Medicine is the science and art of healing. Medicine is a science because it is based on knowledge gained through careful study and experimentation. It is an art because it depends on how doctors and other medical workers apply this knowledge when dealing with patients. The goals of medicine are to save lives, relieve suffering, and maintain the dignity of ill individuals. For this reason, medicine has long been one of the most respected professions.
Many thousands of men and women who work in the medical profession spend their lives caring for the sick. When disaster strikes, hospital workers rush emergency aid to the injured. When epidemics threaten, doctors and nurses work to prevent the spread of disease. Researchers continually search for better ways of fighting disease. Human beings have suffered from illnesses since they first appeared on the earth about 21/2 million years ago. Throughout most of this time, they knew little about how the body works or what causes disease. Treatment was mainly based on superstition and guesswork.
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Medicine has made tremendous progress in the last several hundred years. Today, it is possible to cure, control, or prevent hundreds of diseases. People live longer than they did in the past due to new drugs, machines, and surgical operations. In addition, medical progress in controlling infectious diseases, improvements in health care for mothers and children, and better nutrition, sanitation, and living conditions have given people a longer life expectancy. In 1900, most people did not live past the age of 50. Today, people in the industrial world have an average life span of about 75 years.
As medicine has become more scientific, it has also become more complicated. In the past, doctors cared for patients almost single-handed. Patients received treatment at home for most kinds of illnesses. Today, doctors no longer work by themselves. Instead, they head medical teams of nurses, laboratory workers, and many other skilled professionals. The care provided by such teams cannot generally be started at home. As a result, health centres, clinics, and hospitals have become the chief centres for medical care.
Medical care is often considered part of the larger field of health care. In addition to medical care, health care includes the services provided by dentists, clinical psychologists, social workers, physiotherapists, occupational therapists, and other professionals in various fields of physical and mental health. This article deals chiefly with the kind of service provided by doctors and other medical team members. Information about other kinds of health care can be found in separate World Book articles, such as CLINICAL PSYCHOLOGY; DENTISTRY; OPTOMETRY; and CHIROPODY.
Elements of medical care. Medical care consists of three main elements: (1) the diagnosis, or identification, of disease or injury; (2) the treatment of disease or injury; and (3) the promotion of health and prevention of disease. Diagnosis. Doctors use three main types of “clues” in making a diagnosis: (1) the patient’s case history, (2) the doctor’s physical examination of the patient, and (3) the results of medical tests. Patients provide their medical history by answering questions about their physical condition and past illnesses. Doctors use specific essential tools and techniques to perform a physical examination.
For example, they use a stethoscope to listen to a patient’s heart and lungs. Then, by pressing and probing various body areas, they check internal organs for unusual hardness, softness, or changes in size or shape. A lighted instrument called an endoscope allows doctors to see the interior of hollow organs, such as the stomach or intestines. Doctors also insert medical instruments through endoscopes to obtain pieces of tissue for study.
Medical laboratories aid diagnosis by making chemical and microscopic tests on body fluids and tissues. A doctor may also order tests that use radioactive trace elements, X rays, or sound or electric waves to detect disease by literally looking inside the body (see ULTRASOUND; X RAYS). To make a final diagnosis, the doctor fits all the clues from the patient’s case history, physical examination, and medical tests. If the diagnosis is complicated, the doctor may ask the opinion of other experts.
Treatment. People usually recover from minor illnesses and injuries without special treatment. In these cases, doctors may simply reassure their patients and allow the body to heal itself. But serious ailments generally require special treatment. In these cases, a doctor may prescribe drugs, surgery, or other treatment.
For thousands of years, drugs and surgery have provided two of the chief methods of treating disease. But modern science has helped make these methods much more effective than they used to be. Penicillin and other “wonder drugs” help cure many infectious diseases that were once extremely difficult to treat. With the help of machines, surgeons can repair or replace organs that have been seriously damaged, including the heart and kidneys. Science has also helped develop entirely new methods of treatment.
Radiotherapy, for example, makes use of X-rays and radioactive rays to treat cancer. Prevention. Doctors help prevent disease in various ways. For example, they give vaccinations to guard against such diseases as polio, hepatitis, and measles. They may also order a special diet or drug to strengthen a patient’s natural defences against illness. People can also help themselves remain healthy by exercising, not smoking, and by avoiding the use of alcohol or illegal drugs.
Doctors can prevent many diseases from becoming severe by diagnosing and treating them in their early stages. For this reason, most doctors recommend regular physical examinations. Screening programmes can diagnose commonly occurring diseases such as tuberculosis. In addition, screening programmes are used for diseases that carry a high risk of death.
They are used with groups that are especially at risk of contracting the diseases. For example, target groups for breast cancer are women aged between 50 and 65 years of age and younger women who have a high incidence of breast cancer in the family. See DISEASE (Preventing disease). In addition, local governments help prevent disease by enforcing public health measures. For example, they make sure the community has pure drinking water and a rubbish and sewage disposal system.
They are providing medical care. In industrial countries, high-quality medical care is available to most people when they need it. These countries include Australia, New Zealand, Canada, Japan, the United States, and most European nations. However, certain developing countries of Africa, Asia, and Latin America lack adequate facilities for high-quality medical care. Some of these countries have only one doctor for every 20,000 to 60,000 people. Some industrial countries, on the other hand, have one doctor for every 450 people.
In case of illness or injury, people need someone to diagnose their condition and prescribe or give the necessary treatment. This kind of basic health care is called primary medical care. It is provided by such doctors as general practitioners to whom people can go directly without being referred by another doctor or medical worker. However, if a case is complicated or severe, the person who provides primary medical care refers the patient to a doctor or a hospital or other institution that provides specialized care.
The role of the doctor. Doctors have detailed knowledge of the human body and how it works, and they are specially trained in the diagnosis, treatment, and prevention of disease. For this reason, they take responsibility for making all major decisions regarding the care of patients. Doctors who provide medical care can be divided into two groups: (1) general practitioners and (2) specialists. General practitioners provide primary medical care only. But they treat a wide variety of ailments. They provide care for every member of the family, regardless of the ages of those family members.
Specialists. In the past, almost all doctors were general practitioners. But medical knowledge has increased so rapidly during the 1900s that no doctor can possibly keep up with all the important advances. As a result, many doctors today specialize in a particular field of medicine. Neurologists, for example, specialize in diseases of the nervous system. Pediatricians specialize in children’s diseases. The section Improving the quality of medical care (The specialties) describes the major medical specialties.
Advances in medicine and technology have led to the growth of medical specialties. Seriously ill patients, especially, receive much more effective treatment than ever before. But as more and more doctors become specialists, fewer doctors may be available for primary medical care. The role of medical workers. Doctors could not do their job without the help of many other skilled professionals. Registered nurses, for example, work closely with doctors in clinics, hospitals, and medical centres.
Nurses also provide many services to patients independent of doctors. Pharmacists dispense prescriptions and give advice on the drugs prescribed. Various kinds of therapists give special treatment as ordered by the doctor. Other skilled workers serve in clinics, medical laboratories, X-ray departments, and operating theatres. The jobs of various kinds of medical workers are described later in this article.
Where medical care is provided. In the doctor’s surgery. Most doctors who provide primary medical care have a surgery-based practice. In their surgeries, they examine patients and, based on the findings, provide treatment. Primary-care doctors practise alone or in a group practice, where two or more doctors share the same clinic, equipment, and personnel. Group practice reduces each doctor’s expenses. It also enables doctors to offer more services under the same roof.
In hospitals. Hospitals offer services not available anywhere else. Patients receive round-the-clock care from a full-time staff of doctors, nurses, and other skilled workers. Teaching hospitals, where a great deal of medical research and education are carried out, are usually well equipped and offer advanced standards of care. The most advanced hospitals may have heart-lung machines, which can take over the work of a patient’s heart and lungs during a heart operation, and CT scanners, which can pinpoint damage or cancer in a patient’s brain.
Many hospitals have intensive care units, which use electronic monitoring devices to keep constant watch over seriously ill patients. The units are also equipped with highly technical life-saving equipment. For more information about the various kinds of hospitals and the services they provide, see HOSPITAL. In clinics. Clinics provide primary medical care for outpatients–that is, for patients who are not hospitalized. Some clinics are part of a hospital. Other clinics are run by doctors in a group practice or by community organizations.
Some clinics have both specialists and general practitioners on their staff. Others have specialists only. Many communities have certain types of specialized clinics, such as those that diagnose and treat diabetes, psychiatric disorders, sexually transmitted diseases, or AIDS (Acquired Immunodeficiency Syndrome). In nursing homes. Many nursing homes have professional nurses on the staff. They accept patients who need round-the-clock care but do not need to be hospitalized. Doctors visit the patients on a regular basis.
Many nursing homes are privately owned. In the home. Some people need continuing medical attention but not the round-the-clock care is given in hospitals and nursing homes. Various health service and local authority agencies and some hospitals sponsor domiciliary (home) care programmes for these people. The programmes offer certain types of therapy and nursing care.
Improving the quality of medical care. The role of medical organizations. A number of national and international organizations work to improve the quality of medical care. These organizations encourage medical education and research, help standardize medical practice, and enforce codes of professional conduct. The World Health Organization (WHO) is the chief international medical organization. It promotes public health programmes and the exchange of medical knowledge. WHO is especially dedicated to improving the quality of medical care in developing countries.
Most developing countries have a shortage of doctors and hospitals, especially in rural areas. Specially trained personnel assess local health problems, taking into account the environment, climate, nutrition, and prevalence of the disease. A medical care programme includes the provision of doctors, nurses, visiting clinics, and access to hospitals. Local health care assistants are trained to take on many routine tasks. Immunization campaigns, care of pregnant women, and clean water are some of the services needed to help people remain healthy.
Health for All. World Health Organization (WHO) delegates from 134 countries met at Alma-Ata, Kazakhstan, in 1978, to discuss the health of the world. Noting the unequal distribution of health care, they declared a goal of Health for All by the year 2000. This aims to achieve a level of health that will permit all people to lead socially and economically productive life. Countries as far apart as Bangladesh, Canada, Finland, Thailand, and the United Kingdom are adopting the principles of health for all.
Communities take on the responsibilities for their own health care. The Mexican Constitution now guarantees access to health care among the rights of its citizens. The role of medical research. Progress in medicine depends largely on the work of medical research. Medical researchers strive to increase our knowledge of (1) how the healthy body works; (2) how it is disturbed by disease; and (3) how disease can be prevented or cured. Some medical researchers are doctors, but others are purely research scientists. Much medical research is done in laboratories. But doctors also carry out research by observing groups of patients.
Most medical discoveries provide clues to only part of the solution of a difficult medical problem. As a result, the problem is solved only after years of work by many people. But researchers sometimes make dramatic discoveries. An outstanding example of a dramatic discovery was the development of an effective polio vaccine by the American research scientist Jonas E. Salk in the early 1950’s. For more information on medical research, see the article SCIENCE (The history of science).
Medical education. Standards and requirements of medical education are similar in almost every country around the world. Medical studies are very demanding, requiring increasing amounts of material to be learned in a limited time. In addition, students must acquire the skills needed for performing a physical examination and history-taking. After gaining bedside experience, the trainee can apply theoretical knowledge to problems.
All medical students begin their education at university. During five to seven years at the university, they progress through basic sciences (biology, chemistry, and physics), structure and function of the body (anatomy, physiology, and biochemistry), and the disease processes (pathology and microbiology). In the final clinical years, they gain experience seeing patients in hospitals and clinics.
The basic training ends with a year’s hospital residency working in different areas. These areas include general medicine and surgery, obstetrics and gynecology, and pediatrics. On graduating, newly qualified doctors are admitted to the national medical register. Further theoretical and clinical training is usually based in teaching hospitals. Academic staff and advanced facilities enable postgraduates to specialize in any area of medicine. General practitioners undertake at least three years of postgraduate training.
Colleges and associations exist which represent the major specialties. They are made up of leading members of the medical profession. These independent bodies maintain standards by administering examinations to candidates who have completed their specialist training. They promote research and act as a forum for the exchange of information and ideas among specialists from all over the world.
The specialties. Specialization in medicine has existed throughout the ages. Before the 1700s, doctors received professional education at university, whereas surgeons were craftsmen who served an apprenticeship. The distinction disappeared with the founding of hospitals, and eventually, the two professions received the same basic training. As doctors became able to treat more conditions, they focused their attention on narrower fields.
Accident and emergency medicine (A&E) deals with sudden, unexpected illness and injury. Many hospitals have an A&E department that handles both minor and serious cases, as well as psychiatric emergencies. Trauma centres concentrate on severely injured people who urgently need special attention and immediate surgery. Allergy and immunology deal with disorders of the immune system, including allergies, autoimmune diseases, and immune deficiencies.
Anesthesia is a wide-ranging specialty. Anesthetists give local and general anesthetics during surgery and maintain the patient’s condition throughout the operation. Some anesthetists concentrate on areas such as neurosurgery or obstetrics. Others run pain clinics or intensive care units in addition to their theatre duties. Cardiology covers the diagnosis and treatment of diseases of the heart and circulatory system. Cardiologists carry out medical treatment, while cardiothoracic surgeons perform operations on the heart, lungs, and major blood vessels.
Community medicine covers the health of society and the influences that act on entire populations, such as nutrition, the environment, and the provision of health care. Colon and rectal surgery is the surgical treatment of disorders of the lower digestive tract. Dermatology diagnoses and treats diseases of the skin, nails, and hair. General or family practice is the supervision of the health of family members of all ages. General practitioners offer domiciliary care and preventive medicine.
General surgery includes operations on many organs and tissues. General surgeons treat conditions such as appendicitis, cancer, and diseases of the digestive tract. Geriatrics covers the problems that occur in old age and the care of the elderly. Gynecology comprises the diagnosis and treatment of disorders of the female reproductive organs.
Internal medicine is the diagnosis and nonsurgical treatment of diseases of adults. Specialists are called internists. Some internists limit their practice to allergies; diseases of the heart and blood vessels; disorders of the digestive tract; diseases of the lungs; diseases of the joints; or disorders of the kidneys. Neurology deals with diseases of the peripheral nerves, spinal cord, and brain. Neurosurgeons provide surgical treatment for diseases that affect the nervous system.
Nuclear medicine is the use of radioactive isotopes to diagnose and treat diseases. Obstetrics includes the care of women during pregnancy and during and immediately after childbirth. Oncology is the study of tumours. Ophthalmology is the study of the eye and the diagnosis and treatment of eye diseases. Orthopedics is the branch of surgery concerned with diseases of, or damage to, bones and joints. Otolaryngology, also known as ENT, is the diagnosis and treatment of diseases of the ear, nose, and throat.
Pediatrics deals with the health care of children under the age of 15 years. A new subspeciality is a neonatology, the care of sick newborns, including premature babies. Pathology studies changes which cause disease or result from disease processes. Pathologists examine blood, body fluid, and tissue samples under the microscope. They oversee laboratory tests to determine what disease is present or how it is affecting the body. Plastic and reconstructive surgery restores parts of the body that have been damaged by accident or disease, and also changes the appearance of body parts. Maxillo-facial surgeons specialize in the head and neck.
Preventive medicine deals with the relation between the environment and health. Specialists may limit their practice to such fields as public health and aviation medicine. Psychiatry is concerned with the diagnosis, treatment, and prevention of mental disorders. Radiology is the use of X-rays in the diagnosis and treatment of disease. Rheumatologists are doctors who diagnose and treat disorders of the joints, muscles, ligaments, and tendons. Thoracic surgery is the surgical treatment of diseases of the heart, lungs, or large blood vessels in the chest. Urology deals with diseases of organs that pass urine and of the male reproductive organs.
Promoting health care. Many other people are involved in medical care, whether promoting health and preventing disability or caring for the sick and helping with their rehabilitation. Government agencies, nurses, and voluntary groups provide health education and support. Occupational therapists work with people, especially the elderly and chronically ill, who have problems returning to everyday activities. Their patients may need to relearn basic skills such as dressing and cooking, or their homes may need to be adapted because of an acquired disability.
Physiotherapists work with patients to overcome or compensate for physical disabilities. Hospital social workers, who are familiar with the medical and social situations of patients, make sure that people discharged from the hospital have access to all the necessary social services. They offer to counsel to patients and their families and can put them in touch with appropriate support groups.
Providing technical support. Many important medical careers require special technical skills. Laboratory technicians, for example, perform chemical and microscopic tests that may be needed for accurate diagnosis. Radiographers prepare patients for X-rays and other imaging techniques, such as ultrasound, computerized tomography (CT scan), and magnetic resonance imaging (MRI). These technicians also operate the imaging equipment under the supervision of a medical specialist called a radiologist.
Organizing health care is extremely complex. It includes services such as health education, medical care by general practitioners or hospitals, and long-term care in hospitals, day centres, and homes. In many industrial countries, infectious diseases are being controlled; infant mortality rates are low, and life spans are increasing. But diseases of the past are being replaced by such new ones as heart disease, stroke, and cancer. Diagnosis and treatment of these diseases depend on advanced technologies. The technologies can provide more efficient treatment of these diseases, but they are very expensive.
In many countries, the size of the elderly population is growing rapidly, increasing the demand for medical care. Many countries accept the universal goal of making adequate medical care available to all as a basic medical right. However, present methods of funding, in whatever form, cannot keep pace with the escalating costs of medical care and demand for treatment. The crisis continues to grow, and no country has yet been able to address it successfully.
In China and some other countries, medicine is completely socialized–that is, all medical facilities are publicly owned and all medical personnel are paid from public funds. Every citizen receives medical care free or at a very low cost. In some other countries, medicine is largely socialized. The United Kingdom (UK) is the best-known example. In the UK, the central government owns most medical facilities, pays most medical personnel, and provides most medical carefree or at low cost.
In many other countries, including most Western European countries, Japan, and Australia, medicine is partly socialized. The central government does not own most medical facilities, nor does it pay most doctors, who are self-employed. But these countries have a national health insurance plan that provides free medical care or refunds almost all the money a patient spends for medical care. The plan is financed through the social security system in almost all countries and is compulsory for workers covered by social security. Doctors who take part in the national plan must charge a set fee, but patients may choose their doctor and hospital.
A system of mixed medical care–private health care paid for by insurance or directly, with some state provision for the poor–is typical of countries such as the United States and India. In general, medical services are not evenly distributed, as doctors and hospitals tend to be concentrated in the cities. In some developing countries, medical treatment may be nonexistent in poor areas located in remote rural districts. Governments and international aid agencies are trying to provide a service to these rural areas, with the help of nurses, midwives, mobile clinics, improved health education, and even traditional healers.
History. In prehistoric times, people believed that angry gods or evil spirits caused disease. To cure the sick, the gods had to be pacified or the evil spirits are driven from the body. In time, this task became the job of the first shamans (tribal priests who tried to pacify the gods or drive out the evil spirits). The first known surgical treatment was an operation called trephining. Trephining involved the use of a stone instrument to cut a hole in a patient’s skull.
Scientists have found fossils of such skulls that date as far back as 10,000 years. Early people may have performed the operations to release spirits believed responsible for headaches, mental illness, or epilepsy. However, trephining could have brought relief in some cases. Surgeons still practise trephining to relieve certain types of pressure on the brain. Prehistoric people probably also discovered that many plants can be used as drugs. For example, the use of willow bark to relieve pain probably dates back thousands of years.
Today, scientists know that willow bark contains salicin, a substance related to the salicylates used in making aspirin. Origins in the Middle East. By about 3000 B.C., the Egyptians, who had developed one of the world’s first great civilizations, began making important medical progress. The world’s first physician (doctor) known by name was the Egyptian Imhotep, who lived about 2650 B.C. The Egyptians later worshipped him as the god of healing (see IMHOTEP). About 2500 B.C., Egyptian physicians began to specialize. Some physicians treated only diseases of the eyes or teeth. Others specialized in internal diseases.
Egyptian surgeons produced a textbook that told how to treat dislocated or fractured bones and external abscesses, tumours, ulcers, and wounds. Other ancient Middle Eastern civilizations also contributed to medical progress. The ancient Israelites, for example, made progress in preventive medicine from about 1200 to 600 B.C. The Israelites required strict isolation of people with gonorrhea, leprosy, and other contagious diseases. They also prohibited the contamination of public wells and the eating of pork and other foods that might carry disease.
China and India. The ancient Chinese developed medical practices that have been handed down almost unchanged to the present day. This traditional medicine is based on the belief that two life forces, yin and yang, flow through the human body. Disease results when the two forces become out of balance. To restore the balance, the Chinese developed the practice of acupuncture–inserting needles into parts of the body thought to control the flow of yin and yang. Chinese doctors still practise acupuncture.
The technique has gained some popularity in Western countries, where it is occasionally used to treat certain pain disorders. But many Western doctors question its value. See ACUPUNCTURE. In ancient India, one system of medical practice became known as Ayurveda. It stressed the prevention as well as the treatment of illness. By 600 to 500 B.C., practitioners of Ayurveda had developed an impressive knowledge of drugs and surgery. Indian surgeons successfully performed many kinds of operations, including amputations and plastic surgery.
Greece and Rome. The civilization of ancient Greece was at its peak during the 400’s B.C. Throughout this period, sick people flocked to temples dedicated to the Greek god of healing, Asclepius, seeking magical cures. But at the same time, the great Greek physician Hippocrates began showing that disease has only natural causes. He thus became the first physician known to consider medicine a science and art separate from the practice of religion. The Hippocratic oath, an expression of early medical ethics, reflects Hippocrates’ high ideals. But the oath was probably composed of a number of sources rather than by Hippocrates himself. Modern medical ethics are based on the Hippocratic oath. For the text of the oath, see the article HIPPOCRATES.
After 300 B.C., the city of Rome gradually conquered much of the civilized world, including Egypt and Greece. The Romans got most of their medical knowledge from Egypt and Greece. Their own medical achievements were largely in public health. The Romans built aqueducts that carried more than 1 billion litres of freshwater to Rome each day. They also built an excellent sewage system in Rome. The Greek physician Galen, who practised medicine in Rome during the A.D. 100’s, made the most important contributions to medicine in Roman times. Galen performed experiments on animals and used his findings to develop the first medical theories based on scientific experiments.
For this reason, he is considered the founder of experimental medicine. But because his knowledge of anatomy was based largely on animal experiments, Galen developed many false notions about how the human body works. Galen wrote numerous books describing his medical theories. These theories, many of which were wrong, guided doctors for hundreds of years. The Middle Ages. During the Middle Ages, which lasted from the A.D. 400’s to the 1500s, the Islamic empires of Southwest and Central Asia and Spain contributed greatly to medicine. Rhazes, a Persian-born physician of the late 800’s and early 900’s, wrote the first accurate descriptions of measles and smallpox.
Avicenna, an Arab physician of the late 900’s and early 1000’s, produced a vast medical encyclopedia called Canon of Medicine. It summed up the medical knowledge of the time and accurately described meningitis, tetanus, and many other diseases. The work became popular in Europe, where it influenced medical education for more than 600 years. A series of epidemics swept across Europe during the Middle Ages. Outbreaks of leprosy began in the 500’s and reached their peak in the 1200s. In the mid-1300s, a terrible outbreak of plague, now known as the Black Death, killed about one-third of Europe’s people. Throughout the medieval period, smallpox and other diseases attacked hundreds of thousands of people.
The chief medical advances in Europe during the Middle Ages were the founding of many hospitals and the first university medical schools. Christian religious groups established hundreds of charitable hospitals for victims of leprosy. In the 900’s, a medical school was started in Salerno, Italy. It became the chief centre of medical learning in Europe during the 1000’s and 1100s. Other important medical schools developed in Europe after 1000. During the 1100s and 1200s, many of these schools became part of newly developing universities, such as the University of Bologna in Italy and the University of Paris in France.
The Renaissance. A new scientific spirit developed during the Renaissance, the great cultural movement that swept across Western Europe from about 1300 to the 1600s. Before this time, most societies had strictly limited the practice of dissecting (cutting up) human corpses for scientific study. But laws against dissection were relaxed during the Renaissance. As a result, the first truly scientific studies of the human body became possible.
During the late 1400’s and early 1500s, the Italian artist Leonardo da Vinci performed many dissections to learn more about human anatomy. He recorded his findings in a series of more than 750 drawings. Andreas Vesalius, a doctor and professor of medicine at the University of Padua in Italy, also performed numerous dissections. Vesalius used his findings to write the first scientific textbook on human anatomy, a work called On the Structure of the Human Body (1543). This book gradually replaced the texts of Galen and Avicenna.
Other doctors also made outstanding contributions to medical science in the 1500s. A French army surgeon named Ambroise Pare improved surgical techniques to such an extent that he is considered the father of modern surgery. For example, he opposed the common practice of cauterizing (burning) wounds with boiling oil to prevent infection. Instead, he developed the much less traumatic method of applying a mild ointment and then allowing the wound to heal naturally. Philippus Paracelsus, a Swiss doctor, stressed the importance of chemistry in the preparation of drugs. He pointed out that in many drugs consisting of several ingredients, one ingredient made another useless.
The beginnings of modern research. The English doctor William Harvey performed many experiments in the early 1600s to learn how blood circulates through the body. Before Harvey, scientists had studied only parts of the process and invented theories to fill in the gaps. Harvey studied the entire problem. He performed dissections on both human beings and animals and made careful studies of the human pulse and heartbeat. Harvey concluded that the heart acts as a pump, forcing blood through the arteries to all parts of the body. He also showed that the blood returns to the heart through the veins.
Harvey described his findings in An Anatomical Study of the Motion of the Heart and of the Blood in Animals (1628). His discovery of how blood circulates marked a turning point in medical history. After Harvey, scientists realized that knowledge of how the body works depends on knowledge of the body’s structure. In the mid-1600s, a Dutch amateur scientist named Anton van Leeuwenhoek began using a microscope to study organisms invisible to the naked eye. Today, such organisms are called microorganisms or microbes. In the mid-1670s, Leeuwenhoek discovered certain microbes that later became known as bacteria.
Leeuwenhoek did not understand the role of microbes in nature. But his research paved the way for the eventual discovery that certain microbes cause disease. The development of immunology. Smallpox was one of the most feared and highly contagious diseases of the 1700s. It killed many people every year and scarred others for life. Doctors had known for hundreds of years that a person who recovered from smallpox developed lifelong immunity (resistance) to it. To provide this immunity, doctors sometimes inoculated people with matter from a smallpox sore, hoping they would develop only a mild case of the disease. But such inoculations were dangerous. Some people developed a severe case of smallpox instead of a mild one. Other inoculated people spread the disease.
In 1796, an English doctor named Edward Jenner discovered a safe method of making people immune to smallpox. He inoculated a young boy with matter from a cowpox sore. The boy developed cowpox, a relatively harmless disease related to smallpox. But when Jenner later injected the boy with matter from a smallpox sore, the boy did not come down with the disease. His cowpox had helped his body build up an immunity to smallpox. Jenner’s classic experiment was the first officially recorded vaccination. The experiment was the first successful therapy to alter the body’s immune system.
Discovery of the first anesthetic. For thousands of years, doctors tried to dull pain during surgery by administering alcoholic drinks, opium, and various other drugs. But no drug had proved really effective in reducing pain until the discovery of ether and chloroform in the 1840s. With an effective anesthetic, doctors could perform operations never possible before. The scientific study of disease, called pathology, developed during the 1800s. Rudolf Virchow, a German doctor and scientist, led the development. Virchow believed that the only way to understand the nature of the disease was by close examination of the affected body cells.
He did important research into such diseases as leukemia and tuberculosis. The development of many improved microscopes in the early 1800s made his studies possible. Nursing began to improve in the late 1800s after the example set by Florence Nightingale during the Crimean War (1853-1856), and the training she established at St Thomas’s Hospital in London. Scientists of the 1800s made dramatic progress in learning the causes of infectious diseases. As early as the 1500s, scholars had suggested that tiny, invisible “seeds” caused some diseases. The bacteria discovered by Leeuwenhoek in the 1600s fitted this description. In the late 1800s, the research of Louis Pasteur and Robert Koch firmly established the germ theory of disease.
Pasteur, a brilliant French chemist, proved that microbes are living organisms and that certain kinds of microbes cause disease. He also proved that killing specific microbes stops the spread of specific diseases. Koch, a German doctor, invented a method for determining which bacteria cause particular diseases. This method enabled him to identify the bacterium that causes anthrax, a severe disease of people and livestock. The anthrax bacillus thus became the first microbe definitely linked to a particular disease. Other research scientists followed the lead of these two pioneers. By the end of the 1800s, researchers had discovered the kinds of bacteria and other microbes responsible for such infectious diseases as bubonic plague, cholera, diphtheria, dysentery, gonorrhea, leprosy, malaria, pneumonia, tetanus, and tuberculosis.
Introduction of antiseptic surgery. Hospitals paid little attention to cleanliness before the mid-1800s. Operating theatres were often dirty, and surgeons operated in street clothes. Up to half of all surgical patients died of infections. In 1847, a Hungarian doctor, Ignaz Semmelweis, stressed the need for cleanliness. But Semmelweis knew little about the germ theory of disease. Pasteur’s early work on bacteria convinced an English surgeon named Joseph Lister that germs caused many of the deaths of surgical patients.
In 1865, Lister began using carbolic acid, a powerful disinfectant, to sterilize surgical wounds. But this method was later replaced by a more efficient technique known as aseptic surgery. This technique involved keeping germs away from surgical wounds in the first place instead of trying to kill germs already there. Surgeons began to wash thoroughly before an operation and to wear surgical gowns, gloves, and masks. The medical revolution. Advances in science led to a revolution in the diagnosis and treatment of diseases during the 1900s. For example, the discovery of X-rays by the German physicist Wilhelm Roentgen in 1895 enabled doctors to “see” inside the human body to diagnose illnesses and injuries.
The discovery of radium by the French physicists Pierre and Marie Curie in 1898 provided a powerful weapon against cancer. In the early 1900s, Christiaan Eijkman of the Netherlands, Frederick Hopkins of England, and a number of other medical scientists showed the importance of vitamins. Their achievements helped conquer such nutritional diseases as beriberi, rickets, and scurvy. In about 1910, the German bacteriologist Paul Ehrlich introduced a new method of attacking infectious diseases. Ehrlich’s method, called chemotherapy, consisted of finding chemicals that would kill bacteria in the body without harming the patient. The first chemical produced was salvarsan, an arsenic compound used to treat syphilis.
Ehrlich’s work greatly advanced drug research. In 1935, a German doctor, Gerhard Domagk, discovered the ability of sulpha drugs to cure infections in animals. His discovery led to the development of sulpha drugs to treat diseases in human beings. In 1928, the British bacteriologist, Alexander Fleming, extracted penicillin from a blue mould. The Australian pathologist Howard Florey, and the German-born biochemist Ernst Chain, worked together to develop penicillin into an injectable form. Soon other antibiotics became available, including chloramphenicol in 1947, the first broad-spectrum antibiotic (a medicine that fights several diseases at once).
Researchers also study the way diseases act upon the body. Pathologists now call upon many technologies to identify disease processes. One of the most sensitive, radioimmunoassay (RIA), was developed in the United States by Solomon Berson and Rosalyn Yalow in 1959. RIA tags substances in the blood with a radioactive label so that even minute quantities can be detected and measured. In the 1980s, scientists developed a number of antiviral agents. Acyclovir fights herpes simplex and shingles. Zidovudine is used against Acquired Immune Deficiency Syndrome (AIDS). These new drugs prevent the viruses from replicating themselves.
Genetic engineering, developed during the 1970s, helped in the treatment of hormonal disorders. Insulin, used in treating diabetics, used to be obtained from the pancreas of cattle and pigs. However, many people were allergic to insulin from animals. Since 1982, insulin has been produced using genetic engineering. The genetically engineered insulin resembles that of humans and does not cause an allergic reaction. In 1985, the second genetically engineered drug, human growth hormone, became available. The growth hormone helps children deficient in this hormone grow to normal height.
Heart surgery techniques improved after 1953 when American surgeon John Gibbon introduced the heart-lung machine. This machine takes over the functions of the heart and lung while the heart is being operated upon. In 1967, the American heart surgeon, Rene Favaloro, performed the first coronary bypass operation (replacing blocked arteries with healthy grafts). Transplants. Animal experiments in the early 1900s showed that transplanted organs could survive and work. In 1905, the French-American surgeon, Alexis Carrel, developed a technique for joining blood vessels to restore circulation. A Paris surgeon performed the first kidney graft in 1953. It failed after 21 days because the patient’s immune system rejected the implanted organ.
Christiaan Barnard performed the first heart transplant in South Africa in 1967. The patient, Louis Washansky, died of a lung infection 28 days after the operation. In the United States, Thomas Starzl and F. D. Moore implanted livers in 1963. In the same year, J. D. Hardy performed a lung graft. Research has been carried out into methods of preventing organ rejection, and methods of preserving donor organs in a viable condition until they can be implanted. The new antirejection drug, cyclosporin, was discovered in 1978.
In 1900, the Austrian-American medical scientist Karl Landsteiner discovered blood groups and realized that donor and recipient had to be matched. The storage and transportation of donated blood became possible in 1914 when researchers found that sodium citrate could be added to prevent clotting.
Landsteiner discovered the Rhesus (Rh) factor in 1940. Before then, the immune system of Rh-negative mothers destroyed the blood of their Rh-positive babies. Complete exchange transfusions carried out immediately after birth saved many newborns. Transfusions were given in the womb–a technique pioneered in New Zealand in 1963–improved survival chances. Other technological advances. Computerized tomography (CT), developed in the United Kingdom in 1972, feeds X-ray pictures of the body into a computer and obtains detailed cross-sectional images.
Digital subtraction angiography (DSA) takes pictures of blood vessels before and after the radiopaque dye is injected into the bloodstream. The computer “subtracts” the second series from the first, and the difference between the two provides a clear outline of the circulation. A Scottish obstetrician, Ian Donald, pioneered the use of ultrasound (high-frequency sound waves) in 1958. Ultrasound observes a fetus inside the womb, without risk to the child or mother. Echocardiography enables cardiologists to study the heart in motion, and even the blood flow through damaged heart valves.
Magnetic resonance imaging (MRI), invented in the UK in 1973, is based on the behaviour of atoms. The patient is positioned inside a powerful magnet. Radio impulses cause the nuclei of the atoms in the patient’s body to give off a signal. Each type of tissue gives off a signal which is converted by the computer into a remarkably clear picture. MRI allows neurologists to observe diseases of the nervous system in detail.
The practice of medicine has come a long way from the days when doctors were powerless in the face of disease and suffering. But, while research has yielded many effective treatments, it has also shown that the prevention of many contemporary ailments lies in people’s own hands. Scientists have demonstrated how emotional stress and diet contribute to heart disease. In the 1920s, researchers first suggested an association between smoking and cancer. The contribution of environmental factors to cancer was shown by Sir Percival Potts in 1775. He suggested that soot caused cancer of the scrotum and nasal cavity in chimney sweeps.
Modern medicine is also concerned to eliminate the causes of premature death and unnecessary suffering. Doctors–and patients–are beginning to see that health does not depend solely on expensive drugs and therapies. Other factors increasingly taken into account are the patients’ environment and way of life, and the attitude of the patient towards preventing health problems. Legal and ethical questions. Medical progress has raised a large number of new, complex, and difficult problems in the day-to-day practice of medicine. For example, modern medicine’s ability to prolong life raises the question of when death actually occurs.
In the past, people were considered legally dead when their hearts and breathing stopped. But today, machines can keep a patient’s heart and lungs working for days or even months after they can no longer function by themselves. As a result, many experts believe that a person should be considered legally dead when the brain stops functioning. Other ethical questions raised by modern medicine concern organ transplants, abortion, euthanasia (helping or allowing patients to die), gene therapy, and the use of human subjects in medical experiments. Some hospitals have established ethics committees that doctors can consult when faced with an especially difficult ethical question.
Malpractice is a growing legal dilemma confronting doctors today. Doctors may be accused of malpractice if a patient believes that he or she has been injured through the doctor’s mistake or negligence. Some doctors believe that malpractice suits have become more common because many patients now have unrealistic expectations about medical care. Patients expect their treatment to be successful, even though some modern medical techniques are highly complicated and potentially dangerous.
Problems for research. Medical research has yet to find the underlying causes of diseases of the heart and blood vessels and of cancer–the chief causes of death in the industrial world. Knowledge of the molecular and cellular causes of these disorders will help scientists develop better ways of treating and preventing them. Women’s health issues, especially breast cancer, hip fracture, and mother-and-child care, are also receiving attention from researchers. In addition, many researchers are studying how preventive strategies, such as exercising, eating a balanced diet, and avoiding alcohol and cigarettes, can be made part of daily routines. Such strategies can reduce death rates, especially among middle-aged and younger adults.