Work of Heart
Read the Passage Carefully and answers the Following Questions: –
1The work of the heart can never be interrupted. The heart’s job is to keep oxygen-rich blood flowing through the body. All the body’s cells need a constant supply of oxygen, especially those in the brain. Brain cells live only four to five minutes after their oxygen is cut off, and death comes to the entire body.
2 The heart is a specialized muscle that serves as a pump. This pump is divided into four chambers connected by tiny doors called valves. The chambers work to keep the blood flowing around the body in a circle.
3 At the end of each circuit, veins carry the blood to the right atrium, the first of the four chambers. Its oxygen has been used up and it is on its way back to the lung to pick up a fresh supply and to give up the carbon dioxide it has accumulated.
4 From the right atrium, the blood flows through the tricuspid valve into the second chamber, the right ventricle. The right ventricle contracts when it is filled, pushing the blood through the pulmonary artery, which leads to the lungs. In the lungs, the blood gives up its carbon dioxide and picks up fresh oxygen. Then it travels to the third chamber, the left atrium. When this chamber is filled it forces the blood through the mitral valve to the left ventricle. From here it is pushed into a big blood vessel called aorta and sent around the body by way of arteries.
5 Heart diseases can result from damage to the heart muscle, the valves of the pacemaker. If the muscle is damaged, the heart is unable to pump properly. If the valves are damaged blood cannot flow normally and easily from one chamber to another, and if the pacemaker is defective the contraction of the chambers will become uncoordinated.
6 Until the twentieth-century doctors dared to touch the heart. In 1953 all this changed. After twenty years of work, Dr John Gibbon of the U.S.A. had developed a machine that could take over temporarily from the heart and lungs. Blood could be routed through the machine, bypassing the heart so that surgeons could work inside it and see what they were doing. The era of open-heart surgery had begun.
7 In the operating-theatre, it gives surgeons the chance to repair or replace a defective heart. Many patients have had plastic valves inserted in their hearts when their own was faulty. Many people are being kept alive with tiny battery-operated pacemakers; none of these repairs could have been made without the heart-lung machine. But valuable as it is to the surgeons, the heart-lung machine has certain limitations. It can be used only for a few hours at a lime because it’s pumping gradually damages the blood cells.
1. Circuit—tourney round a place. 2. Accumulated—gathered 3. Pacemaker—a kind of knob that makes the heart work rhythmically. 4. Takeover – take responsibility for something’. 5. Era—a period in history marked by an important event or development.
(a) On the basis of your reading of the above passage make notes on it, using recognizable abbreviations wherever necessary (minimum 4). Use a format you consider suitable. Supply an appropriate title to it.
(b) Make a summary of the passage in about 80 words.
(a) Notes on the contents of the Passage :
A.Work of the heart—
(i) can never be interrupted
(ii) keeps oxygen-rich blood flowing through the body
(iii) Without a constant supply of oxygen body’s cells–especially brain cells—die very soon.
B. Construction of the heart–a pump with four chambers
(i) right atrium
(ii) right ventricle
(iii) left atrium
(iv) left ventricle —The valves at each chamber help to keep the blood flowing around the body in a circle.
C. Heart Diseases result from—
(i) damaged muscles
(ii) damaged valves
(iii) damaged pacemaker
D. Work of Dr John Gibbon (U.S-A)
—developed the heart-lung machine
—made open-heart surgery possible
E. Uses of open-heart surgery/heart-lung machine
—insertion of a plastic valve in place of a faulty one
—insertion of battery-operated pacemakers
F. Limitations of the heart-lung machine
—can be used only for a few hours at a time
—damages the blood cells.
Heading: The Human Heart
(b) Summary of the Passage :
The heart has to work continuously without any interruption. It has to keep the oxygen-rich blood flowing through the body or else the body’s cells will die in no time. The heart is divided into four chambers which help in keeping the blood flowing around the body in a circle. Heart diseases result when any of its valves or muscles are damaged. As a result of the invention of the heart-lung machine, damaged valves can now be replaced and the battery pacemaker can be inserted to restore the rhythmic beats of the heart.