  As the heart muscle contracts it pushes blood out of the heart in only one direction and when it relaxes it expands and draws it back in through the other one way valves.

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