IELTS Academic Reading Practice Test 310

For more than a thousand years the teaching of the Greek physician Galen shaped European ideas about the body. Galen held that blood was made in the liver from digested food and then carried to the heart, which distributed it through the body; there the blood was used up by the tissues. Blood, in his account, did not travel in a closed circuit. It moved outwards through the arteries and ebbed back through the veins, and some passed from one side of the heart to the other through invisible pores in the wall between them. So great was Galen's authority that few physicians thought to test these claims.

William Harvey was born in Folkestone, on the Kent coast, in 1578, the eldest son of a prosperous merchant. He studied at Gonville and Caius College, Cambridge, and then at Padua, the most admired medical school in Europe, where he took his doctorate in 1602. One of his teachers there was Hieronymus Fabricius of Acquapendente, who had written about the small flaps of tissue inside the veins. Fabricius assumed that these structures, now called valves, existed to slow the blood and stop it collecting in the limbs. Harvey eventually reached a very different conclusion.

Returning to England, Harvey built a large and lucrative practice. He became a fellow of the Royal College of Physicians and later served both James I and Charles I. His position at court brought practical advantages: he was allowed to dissect animals from the royal parks, and the king is said to have supplied him with deer for his experiments. Harvey insisted throughout that what could be seen with the eye should outweigh what ancient writers had merely asserted.

His central argument rested on arithmetic. Harvey estimated the volume of blood held in the heart's chambers and multiplied it by the number of beats in an hour. Even on cautious assumptions the total was extraordinary: he calculated that the heart expelled more blood in half an hour than the whole body contained. The liver could not manufacture such a quantity from food, and the tissues could not consume it. The only reasonable explanation was that the same blood returned to the heart and was pumped out again — a proof by quantity that blood must move in a circle.

Simple experiments supported the case. When Harvey tied a band tightly around a volunteer's arm, the veins beyond it swelled and the valves appeared as small knots beneath the skin. Pressing blood along a vein with a finger, he found that it would not pass the next valve; when he released the pressure, the blood ran back. He also cooled the hearts of snakes and frogs until they beat slowly enough for each contraction to be observed, and he opened living animals to watch the heart move. The heart, he concluded, was a muscle that squeezed blood out as it contracted.

In 1628, at the age of fifty, Harvey published his conclusions in a short book of some seventy pages, printed in Frankfurt and usually known in English as On the Motion of the Heart and Blood. Harvey states that the blood circulates, that the heart acts as a pump, and that the pulse felt at the wrist is caused by arteries filling as the heart empties. He notes, too, that the valves in the veins all point towards the heart, so that they permit flow in one direction only.

Reaction was mixed. Some physicians were persuaded quickly, and the philosopher René Descartes endorsed the new account. Others were hostile, seeing an attack on Galen as an attack on the foundations of medicine, since the common treatment of bleeding depended on the old theory of how blood was made and used. The Paris anatomist Jean Riolan the Younger defended Galen at length, and Harvey answered him in a second, shorter treatise published in 1649.

One problem remained. Harvey could not see how blood passed from the smallest arteries into the smallest veins, and admitted that he could only suppose the existence of passages too fine for the instruments of his time. He was right to be confident. In 1661, four years after his death, the Italian anatomist Marcello Malpighi examined the lungs of a frog under one of the new microscopes and saw the tiny vessels that join the two systems, which were later named capillaries.

Harvey did not abandon research. In 1651 he published a long study of reproduction, On the Generation of Animals, arguing that every animal develops from an egg, a claim not fully confirmed for another two centuries. He had retired from practice by then, and he died near London in 1657.

The circulation of the blood became one of the foundations on which physiology was built. Harvey's method mattered as much as his conclusion: he took a mass of ordinary observations, showed that they pointed to a single explanation, and was willing to follow the evidence against the most respected authority of his age.

The heart is usually described as a single organ, but it works as two pumps that share a shell of muscle. The right side receives blood returning from the body and pushes it to the lungs, where it takes up oxygen; the left side collects that oxygen-rich blood and drives it out to the tissues. Each side has an upper chamber, the atrium, which fills first, and a lower chamber, the ventricle, whose contraction provides the force. A muscular wall called the septum separates the two sides so that the two streams do not mix. The wall of the left ventricle is much thicker than that of the right, because it must generate enough pressure to reach the whole body.

Four valves keep the flow moving in one direction. The tricuspid valve sits between the right atrium and the right ventricle, and the pulmonary valve guards the exit from the right ventricle into the pulmonary artery. The mitral valve, which has two leaflets, lies between the left atrium and the left ventricle, while the aortic valve controls the opening into the aorta, the great artery that carries blood to the body. Each valve opens when pressure on one side exceeds pressure on the other, and closes when the flow tries to reverse. There is no muscle inside a leaflet: the cusps are moved by the blood itself.

A leaflet is a thin sheet of connective tissue, stiffened by collagen and elastic fibres and covered by a smooth layer of cells. Its task is to let blood pass and then to seal, so that nothing leaks back into the chamber it has just left. Because a leaflet contains no blood vessels of its own, it is nourished by the blood flowing past and cannot mount the swelling and repair response that other tissues produce when injured. The mitral and tricuspid valves are held in place by tough cords, the chordae tendineae, which run from the free edges of the leaflets to small muscles in the ventricle wall.

Valves form early in development, from cushions of tissue inside the embryonic heart that are reshaped by the blood flowing over them. Occasionally the process goes slightly wrong. The commonest congenital heart defect is a bicuspid aortic valve, in which two leaflets form instead of the usual three, and it affects roughly one or two people in a hundred. Many of them never learn that they have it, because the valve works well for decades. In some, however, the abnormal shape places extra mechanical stress on the tissue and leads to trouble in middle age.

The commonest valve disease in older people is aortic stenosis, a narrowing caused by the gradual build-up of calcium deposits on the leaflets. The process resembles the formation of bone, and it stiffens the valve until it can no longer open fully. The heart must then work harder, and its muscle thickens in response. At first there may be no symptoms; later, people notice breathlessness on exertion, chest pain or dizziness, and fainting can follow. Once severe stenosis produces symptoms, the outlook without treatment is poor.

A narrowed valve usually produces a murmur, a rushing sound that a doctor can hear through a stethoscope. The decisive test today is echocardiography, which uses ultrasound to show the leaflets moving and to measure the speed of blood across them, and so allows the cardiologist to judge how tight the opening has become. Computerised tomography is increasingly used as well, because it reveals calcium in the leaflets and helps in planning a procedure.

Until the middle of the twentieth century a badly damaged valve could not be replaced; from the 1960s, surgeons began removing diseased valves and inserting artificial ones. Two kinds of substitute are now in use. Mechanical valves, made of metal or carbon, are extremely durable and seldom wear out, but they encourage clotting, so anyone who receives one must take anticoagulant drugs for the rest of their life. Tissue valves, usually made from animal tissue treated to prevent rejection, avoid this medication, but they deteriorate over time, particularly in younger patients.

The most important change in recent years has come from a different direction. In 2002 a team in France carried out the first transcatheter implantation, in which a replacement valve, folded inside a narrow tube, is passed through an artery in the groin to the heart and expanded in place. The procedure avoids opening the chest and can be done under local anaesthetic, so it suits patients who are too old or too frail for surgery. Trials have since extended it to people at lower surgical risk, and in many hospitals it is now the standard treatment for older patients with aortic stenosis.

Uncertainty remains about how best to use these techniques. A tissue valve inserted by catheter may not last as long as one sewn in during open surgery, and because transcatheter replacement is now offered to younger patients, many of them will need a second procedure later in life. It is also unclear whether people whose stenosis is only moderate should be treated before symptoms appear. In low- and middle-income countries, meanwhile, rheumatic heart disease, caused by an untreated streptococcal infection in childhood, remains a common cause of valve damage.

Valves are simple in principle and difficult to replace in practice, and the search for a substitute that lasts a lifetime without drugs continues.

Every year thousands of people with failing kidneys, livers or hearts wait for an organ that may never arrive. In most countries the supply depends on individuals recording their willingness to donate after death, yet the distance between what the public says and what it does is striking: large majorities tell surveyors that they would be glad to donate, while the proportion who have registered is far smaller. Campaigners for presumed consent argue that this gap reflects inertia rather than opposition, and that a law which waits for people to find time to sign a form will always lose organs that could have been used.

Two legal models exist. Under an opt-in system, organs may be taken only from those who have expressly agreed, either by joining a register or by telling their families. Under an opt-out, or presumed consent, system, every adult is treated as a potential donor unless an objection has been recorded during their lifetime. Most opt-out countries operate a soft version, in which relatives are still consulted and may refuse. The United Kingdom has moved part of the way: Wales adopted a soft opt-out in 2015, England in 2020 and Scotland in 2021.

The strongest argument for presumed consent is about defaults. Wherever a decision requires effort, some people will fail to make it, and the result will be decided by whatever happens when they do nothing. The clearest illustration comes from outside medicine. When automatic enrolment into workplace pensions was introduced in the United Kingdom, the share of eligible employees saving rose sharply, not because people had changed their minds but because the default had changed. An opt-out law for donation might save lives in the same way, simply by making inaction work in the other direction.

The experience of Spain is usually cited in support of this view. Spain has long recorded one of the highest rates of deceased donation in the world, close to forty donors for every million people, and it has had an opt-out law since 1979. Yet donation rates changed little for a decade after the law was passed; they rose only after 1989, when Spain created a national network of hospital-based transplant coordinators, which is widely credited with producing the result. Presumed consent may have helped, but it is hard to describe it as the cause.

Sceptics who compare countries make a similar point from a different direction. Comparing countries, they observe, does not give a clear answer, because several states with opt-out laws on their statute books have donation rates no better than those that rely on express consent: the law on paper is not the law in the hospital. Legislation that arrives without money for coordinators, intensive care beds and public information can therefore change almost nothing. On this reading, the priority is not the default but the system around it.

There is, however, an objection that cannot be answered with statistics. Consent that is assumed is not consent that is given, and the point is made most forcefully by those who observe that silence is not agreement: someone who has never heard of the register has not, by failing to object, agreed to anything. The concern is sharper for groups who already have reason to distrust assurances about their bodies, and families from some minority ethnic communities are known to be more likely to refuse consent.

For this reason the details of the law matter as much as its principle. In a soft opt-out the relatives are still asked, and in practice their refusal is almost always respected, even when the deceased had recorded no objection. Some campaigners see this as a loophole; those who defend the family veto, among whom I count myself, see it as a safeguard. Overruling a bereaved family would save a few more organs, but it would also confirm the fear that presumed consent means the state taking whatever it wants.

If money is to be spent, it should be spent on coordinators. Their job is to identify possible donors in the intensive care unit and to talk to families in the worst hours of their lives, and the quality of those conversations does much to determine whether a family says yes. Coordinators insist that their work, rather than the wording of any statute, explains most of the variation between hospitals. Where donation rates have risen, it has generally been in systems that invested in such staff.

My own view is that the case for an opt-out is sound but modest. Because the evidence does not show that legislation on its own raises rates very much, the reform should be presented honestly, as one element of a wider programme rather than as a solution. It should come with money for coordinators, an objection that is easy to register, and a promise that a family's refusal will be respected. On those conditions the change is defensible: it shifts the default towards generosity while leaving the final say with the people who knew the deceased best.

The question, after all, is not whether consent should be presumed, but which arrangement wastes fewer organs without taking anything that was not offered.