The heart that beats in every breast has nothing to do with emotions. Its a phenomenal work house, it pumps and beats regularly for perhaps for a centaury. It’s generates enough power in a day to
drive a truck 32km.It contracts about 7, 00,000 in a week and 2500 million times in a lifetime. It act’s like a delivery service that never stops, it sends oxygenated blood through 100
kilometers of blood vessel and back to dispose the waste, what other machines gives such a reliable service. For all its power its very small not bigger than a fist .Ask some one to place a hand
on the heart, and they will indicate the left side, but its wrong, the heart is in the center of the chest.
Until the 17th centaury doctors believed that the liver produced blood and the heart delivered it once only to various reservoirs. The heart works like a pump which has valves to make
sure that the blood flows in one direction. It’s sequence is controlled by a pacemaker, the sinuatrial node which is situated at the top of the right atrium. In three stages the heart draws in
blood and pumps it out. Its called diastole, arterial systole and ventricular systole. At each stroke the volume of blood must be matched equally. In a healthy heart this is finely
tuned.
The heart is shaped to cope with the delivery problem and avoid a build up of blood in one place and a shortage in another. The heart left side contract with greater force than the right, that is
why the heart is shaped as ii is, with more muscular bulk on its left side. No matter whether your heart beats at 200 times a minute, as it may if you exercise strenuously or at a mere one third of that when you are at rest it has to maintain a precise rhythm, also is has to be up to the mark wide variation in its output. When a person exercises his muscles demand more oxygen to supply the oxygen required the heart pumps more blood, as much as
50 liters a minute compared with about 6
liters when at rest .These changes are achieved in two ways, because it pushes out more blood the heart also receives more. The increase in this intake produces an increase in
output.
A nucleus of nerve cell located in the brain stem watches over the heart from which is known as the cardiac center. These nerves cell are part of the body automatic nervous system which
monitors a number of essential functions withought you having to worry about them. If you are at rest the heart rate
slows down, if you exercise it releases two hormones adrenaline and noradrenalin which increases the heart rate and the force of its contraction. A key measure to heart efficiency is its cardiac
output, the amount of blood it pumps in a given time. This depends on how fast the heart beats and the volume of blood ejected with each contractions. On average cardiac output is about 4.5liters a minute a staggering 8 tonnes
a day.
The heart is a strong muscle of a special kind, unlike any other in the body and perfect in design, one cannot make an artificial heart
that compares its performance with the natural organ. If the heart stops beating for as little as four minutes, its owner may die or suffer irreversible brain damage, that is why heart disease is
such a killer. Many of these deaths are premature adults’ aged 40-60 years with men of of this group four times
more likely to die than women. The Unites States has cut out deaths from coronary heart disease by a third. The
heart rate speed up with exercise sometimes as high as 220 beats per minutes. An electrocardiogram shows part of the pattern of a normal heart beat. This is made by monitoring electrical impulse that
immediately precedes the heart contraction.
By Randolph D’souza
ACSM Certified Personal Trainer.
Enter comment - View the 0 comments
