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Effects of the Black Death
The Black Death, an epidemic of plague in Europe that lasted from 1347 to 1351, resulted in the deaths of almost one-quarter of Europe’s population. The Black Death was the first in a cycle of plagues in Europe that continued into the 18th century. Shown here, the French city of Marseille is devastated by a later outbreak of plague.
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In early medieval Europe, religious groups established hospitals and infirmaries in monasteries and later developed charitable institutions designed to care for the victims of vast epidemics of bubonic plague, leprosy, smallpox, and other diseases that swept Europe during the Middle Ages. The Benedictines were especially active in this work, collecting and studying ancient medical texts in their library at Monte Cassino near Salerno, Italy. St. Benedict of Nursia, the founder of the order, obligated its members to study the sciences, especially medicine. The abbot of Monte Cassino, Bertharius, was himself a famous physician.
During the 9th and 10th centuries Salerno became Europe’s center for medical care and education and was the site of the first Western school of medicine. By the 12th century other medical schools were established at the universities of Bologna and Padua in Italy, the University of Paris in France, and Oxford University in England.
In the 13th century, medical licensure by examination was endorsed and strict measures were instituted for the control of public hygiene. Representative scientists of this period include the German scholastic St. Albertus Magnus, who engaged in biological research, and the English philosopher Roger Bacon, who undertook research in optics and refraction and was the first scholar to suggest that medicine should rely on remedies provided by chemistry. Bacon, often regarded as an original thinker and pioneer in experimental science, was strongly influenced by the authority of Greek and Arabic medicine.
The period of the Renaissance, which began at the end of the 14th century and lasted for about 200 years, was one of the most revolutionary and stimulating in the history of mankind. Invention of printing and gunpowder, discovery of America, the new cosmology of Copernicus, the Reformation, the great voyages of discovery—all these new forces were working to free science and medicine from the shackles of medieval stagnation. The fall of Constantinople in 1453 scattered the Greek scholars, with their precious manuscripts, all over Europe.
The revival of learning in Western civilizations brought great advances in human anatomy. Some resulted from the work of artists, including Italian Leonardo da Vinci, who dissected human corpses to portray muscles and other structures more accurately. Andreas Vesalius, a Belgian anatomist, clearly demonstrated hundreds of anatomical errors introduced by Galen centuries earlier. Gabriel Falliopius discovered the uterine tubes named after him (see Fallopian Tube) and diagnosed ear diseases with an ear speculum. He described in detail the muscles of the eye, tear ducts, and fallopian tubes. Italian physician Girolamo Fracastoro recognized that infectious diseases are spread by invisible so-called seeds that can reproduce themselves. He founded modern epidemiology, the study of how diseases spread. The term syphilis, applied to the virulent disease then devastating Europe, was derived from his famous poem, “Syphilis sive Morbus Gallicus” (Syphilis or Disease of Gauls, 1530). Ambroise Paré introduced new surgical techniques and helped to found modern surgery.
The event that dominated 17th-century medicine and marked the beginning of a new epoch in medical science was the discovery of how the blood circulates in the body by the English physician and anatomist William Harvey. Harvey's “Essay on the Motion of the Heart and the Blood” (1628) established that the heart pumps the blood in continuous circulation. The Italian anatomist Marcello Malpighi advanced Harvey's work by his discovery of tiny blood vessels called capillaries, and the Italian anatomist Gasparo Aselli provided the first description of the lacteals, capillaries found in the lymphatic system. In England the physician Thomas Willis investigated the anatomy of the brain and the nervous system and was the first to describe diabetes mellitus. The English physician Francis Glisson advanced the knowledge of the anatomy of the liver, described the nutritional disorder rickets (sometimes called Glisson's disease), and was the first to prove that muscles contract when activity is performed. The English physician Richard Lower studied the anatomy of the heart, showed how blood interacts with air, and performed one of the first blood transfusions.
The French mathematician and philosopher René Descartes, who also made anatomical dissections and investigated the anatomy of the eye and the mechanism of vision, maintained that the body functioned as a machine. This view was adopted by the so-called iatrophysicists, such as Italian physician Sanctorius, who investigated metabolism, and the Italian mathematician and physicist Giovanni Alfonso Borelli, who worked in the area of physiology. Opponents of this view were the iatrochemists, who regarded life as a series of chemical processes, including Jan Baptista van Helmont, a Flemish physician and chemist, and Prussian anatomist Franciscus Sylvius, who studied the chemistry of digestion and emphasized the treatment of disease by drugs.
The English physician Thomas Sydenham, called the English Hippocrates, and later the Dutch physician Hermann Boerhaave, reestablished the significance of bedside instruction in their emphasis on the clinical approach to medicine. Sydenham carried out extensive studies on malaria and introduced the new treatment quinine, obtained from cinchona bark, into Europe in 1632. After the invention of the first compound microscope in 1590, Dutch scientist Antoni van Leeuwenhoek used this groundbreaking technology in 1676 to identify organisms later called bacteria. This was the first step toward recognition that microbes were the cause of infectious disease.
Vaccination with Cowpox
A cartoon satirizes British physician Edward Jenner, who is shown injecting patients with cowpox virus, resulting in their transformation into cows. Jenner lived from 1749 to 1823. His discovery that cowpox was an effective vaccine against smallpox was initially greeted with skepticism, but soon accepted. The procedure dramatically reduced the incidence of smallpox, once a major cause of death in the 18th century.
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The 18th century continued to be marked by unsupported theories. The German physician and chemist Georg Ernst Stahl believed that the soul is the vital principle and that it controls organic development; in contrast, the German physician Friedrich Hoffmann considered the body a machine and life a mechanical process. These opposing theories of the vitalists and the mechanists were influential in 18th-century medicine. The British physician William Cullen attributed disease to the excess or deficiency of nervous energy; and the physician John Brown of Edinburgh taught that disease was caused by weakness or inadequate stimulation of the organism. According to his theories, known as the Brunonian system, stimulation should be increased by treatment with irritants and large dosages of drugs. In opposition to this system, the German physician Samuel Hahnemann developed the system of homeopathy late in the 18th century, which emphasized small dosages of drugs to cure disease.
Other unusual medical practices developed toward the end of the 18th century include phrenology, a theory formulated by the German physician Franz Joseph Gall, who believed that examination of the skull of an individual would reveal information about mental functions. The theory of animal magnetism developed by the Austrian physician Franz Mesmer was based on the existence of a magnetic force having a powerful influence on the human body.
Despite these unorthodox medical practices, the end of the 18th century was marked by many true medical innovations. British physicians William Smellie and William Hunter made advances in obstetrics that established this field as a separate branch of medicine. The British social reformer John Howard furthered humane treatment for hospital patients and prison inmates throughout Europe. In 1796 British physician Edward Jenner introduced vaccination to prevent smallpox. His efforts both controlled this dreaded disease and also established the science of immunization.
Used to listen to sounds arising especially from the heart and lungs, a stethoscope has a two-part sound-detecting device at one end. The bell, bowl-shaped with a hole in the center, detects low-pitched sounds when the rim is pressed against the skin. The other side, called the diaphragm, has a thin, flat plastic cover. The diaphragm detects high-pitched sounds. A doctor hears these sounds through the earpieces of the stethoscope as they pass up the Y-shaped rubber tubing.
Herbert Wagner/Phototake NYC
Many discoveries made in the 19th century led to great advances in diagnosis and treatment of disease and in surgical methods. Medicine’s single most important diagnostic tool, the stethoscope, an instrument used to detect sounds in the body such as a heart beat, was invented in 1819 by French physician René-Théophile-Hyacinthe Laënnec. A number of brilliant British clinicians studied and described diseases that today bear their names. British physician Thomas Addison discovered the disorder of the adrenal glands now known as Addison's disease; Richard Bright diagnosed the kidney disorder, Bright's disease; British physician Thomas Hodgkin described a cancer of lymphatic tissue now known as Hodgkin's disease; British surgeon and paleontologist James Parkinson described the chronic nervous system disease called Parkinson disease; and the Irish physician Robert James Graves diagnosed the thyroid disorder exophthalmic goiter, sometimes called Graves' disease.
Medicine, like all other sciences, is subject to influences from other fields of study. This was particularly true during the 19th century, renowned for its great scientific innovations. For instance, the evolutionary theory proposed by Charles Darwin in On the Origin of Species by Means of Natural Selection (1859) revived interest in the science of comparative anatomy and physiology. And the plant-breeding experiments of the Austrian biologist Gregor Johann Mendel in 1866, although initially overlooked, eventually had a similar effect in stimulating studies in human genetics (see Heredity).
Since its accidental discovery in 1895, the X ray has been an important diagnostic and therapeutic tool. Produced by bombarding a target made of tungsten with high-speed electrons, X rays are absorbed by various tissues of the body in a predictable manner. They are absorbed by dense bone and pass through the soft tissue of internal organs. On a photographic plate, bone appears white and soft tissues appear gray. While diagnostic dental and medical X rays are low-intensity beams, high-intensity X rays, capable of destroying tissue, are used in the treatment of tumors. Rapidly dividing cancerous cells are especially vulnerable to X rays.
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German pathologist Rudolf Virchow pioneered development of pathology, the scientific study of disease. Virchow showed that all diseases result from disorders in cells, the basic units of body tissue. His doctrine that the cell is the seat of disease remains the cornerstone of modern medical science. In France, physiologist Claude Bernard performed important research on the pancreas, liver, and nervous system. His scientific studies, which emphasized that an experiment should be objective and prove or disprove a hypothesis, were the basis for the scientific method used today. Bernard's work on the interaction of the digestive system and the vasomotor system, which controls the size of blood vessels, was developed further by the Russian physiologist Ivan Petrovich Pavlov, who developed the theory of the conditioned reflex, the basis of human behaviorism.
A milestone in medical history occurred in the 1870s when French chemist Louis Pasteur and German physician Robert Koch separately established the germ theory of disease. Important in the development of this theory was the pioneering work of the American physician and author Oliver Wendell Holmes and of the Hungarian obstetrician Ignaz Philipp Semmelweis, who showed that the high rate of mortality in women after childbirth was attributable to infectious agents transmitted by unwashed hands (see Puerperal Fever).
Carbolic Steam Spray
The carbolic steam spray device invented by Joseph Lister in 1865 is credited with lowering the surgical mortality rate of the 1860s from 50 percent to approximately 12 percent. Drawing on the theories and discoveries of Louis Pasteur, Lister developed his own techniques of applying carbolic acid directly to wounds and surgical instruments, which led to the modern practice of antiseptic medicine.
Soon after the germ theory was recognized, the causes of such age-old scourges as anthrax, diphtheria, tuberculosis, leprosy, and plague were isolated. Pasteur developed a way to prevent rabies using a vaccine in 1885. In the last decade of the 19th century, German physician Emil von Behring and German bacteriologist Paul Ehrlich developed techniques for immunizing against diphtheria and tetanus.
New understanding of infectious diseases made surgery safer. Until the 1800s, surgeons operated in their street clothes, often without even washing their hands. Operating rooms, like other parts of hospitals, were filthy. About half of all surgery patients who survived the actual surgery typically died of infections that developed after the operation. The era of aseptic surgery, in which physicians used sterilized instruments and techniques to avoid infecting patients, was heralded by British surgeon and biologist Joseph Lister. With his introduction of an effective antiseptic, carbolic acid, Lister was able to successfully reduce mortality from wound infection (see Antiseptics). Rubber gloves were first worn during surgery in 1890, and gauze masks in 1896.
A color illustration depicts German scientist Robert Koch at work in his laboratory. Considered the founder of modern medical bacteriology, Koch isolated the bacillus that causes tuberculosis in 1882. He won the Nobel Prize for physiology or medicine in 1905.
THE BETTMANN ARCHIVE/Corbis
Another great advance in surgery came with the discovery of anesthesia. Until the 19th century, doctors used alcohol, opium, and other drugs to relieve pain during surgery. These medications could sometimes dull pain but could never completely mask it—patients often suffered from shock and died during surgery. In the United States, physician Crawford Long discovered the anesthetic effects of ether in 1842, and the dentist William Morton used ether in a tooth extraction in 1846. Ether and other anesthetics reduced surgical mortality and enabled surgeons to perform longer, more complicated operations.
A new tool for diagnosing internal diseases became available in 1895 when German scientist Wilhelm Roentgen discovered X rays. The Danish physician Niels Ryberg Finsen developed an ultraviolet-ray lamp, which led to an improved prognosis for some skin diseases (see Ultraviolet Radiation). In 1898 in France, Marie and Pierre Curie discovered radium, which was later used to treat cancer.
In 1898 British physician Ronald Ross proved the role of the mosquito as a carrier of the malarial parasite, a disease that has been widespread and sometimes fatal for most of human history. In 1900 United States Army physician Walter Reed and his colleagues, acting on a suggestion made by the Cuban biologist Carlos Juan Finlay, demonstrated that the mosquito is the carrier of yellow fever. This finding lead to better sanitation and mosquito control, resulting in the virtual elimination of this disease from Cuba and other areas.
Medicine's most revolutionary advances have occurred since 1900. By the end of the 20th century, medical advances helped to increase the average person's life expectancy by almost 30 years. As people lived longer, new medical challenges emerged. Heart disease, cancer, stroke, and other conditions often associated with aging replaced infectious diseases as the leading causes of death. Physicians began to devote greater attention to preventing disease and keeping patients healthy into advanced age. Biomedical research also shifted focus to the most basic causes of diseases, including defects in individual genes.
Discovery of Penicillin
British bacteriologist Alexander Fleming discovered penicillin in 1928. Penicillin, an important antibiotic derived from mold, is effective against a wide range of disease-causing bacteria. It acts by killing bacteria directly or inhibiting their growth.
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Infectious diseases that historically have killed millions of people each year were conquered early in the 20th century by improved sanitation, antibiotics, and vaccines.
German physician Paul Ehrlich showed around 1910 that a chemical compound, arsphenamine, could treat syphilis. He opened the era of chemotherapy, in which physicians use chemical compounds that act selectively to target specific diseases.
In the early 1930s, German and French scientists showed that sulfonamide was effective in treating streptococcal bacteria infections. This discovery led to the first family of so-called wonder drugs, the sulfonamide antibiotics. In 1938 British biochemists Howard Florey and Ernst Chain purified penicillin, the bacteria-destroying compound that Alexander Fleming observed in mold ten years earlier. Streptomycin, the first antibiotic for tuberculosis, was discovered in 1944 by American microbiologist Selman Waksman. Dozens of other antibiotics were subsequently discovered, each stronger and more effective against a broader range of bacteria.
Scientists learned more about how the body's immune system protects itself from infections, resulting in new tests for diagnosing infectious diseases and new vaccines to prevent them. The Wasserman blood test for syphilis was developed in 1906 and the tuberculin skin test for tuberculosis appeared in 1908. By the 1930s new techniques for growing viruses in the laboratory led to vaccines against viral diseases. These included a yellow fever vaccine in the late 1930s and the first effective influenza vaccine in the 1940s. The American physician Jonas E. Salk developed a polio vaccine in 1954. Later virologist Albert B. Sabin developed a safer oral polio vaccine, which was in wide use by the 1960s. Later came vaccines for other childhood diseases, including measles, German measles, mumps, and chicken pox.
Infectious diseases, once thought conquered by antibiotics, became a major concern again in the 1990s. New forms of tuberculosis and other diseases resistant to antibiotics spread. Concerns also arose over new or newly recognized microbes, such as human immunodeficiency virus (HIV), the cause of acquired immunodeficiency syndrome (AIDS), which became epidemic in 1981. As human populations grow and expand into wilderness areas, humans and animals come in closer contact. A number of diseases transmitted from animals have become problematic in recent years, including the hemorrhagic fevers caused by the Ebola and Marburg viruses, hantavirus pulmonary syndrome, and Lyme disease. In other areas, physicians recognized that an easily curable bacterial infection caused most peptic ulcers, a disease once blamed on stress and diet.
Polish-born American biochemist Casimir Funk introduced the term vitamine in 1912. Researchers later identified vitamins needed by the body to prevent deficiency diseases such as beriberi, rickets, scurvy, and pellagra. As better nutrition was developed and the quality of life improved, these diseases almost disappeared from industrialized countries (see Human Nutrition). But by the end of the 20th century, other nutritional disorders emerged. Studies conducted in the United States in the 1990s showed that more than 97 million Americans were overweight and risked health problems, such as heart disease and diabetes mellitus, commonly associated with obesity.
An endoscope provides a surgeon with an illuminated and magnified view of internal organs and body cavities without making sizable incisions. Endoscopes are easily maneuverable to reach inaccessible areas and they can be equipped with a variety of instruments, from knives to lasers.
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Modern Surgery Using an Operating Microscope
The use of operating microscopes for surgical procedures has greatly assisted surgeons with seemingly impossible types of surgery such as limb reattachment and eye and ear surgery. Operating microscopes are especially useful when individual nerve fibers and blood vessels must be realigned for attachment or repair.
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Operations that people once regarded as impossible became routine in the 20th century. Many of these surgical advances resulted from improved drugs or medical technology. Better drugs to prevent rejection of transplanted organs made transplantation of hearts, kidneys, livers, lungs, and other organs removed from donors possible. Patients were kept alive with artificial kidneys and temporary artificial hearts while awaiting a transplant (see Medical Transplantation). The heart-lung machine made it possible to stop and restart the heart during coronary bypass surgery. Small fiber-optic instruments called endoscopes led to the new field of minimally invasive surgery. These new tools made it possible to remove a diseased gallbladder or appendix, for example, through small slits rather than large incisions, greatly reducing the amount of anesthesia required during the surgery and lessening recovery time. Transfusions of blood, plasma, and other saline solutions, which went into use in the 1930s, helped prevent deaths from shock in surgery patients. In the 1990s, physicians even began performing surgery to repair defects in unborn infants.
Computerized Axial Tomography (CAT) Scan
A computerized axial tomography (CAT) scan produces a cross-sectional image of a part of the body by directing a narrow X-ray beam through the body. A CAT scan is a very accurate, painless, diagnostic tool allowing examination of the interior of the body without invasive procedures.
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New methods for viewing diseased structures inside the body improved diagnosis of disease beginning in the 1970s (see Radiology). A gamma camera detects radioactive medication that attaches to certain forms of cancer cells. Computed tomography (CT) scanners use X rays to produce lifelike three-dimensional images of body structures. Magnetic resonance imaging (MRI) scanners produce highly detailed images without X rays. Positron emission tomography (PET) detects very early warning signs of disease. Sonograms, or ultrasound, taken with high-frequency sound waves diagnose disease and monitor the progress of pregnancies. X rays and high-energy particles emitted by linear accelerators also are used to treat cancer. Lithotripsy uses high-frequency sound waves to destroy some kidney stones and gallstones, conditions that once required surgery.
Brain Activity in Bipolar Disorder
These positron emission tomography scans of the brain of a person with bipolar disorder show the individual shifting from depression, top row, to mania, middle row, and back to depression, bottom row, over the course of 10 days. Blue and green indicate low levels of brain activity, while red, orange, and yellow indicate high levels of brain activity.
Dr. Michael Phelps/Lewis Baxton/UCLA School of Medicine
Even in the early part of the 20th century, mental illness was almost a sentence of doom, and mentally ill persons were handled with cruel confinement and little medical aid. In the latter half of the century, successful therapy for some mental illnesses has greatly improved the prognosis for these diseases and has partly removed their stigma.
The theories advanced by Austrian physician Sigmund Freud were among the first attempts to understand malfunctioning of the mind, but the methods of psychoanalysis advocated by Freud and modified by his followers proved ineffective for treating certain serious mental illnesses. Two early attempts to treat psychotic illness were the destruction of parts of the brain in a procedure called lobotomy, introduced in 1935, and electroconvulsive therapy, devised in 1938. Lobotomy and less severe forms of psychosurgery are now used only rarely, and electroconvulsive therapy is primarily a treatment for depressive illness that has not responded to drug therapy.
A new era in treatment of schizophrenia, a severe form of mental illness, began in the early 1950s with the introduction of phenothiazine drugs. These drugs led to a new trend, deinstitutionalization, in which patients were released from mental hospitals and treated in the community. Valium (see Diazepam) and other benzodiazepine drugs went into wide use in the 1970s for treating anxiety and other emotional illness. Late in the century, there was growing awareness about the importance of diagnosing and treating clinical depression, a leading cause of suicide. Advanced imaging techniques that show the structural and functional differences in the brains of people with certain mental illnesses have opened the door for new treatment options.
Francis Crick and James Watson
The deoxyribonucleic acid (DNA) molecule is the genetic blueprint for each cell and ultimately the blueprint that determines every characteristic of a living organism. In 1953 American biochemist James Watson, left, and British biophysicist Francis Crick, right, described the structure of the DNA molecule as a double helix, somewhat like a spiral staircase with many individual steps. Their work was aided by X-ray diffraction pictures of the DNA molecule taken by British biophysicist Maurice Wilkins and British physical chemist Rosalind Franklin. In 1962 Crick, Watson, and Wilkins received the Nobel Prize for their pioneering work on the structure of the DNA molecule.
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The discovery of genes and their role in heredity and disease was one of the most important medical advances in history (see Genetics). In 1953 British biophysicist Francis Crick and American biochemist James Watson identified the double-helix structure of deoxyribonucleic acid (DNA). This discovery helped to explain how DNA carried genetic information. In the 1960s American biochemist Marshall Nirenberg added key details about how DNA determines the structure of proteins.
Indian-born American biochemist Har Gobind Khorana was the first to synthesize a gene in the laboratory in 1970, forging the way for scientists to develop ways to isolate, alter, and clone, or copy, genes. They applied these genetic engineering techniques to the diagnosis and treatment of diseases. Researchers identified genes associated with cancer, heart disease, mental illness, and obesity. With the genes identified, they worked on ways of modifying the genes to treat the disease. Gene therapy emerged as an experimental medical field that used genetically modified genes to treat diseases. In 2003 scientists completed the sequence of the human genome, in which they identified all the genes needed to make a human being (see Human Genome Project).
Correcting Genetic Diseases
Gene therapy may someday be able to cure hereditary diseases, such as hemophilia and cystic fibrosis, which are caused by missing or defective genes. In one type of gene therapy, genetically engineered viruses are used to insert new, functioning genes into the cells of people who are unable to produce certain hormones or proteins necessary for the body to function normally.
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Genetic engineering techniques enabled production of scarce human hormones and other materials for use as drugs. A new biotechnology industry started producing these materials for medical use. Scientists also began genetically modifying sheep and other animals to produce drugs in their milk.
In 1905, British scientist Ernest H. Starling introduced the word hormone to describe substances secreted by the endocrine glands that regulate body functions (see Endocrine System). The discovery of adrenaline, or epinephrine, in 1901 led to identification and isolation of other hormones. One of the most important advances was the discovery of insulin by Canadian scientists Frederick Banting and Charles H. Best and Scottish physiologist John J. Macleod in 1921. For years people with diabetes mellitus used insulin extracted from animal pancreases. In 1981, human insulin produced using biotechnology became available. American physicians made another major advance in endocrinology in 1949. They discovered that cortisone, an adrenal gland hormone, relieved inflammation. New discoveries about human sex hormones later led to the first birth control pills.
Ultrasound, or sound waves with frequencies above detection by the human ear, is commonly used in obstetrics to diagnose both the age and health of the developing fetus. An ultrasound-emitting device called a transducer is placed against the skin of the pregnant woman’s abdomen. The sound waves reflect in varying degrees when they contact tissues of different density and elasticity. The pattern of echoes is detected by the transducer and is converted into a moving image seen on a monitor. Ultrasound is also used in procedures involving the sampling of amniotic fluid or placental tissue. Outside of obstetrics, it is used to detect tumors, damage, or abnormalities in the liver, kidney, ovaries, eyes, and other organs. Because ultrasound waves pass readily through soft tissue but not through bone or gas, the technique cannot be used to scan parts of the body such as the brain, lungs, or intestines.
Alexander Tsiaras/Science Source/Photo Researchers, Inc.
Great advances were made in birth control with the improvement of intrauterine devices in the 1950s and the development of the birth control pill in 1960 by the American biologist Gregory Pincus. By the 1990s long-lasting hormonal implants and contraceptive injections such as Depo-Provera were developed. These options gave women more control in deciding whether to become pregnant. Voluntary sterilization, involving vasectomies in men and tubal sterilization in women, emerged as a popular way of permanent birth control. Unwanted pregnancies, however, remained a serious problem in the late 1990s. Researchers still sought more convenient and safer methods of birth control, including a male birth control pill.
By 1975 physicians were able to diagnose some congenital or inherited diseases before childbirth (see Birth Defects). Doctors take samples of placental cells (see Chorionic Villus Sampling) or of the amniotic fluid around the fetus (see Amniocentesis) to determine whether hereditary blood diseases, Down syndrome, defects of the spine, or other congenital diseases are present. Even the sex of a fetus may be known in advance.
In amniocentesis, a medical procedure generally performed during the fourth month of pregnancy, approximately one ounce of the amniotic fluid surrounding the fetus is drawn off for study. The examination of fetal cells contained in the sample can provide valuable information concerning developmental abnormalities of the fetus.
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In addition to advances in early diagnosis, progress occurred in identifying the causes of some birth defects. Excess alcohol consumption during pregnancy was linked to fetal alcohol syndrome, and inadequate intake of the vitamin folic acid was linked to spina bifida and other neural tube defects.
Advances in treating infertility, which prevents couples from having children, began with the world's first so-called test-tube baby born in the 1980s through in vitro fertilization. Other forms of assisted reproduction soon became available. Researchers in 1997 cloned a lamb from cells taken from an adult ewe. It led to speculation that human cloning could become another option in human reproduction.
False-Color Angiogram of a Healthy Human Heart
Coronary angiography, the X-ray examination of the heart after the injection of a radiopaque dye or contrast medium, is used to detect the presence and extent of coronary disease. The main coronary arteries appear as yellow ribbons across the heart.
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Heart disease emerged as one of the leading causes of death in Western countries by the end of the 20th century. Great advances occurred in diagnosis, treatment, and prevention of this widespread disease.
Diagnosis improved with the widespread use of cardiac catheterization in the 1950s. This procedure involves threading a slender tube into the heart to take measurements and identify blocked arteries. Less invasive diagnostic methods, such as thallium scans in which a special imaging camera detects the movement of thallium in heart muscle, provided additional diagnostic improvements.
These techniques led to a new era in surgical treatment of coronary heart disease, artery blockages that cause most heart attacks. Physicians began treating blocked coronary arteries with a variety of new techniques. The first bypass operation was performed in 1967 and involved the creation of a new route for blood supply to reach blood-starved heart muscles. In balloon angioplasty, developed in 1977, a deflated balloon is inserted into a narrowed artery. The balloon is then inflated at the site of the narrowing to widen it. Other surgical advances included replacement of diseased heart valves with artificial valves; implantation of pacemakers that maintain normal heart rhythm; use of temporary artificial hearts; and better methods for correcting hereditary defects in the heart.
New drugs were developed to treat angina pectoris, the chest pain of heart disease; high blood pressure; dangerous abnormalities in heart rhythm; and high blood cholesterol levels. Studies showed that drug treatment could reduce the risk of a heart attack or stroke. In the 1980s, aspirin went into wide use to prevent blood clots that cause many heart attacks. Emergency medical personnel also began using drugs that dissolve clots and stop a heart attack if given soon after symptoms develop.
Advances have been made in the prevention of heart disease. Studies have identified risk factors such as high blood pressure, high blood cholesterol, cigarette smoking, diabetes, obesity, and lack of exercise. Government health agencies and public health groups began public education programs to help people reduce heart disease risks. These preventive methods seem to be working—according to the American Heart Association, the death rate from coronary heart disease declined 26.3 percent between 1988 and 1998.
A patient undergoes radiation treatment for cancer of the spine. In this procedure the radioisotope cobalt 60 is used as the source of gamma radiation. A high dose of gamma radiation is guided by laser targeting to a localized area of treatment.
Martin Dohrn/Science Source/Photo Researchers, Inc.
Early detection and better treatment have resulted in major improvements in survival of patients with cancer. By 2000, 59 percent of people diagnosed with cancer were alive five years later, compared with only 25 percent in 1940. New drugs, surgical procedures, and ways of treating cancer with X rays and radioactive isotope radiation contributed to the improvement. In the 1990s, physicians used new knowledge about the human immune system to develop immunotherapy for some kinds of cancer, in which the immune system is stimulated to produce antibodies against specific invaders. Another form of immunotherapy is the use of monoclonal antibodies, genetically engineered antibodies that target specific cancer cells.
Screening tests for early detection of cancers of the cervix, prostate, breast, and colon and rectum (see Colorectal Cancer) became widely available. Researchers also made progress in identifying cancer genes that are associated with an increased risk of the disease and developed screening tests for some cancer genes. Advances in gene therapy also offered promise for new cancer treatments.
Health groups placed great emphasis in the second half of the century on cancer prevention through avoiding smoking and eating a diet rich in fresh fruits and vegetables. Despite these advances, the percentage of deaths from cancer increased from about 2 percent in 1900 to about 20 percent in 2000. Much of the rise, however, resulted from an increased proportion of older people, who are more vulnerable to cancer, and from cigarette smoking.
Advances in computer and Internet technologies created new possibilities for doctors and their patients in the early 1990s. Using computers to send live video, sound, and high-resolution images between two distant locations, doctors can easily examine patients in offices thousands of miles away. Rural patients no longer had to make long trips into urban centers to consult specialists.
In telemedicine, a computer fitted with special software and a video camera turns a live video image of a patient into a digital signal. This signal is transmitted over high-speed telephone lines to similar equipment at the doctor’s office, where it is converted back into a format that can be viewed live on a television screen. Telemedicine also includes machines specially designed to measure and record a patient’s vital signs at home, then transmit the information directly to a hospital nursing station. This electronic remote home care enables health care professionals to monitor a patient’s heart rate, temperature, blood pressure, pulse, blood-oxygen levels, and weight several times a day, without the patient ever having to leave home.
In addition to providing a vehicle for doctors and patients in remote locations to interact, telemedicine also enabled doctors in distant locations to share information. Patient charts, X rays, and other diagnostic materials can be transmitted between doctors’ offices. Moreover, doctors in rural areas of the world can observe state-of-the-art medical procedures that they would otherwise have had to travel thousands of miles to witness. Still in its infancy in the late 1990s, telemedicine may one day alleviate some of the regional inequalities inherent in modern medicine, not just between regions of North America, but also between developing countries and urban medical centers in the industrialized world.
Man on Life Support
Life support equipment keeps an elderly man alive at a hospital. Proponents of euthanasia believe that unnecessarily prolonging life in terminally ill patients causes suffering to the patients and their family members. Many societies now permit passive euthanasia, which allows physicians to withhold or withdraw life-sustaining treatment when directed to do so by the patient or an authorized representative.
Jan Halaska/Photo Researchers, Inc.
New medical, reproductive, and genetic technology in the second half of the 20th century led to increased concern about moral issues in medical treatment and research. By the 1990s, medical ethics, or bioethics, emerged as a recognized discipline that involved physicians, nurses, attorneys, theologians, philosophers, and sociologists.
Many bioethics issues involve the possible misuse of genetic engineering technology. The Human Genome Project led to identification of genes that raise an individual's risk of developing cancer, heart disease, mental illness, alcoholism, violent behavior, and other conditions. Tests to detect some of these disease-susceptibility genes became available in the 1990s.
These discoveries led to debate over whether genetic tests should be performed and how the results should be used. Should parents use such tests to screen their unborn infants? If a fetus tested positive, should it be aborted? If a woman tested positive for a breast cancer susceptibility gene, should the information be made available to insurance companies? Do insurers have a right to deny coverage to people with a genetic high risk for serious diseases? Do employers have a right to demand genetic screening tests before hiring people?
Genetic technology also offers the potential of eventually replacing defective genes with normal copies in human sperm and eggs. Some fear it will lead to mandatory eugenics programs, attempts to improve the hereditary traits of individuals or even entire races. Others argue that advances in genetic technology could eliminate defective genes and hereditary diseases from future generations.
An intense discussion about bioethics occurred in 1997 and 1998, after researchers in Scotland cloned the lamb, Dolly, from udder cells from an adult ewe. The experiment showed that it was possible to clone, or produce an exact genetic copy, of an adult mammal. Medical ethicists debate whether cloning of human beings should be permitted, as well as the potential effects on society.
Although abortion became legal in the United States in 1973, it still causes heated debate over the rights of the fetus and the pregnant woman, as well as the question of when a fetus becomes a human being. The availability of RU-486, also known as mifepristone, an inexpensive drug that induces abortion, led to concern that more people would use abortion for birth control. Ethical discussions centered on whether tissue from aborted fetuses should be used in medical research, treatment of disease, and organ transplants.
The right of terminally ill people to receive assistance in dying raised other ethical dilemmas. Physician-assisted suicide came to national attention largely through the efforts of Jack Kevorkian, a Michigan physician who helps people with terminal illnesses commit suicide. Opponents claim it is unethical for physicians to help patients commit suicide. Supporters counter that terminally ill patients have a right to determine the time and manner of their death. While the U.S. Supreme Court in 1997 ruled that states can ban physician-assisted suicide, that same year Oregon voters rejected an effort to repeal their law, the nation's first to legalize physician-assisted suicide.
Mammography is a special X-ray technique that is used to visualize soft tissues of the breast as a means for screening women for breast cancer. This mammogram shows calcification (dense white flecks) in a cancerous tumor. The nipple is to the left. The majority of breast cancers originate in the duct of the mammary, or milk-secreting, gland. The remainder arise in the glands themselves. Most tumors of either type show early evidence of invasive (malignant) behavior, but both may also exist in noninvasive forms.
Kings College Hospital/Science Source/Photo Researchers, Inc.
In the 1960s and 1970s, physicians and medical educators began to recognize a basic flaw in the health care system. Medicine traditionally was concerned with treating disease after symptoms appeared, resulting in treatment that was often very expensive. About 600,000 coronary bypass operations were performed annually in the United States in the 1990s, at a cost of $44,000 each. Medical officials recognized the advantage of preventing disease in the first place, rather than just treating it.
Medical schools began teaching students the importance of disease prevention. Some physicians specialized in a new field, preventive medicine, which emphasized keeping patients healthy. Practicing physicians spent more time counseling patients about smoking, excessive drinking, and other unhealthy practices. They did so by encouraging patients to avoid risk factors for disease; take periodic screening tests that detect disease early; and treat high blood pressure.
Yet by the late 1990s, many people still failed to use preventive services. Studies in 1997 estimated that 30,000 deaths per year could have been prevented if more people were immunized against influenza, pneumococcal pneumonia, and hepatitis B. Likewise, smoking, the leading preventable cause of death in the industrialized world, causes more than 4 million deaths worldwide each year.
Another dramatic change in medicine involved the idea that individuals have an important role in preventing diseases caused by an unhealthy lifestyle. Health care consumers grew more knowledgeable about medicine. Medical pages became a regular feature of major newspapers, news magazines, and television news programs. Some people subscribed to magazines and newsletters devoted entirely to health. Laypeople consulted books, such as the Physician's Desk Reference and The Merck Manual, once used only by professionals. They also tapped health information available on the Internet's World Wide Web (WWW). With this knowledge, consumers sought to become partners with their physicians in deciding the best ways of preventing, diagnosing, and treating disease.
Practitioners of chiropractic believe that many ailments and diseases can be healed by the manual adjustment of bone and tissue. Chiropractors offer non-surgical remedies for back and neck pain, headaches, and other conditions. Chiropractic is also considered a preventative health-care method.
Art Stein/Science Source/Photo Researchers, Inc.
A resurgence of interest developed in the 1990s in medical treatments not fully accepted by conventional medicine or biomedicine, which requires stringent scientific proof of safety and effectiveness before accepting a treatment. Such evidence is lacking for many approaches used in the medical systems and treatments known as alternative medicine in the United States. In Europe, these same approaches often are called complementary medicine. Growing public interest in nontraditional treatments led the NIH to open the National Center for Complementary and Alternative Medicine (formerly the Office of Alternative Medicine) in 1992, which encourages research on alternative medicine. The number of Americans using an alternative therapy rose from 33 percent in 1990 to more than 42 percent in 1997.
Alternative medicine emphasizes improving the quality of life for people with chronic illness; disease prevention; and treatments for conditions that conventional medicine cannot adequately control, such as arthritis, chronic pain, allergies, cancer, heart disease, and depression. A cornerstone of alternative medicine is the idea that the mind influences the health of the body.
Alternative medical systems include chiropractic, holistic medicine, and homeopathy. Chiropractors treat disease with spinal manipulation, massage, diet, and many other techniques. Holistic healers emphasize treatment of the whole person, including body, mind, emotions, spirit, and interactions with the family and environment. Homeopathic healers use substances that cause the very symptoms being treated. When treating a headache or nausea, for example, homeopathic healers administer herbs that in large doses cause headache or nausea. But they use very small doses that cause the patient no discomfort.
Specific alternative medical treatments include aromatherapy, inhaling oils from aromatic plants; massage techniques, including Rolfing and reflexology; biofeedback; iridology, in which the eye is used to diagnose certain diseases; and acupuncture. Some approaches, including chiropractic manipulation and acupuncture, have gained greater acceptance in conventional medicine. Some conventional biomedical studies have concluded that chiropractic manipulation is effective for low-back pain. A 1997 NIH report gave acupuncture limited endorsement for certain medical uses.
Organizations that educate the public about health fraud and quackery expressed concern about growing interest in some alternative medicine treatments. They emphasized the importance of receiving a conventional medical diagnosis, and exploring standard treatment options, before turning to alternative medicine.
The United States spends more on health care than any other country in the world. Spending in 1998 averaged $4,094 per person, compared to $2,689 in 1990, $1,052 in 1980, $341 in 1970, and $141 in 1960. The only countries that approached the United States in per capita spending were Switzerland ($2,412), Germany ($2,222), Luxembourg ($2,206), and Canada ($2,002). In the United States, spending on health care exceeded $1.1 trillion in 1998, up from $699.4 billion in 1990, $247.3 in 1980, $73.2 in 1970, and $26.9 billion in 1960.
Yet millions of Americans still do not have adequate access to health care because they lack insurance coverage. An estimated 44.2 million people had no health insurance in 1998. Access is a greater problem in the United States because most other industrialized countries have national health insurance systems that cover medical expenses. Since the 1960s, the United States Congress established and expanded programs to improve access to care. Medicare, the major program, covered about 38 million people over age 65 and people with disabilities in 1997. Another was Medicaid, a federal-state program that covers low-income people. During the 1990s, Congress considered and rejected proposals to establish a national health insurance system or extend government health care benefits to more people. The high costs of such a program were among the reasons for rejection.
Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.
Human Anatomy Illustrations
Learn about the ten systems in the human body.
Booktionary Corporation. All Rights Reserved.
Circulatory System, or cardiovascular system, in humans, the combined function of the heart, blood, and blood vessels to transport oxygen and nutrients to organs and tissues throughout the body and carry away waste products. Among its vital functions, the circulatory system increases the flow of blood to meet increased energy demands during exercise and regulates body temperature. In addition, when foreign substances or organisms invade the body, the circulatory system swiftly conveys disease-fighting elements of the immune system, such as white blood cells and antibodies, to regions under attack. Also, in the case of injury or bleeding, the circulatory system sends clotting cells and proteins to the affected site, which quickly stop bleeding and promote healing.
Human Circulatory System
The human circulatory system is composed of the muscular heart and an intricate network of elastic blood vessels known as arteries, veins, and capillaries. These structures work together to circulate blood throughout the body, in the process delivering life-preserving oxygen and nutrients to tissue cells while also removing waste products.
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The heart, blood, and blood vessels are the three structural elements that make up the circulatory system. The heart is the engine of the circulatory system. It is divided into four chambers: the right atrium, the right ventricle, the left atrium, and the left ventricle. The walls of these chambers are made of a special muscle called myocardium, which contracts continuously and rhythmically to pump blood. The pumping action of the heart occurs in two stages for each heart beat: diastole, when the heart is at rest; and systole, when the heart contracts to pump deoxygenated blood toward the lungs and oxygenated blood to the body. During each heartbeat, typically about 60 to 90 ml (about 2 to 3 oz) of blood are pumped out of the heart. If the heart stops pumping, death usually occurs within four to five minutes.
Heart and Blood Circulation
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Blood consists of three types of cells: oxygen-bearing red blood cells, disease-fighting white blood cells, and blood-clotting platelets, all of which are carried through blood vessels in a liquid called plasma. Plasma is yellowish and consists of water, salts, proteins, vitamins, minerals, hormones, dissolved gases, and fats.
Constituents of Blood
In an average healthy person, approximately 45 percent of the blood volume is cells, among them red cells (the majority), white cells, and platelets. A clear, yellowish fluid called plasma makes up the rest of blood. Plasma, 95 percent of which is water, also contains nutrients such as glucose, fats, proteins, and the amino acids needed for protein synthesis, vitamins, and minerals. The level of salt in plasma is about equal to that of sea water. The test tube on the right has been centrifuged to separate plasma and packed cells by density.
Martin M. Rotker/Science Source/Photo Researchers, Inc.
Three types of blood vessels form a complex network of tubes throughout the body. Arteries carry blood away from the heart, and veins carry it toward the heart. Capillaries are the tiny links between the arteries and the veins where oxygen and nutrients diffuse to body tissues. The inner layer of blood vessels is lined with endothelial cells that create a smooth passage for the transit of blood. This inner layer is surrounded by connective tissue and smooth muscle that enable the blood vessel to expand or contract. Blood vessels expand during exercise to meet the increased demand for blood and to cool the body. Blood vessels contract after an injury to reduce bleeding and also to conserve body heat.
Arteries have thicker walls than veins to withstand the pressure of blood being pumped from the heart. Blood in the veins is at a lower pressure, so veins have one-way valves to prevent blood from flowing backwards away from the heart. Capillaries, the smallest of blood vessels, are only visible by microscope—ten capillaries lying side by side are barely as thick as a human hair. If all the arteries, veins, and capillaries in the human body were placed end to end, the total length would equal more than 100,000 km (more than 60,000 mi)—they could stretch around the earth nearly two and a half times.
The arteries, veins, and capillaries are divided into two systems of circulation: systemic and pulmonary. The systemic circulation carries oxygenated blood from the heart to all the tissues in the body except the lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to the heart. The pulmonary circulation carries this spent blood from the heart to the lungs. In the lungs, the blood releases its carbon dioxide and absorbs oxygen. The oxygenated blood then returns to the heart before transferring to the systemic circulation.
Only in the past 400 years have scientists recognized that blood moves in a cycle through the heart and body. Before the 17th century, scientists believed that the liver creates new blood, and then the blood passes through the heart to gain warmth and finally is soaked up and consumed in the tissues. In 1628 English physician William Harvey first proposed that blood circulates continuously. Using modern methods of observation and experimentation, Harvey noted that veins have one-way valves that lead blood back to the heart from all parts of the body. He noted that the heart works as a pump, and he estimated correctly that the daily output of fresh blood is more than seven tons. He pointed out the absurdity of the old doctrine, which would require the liver to produce this much fresh blood daily. Harvey’s theory was soon proven correct and became the cornerstone of modern medical science.
The heart ejects oxygen-rich blood under high pressure out of the heart’s main pumping chamber, the left ventricle, through the largest artery, the aorta. Smaller arteries branch off from the aorta, leading to various parts of the body. These smaller arteries in turn branch out into even smaller arteries, called arterioles. Branches of arterioles become progressively smaller in diameter, eventually forming the capillaries. Once blood reaches the capillary level, blood pressure is greatly reduced.
Capillaries have extremely thin walls that permit dissolved oxygen and nutrients from the blood to diffuse across to a fluid, known as interstitial fluid, that fills the gaps between the cells of tissues or organs. The dissolved oxygen and nutrients then enter the cells from the interstitial fluid by diffusion across the cell membranes. Meanwhile, carbon dioxide and other wastes leave the cell, diffuse through the interstitial fluid, cross the capillary walls, and enter the blood. In this way, the blood delivers nutrients and removes wastes without leaving the capillary tube.
After delivering oxygen to tissues and absorbing wastes, the deoxygenated blood in the capillaries then starts the return trip to the heart. The capillaries merge to form tiny veins, called venules. These veins in turn join together to form progressively larger veins. Ultimately, the veins converge into two large veins: the inferior vena cava, bringing blood from the lower half of the body; and the superior vena cava, bringing blood from the upper half. Both of these two large veins join at the right atrium of the heart.
Because the pressure is dissipated in the arterioles and capillaries, blood in veins flows back to the heart at very low pressure, often running uphill when a person is standing. Flow against gravity is made possible by the one-way valves, located several centimeters apart, in the veins. When surrounding muscles contract, for example in the calf or arm, the muscles squeeze blood back toward the heart. If the one-way valves work properly, blood travels only toward the heart and cannot lapse backward. Veins with defective valves, which allow the blood to flow backward, become enlarged or dilated to form varicose veins.
In pulmonary circulation, deoxygenated blood returning from the organs and tissues of the body travels from the right atrium of the heart to the right ventricle. From there it is pushed through the pulmonary artery to the lung. In the lung, the pulmonary artery divides, forming the pulmonary capillary region of the lung. At this site, microscopic vessels pass adjacent to the alveoli, or air sacs of the lung, and gases are exchanged across a thin membrane: oxygen crosses the membrane into the blood while carbon dioxide leaves the blood through this same membrane. Newly oxygenated blood then flows into the pulmonary veins, where it is collected by the left atrium of the heart, a chamber that serves as collecting pool for the left ventricle. The contraction of the left ventricle sends blood into the aorta, completing the circulatory loop. On average, a single blood cell takes roughly 30 seconds to complete a full circuit through both the pulmonary and systemic circulation.
In addition to oxygen, the circulatory system also transports nutrients derived from digested food to the body. These nutrients enter the bloodstream by passing through the walls of the intestine. The nutrients are absorbed through a network of capillaries and veins that drain the intestines, called the hepatic portal circulation. The hepatic portal circulation carries the nutrients to the liver for further metabolic processing. The liver stores a variety of substances, such as sugars, fats, and vitamins, and releases these to the blood as needed. The liver also cleans the blood by removing waste products and toxins. After hepatic portal blood has crossed the liver cells, veins converge to form the large hepatic vein that joins the vena cava near the right atrium.
The circulatory system plays an important role in regulating body temperature. During exercise, working muscles generate heat. The blood supplying the muscles with oxygen and nutrients absorbs much of this heat and carries it away to other parts of the body. If the body gets too warm, blood vessels near the skin enlarge to disperse excess heat outward through the skin. In cold environments, these blood vessels constrict to retain heat.
The circulatory system works in tandem with the endocrine system, a collection of hormone-producing glands. These glands release chemical messengers, called hormones, directly into the bloodstream to be transported to specific organs and tissues. Once they reach their target destination, hormones regulate the body’s rate of metabolism, growth, sexual development, and other functions.
The circulatory system also works with the immune system and the coagulation system. The immune system is a complex system of many types of cells that work together to combat diseases and infections. Disease-fighting white blood cells and antibodies circulate in the blood and are transported to sites of infection by the circulatory system. The coagulation system is composed of special blood cells, called platelets, and special proteins, called clotting factors, that circulate in the blood. Whenever blood vessels are cut or torn, the coagulation system works rapidly to stop the bleeding by forming clots.
Other organs support the circulatory system. The brain and other parts of the nervous system constantly monitor blood circulation, sending signals to the heart or blood vessels to maintain constant blood pressure. New blood cells are manufactured in the bone marrow. Old blood cells are broken down in the spleen, where valuable constituents, such as iron, are recycled. Metabolic waste products are removed from the blood by the kidneys, which also screen the blood for excess salt and maintain blood pressure and the body’s balance of minerals and fluids.
Blood Pressure Check
A patient’s blood pressure is checked through the use of a sphygmomanometer. A rubber cuff is wrapped around the upper arm and inflated, compressing the artery to stop the blood flow. A stethoscope is placed on the arm to listen for the return of the blood as the cuff gradually deflates. Readings taken at the point when the blood forcefully returns and when it is flowing smoothly again determine the blood pressure.
John Greim/Medichrome/The Stock Shop
The pressure generated by the pumping action of the heart propels the blood to the arteries. In order to maintain an adequate flow of blood to all parts of the body, a certain level of blood pressure is needed. Blood pressure, for instance, enables a person to rise quickly from a horizontal position without blood pooling in the legs, which would cause fainting from deprivation of blood to the brain. Normal blood pressure is regulated by a number of factors, such as the contraction of the heart, the elasticity of arterial walls, blood volume, and resistance of blood vessels to the passage of blood.
Blood pressure is measured using an inflatable device with a gauge called a that is wrapped around the upper arm. Blood pressure is measured during systole, the active pumping phase of the heart, and diastole, the resting phase between heartbeats. Systolic and diastolic pressures are measured in units of millimeters of mercury (abbreviated mm Hg) and displayed as a ratio. Blood pressure varies between individuals and even during the normal course of a day in response to emotion, exertion, sleep, and other physical and mental changes. Normal blood pressure is less than 120/80 mm Hg, in which 120 describes systolic pressure and 80 describes diastolic pressure. Higher blood pressures that are sustained over a long period of time may indicate hypertension, a damaging circulatory condition. Lower blood pressures could signal shock from heart failure, dehydration, internal bleeding, or blood loss.
Trepanning, the procedure of cutting a hole in the skull, is the earliest known medical operation. Some anthropologists believe that trepanning was performed on people with mental illnesses to drive out evil spirits from their heads. This skull dates from the Inca civilization.
Daniele Pellegrini/Photo Researchers, Inc.
Evidence for trepanning, the surgical procedure of cutting a hole in the skull, dates back 4,000 to 5,000 years. Some anthropologists speculate that Stone Age societies performed trepanning on people with mental illnesses to release evil spirits or demons from their heads. In the absence of written records, however, it is impossible to know why the operation was performed.
The Greek physician Hippocrates was one of the first scholars to challenge the notion that disease was punishment sent from the gods. He believed that all illnesses, including mental illnesses, had natural origins.
The literature of ancient Greece and Rome contains evidence of the belief that spirits or demons cause mental illness. In the 5th century bc the Greek historian Herodotus wrote an account of a king who was driven mad by evil spirits. The legend of Hercules describes how, driven insane by a curse, he killed his own children. The Roman poets Virgil and Ovid repeated these themes in their works. The early Babylonian, Chinese, and Egyptian civilizations also viewed mental illness as possession, and used exorcism—which sometimes involved beatings, restraint, and starvation—to drive the evil spirits from their victim.
Not all ancient scholars agreed with this theory of mental illness. The Greek physician Hippocrates believed that all illnesses, including mental illnesses, had natural origins. For example, he rejected the prevailing notion that epilepsy had its origins in the divine or sacred, viewing it as a disease of the brain. Hippocrates classified mental illnesses into categories that included mania, melancholia (depression), and phrenitis (brain fever), and he advocated humane treatment that included rest, bathing, exercise, and dieting. The Greek philosopher Plato, although adhering to a somewhat supernatural view of mental illness, believed that childhood experiences shaped adult behaviors, anticipating modern psychodynamic theories by more than 2000 years.
The Middle Ages in Europe, from the fall of the Roman empire in the 5th century ad to about the 15th century, was a period in which religious beliefs, specifically Christianity, dominated concepts of mental illness. Much of society believed that mentally ill people were possessed by the devil or demons, or accused them of being witches and infecting others with madness (see Witchcraft). Thus, instead of receiving care from physicians, the mentally ill became objects of religious inquisition and barbaric treatment. On the other hand, some historians of medicine cite evidence that even in the Middle Ages, many people believed mental illness to have its basis in physical and psychological disturbances, such as imbalances in the four bodily humors (blood, black bile, yellow bile, and phlegm), poor diet, and grief.
The Islamic world of North Africa, Spain, and the Middle East generally held far more humane attitudes toward people with mental illnesses. Following the belief that God loved insane people, communities began establishing asylums beginning in the 8th century ad, first in Baghdād and later in Cairo, Damascus, and Fez. The asylums offered patients special diets, baths, drugs, music, and pleasant surroundings.
The Renaissance, which began in Italy in the 14th century and spread throughout Europe in the 16th and 17th centuries, brought both deterioration and progress in perceptions of mental illness. On the one hand, witch-hunts and executions escalated throughout Europe, and the mentally ill were among those persecuted. The infamous Malleus Maleficarum,which served as a handbook for inquisitors, claimed that witches could be identified by delusions, hallucinations, or other peculiar behavior. To make matters worse, many of the most eminent physicians of the time fervently advocated these beliefs.
On the other hand, some scholars vigorously protested these supernatural views and called renewed attention to more rational explanations of behavior. In the early 16th century, for example, the Swiss physician Paracelsus returned to the views of Hippocrates, asserting that mental illnesses were due to natural causes. Later in the century, German physician Johann Weyer argued that witches were actually mentally disturbed people in need of humane medical treatment.
Pinel Frees the Insane
French physician Philippe Pinel supervises the unchaining of mentally ill patients in 1794 at La Salpêtrière, a large hospital in Paris. Pinel believed in treating mentally ill people with compassion and patience, rather than with cruelty and violence. This painting, Pinel Frees the Insane from Their Chains, was completed by French artist Tony Robert-Fleury in 1876.
Belzeaux/Photo Researchers, Inc.
During the Age of Enlightenment, in the 18th and early 19th centuries, people with mental illnesses continued to suffer from poor treatment. For the most part, they were left to wander the countryside or committed to institutions. In either case, conditions were generally wretched. One mental hospital, the Hospital of Saint Mary of Bethlehem in London, England, became notorious for its noisy, chaotic conditions and cruel treatment of patients (see Bedlam).
The Hospital of Saint Mary of Bethlehem, a London mental hospital commonly known as Bedlam, sold admission tickets to the public in the 18th century, becoming a popular tourist attraction. In this engraving by English artist William Hogarth, part of his series A Rake’s Progress (1735), two women (seen in the background) tour the hospital, watching the mentally ill patients for their amusement. The hospital became notorious for its miserable conditions and cruel treatment of patients.
Art Resource, NY
Yet as the public’s awareness of such conditions grew, improvements in care and treatment began to appear. In 1789 Vincenzo Chiarugi, superintendent of a mental hospital in Florence, Italy, introduced hospital regulations that provided patients with high standards of hygiene, recreation and work opportunities, and minimal restraint. At nearly the same time, Jean-Baptiste Pussin, superintendent of a ward for “incurable” mental patients at La Bicêtre hospital in Paris, France, forbade staff to beat patients and released patients from shackles. Philippe Pinel continued these reforms upon becoming chief physician of La Bicêtre’s ward for the mentally ill in 1793. Pinel began to keep case histories of patients and developed the concept of “moral treatment,” which involved treating patients with kindness and sensitivity, and without cruelty or violence. In 1796 a Quaker named William Tuke established the York Retreat in rural England, which became a model of compassionate care. The retreat enabled people with mental illnesses to rest peacefully, talk about their problems, and work. Eventually these humane techniques became widespread in Europe.
In 1908, after his release from a mental asylum, Clifford Whittingham Beers wrote A Mind That Found Itself, which exposed the poor conditions he had suffered while confined. He went on to establish several organizations dedicated to the promotion of mental health reforms in the United States.
Library of Congress
People living in the colonies of North America in the 17th and 18th centuries generally explained bizarre or deviant behavior as God’s will or the work of the devil. Some people with mental illnesses received care from their families, but most were jailed or confined in almshouses with the poor and infirm. By the mid-18th century, however, American physicians came to view mental illnesses as diseases of the brain, and advocated specialized facilities to treat the mentally ill. The Pennsylvania Hospital in Philadelphia, which opened in 1752, became the first hospital in the American colonies to admit people with mental illnesses, housing them in a separate ward. However, in the hospital’s early years, mentally ill patients were chained to the walls of dark, cold cells.
In the 1780s American physician Benjamin Rush instituted changes at the Pennsylvania Hospital that greatly improved conditions for mentally ill patients. Although he endorsed the continued use of restraints, punishment, and bleeding, he also arranged for heat and better ventilation in the wards, separation of violent patients from other patients, and programs that offered work, exercise, and recreation to patients. Between 1817 and 1828, following the examples of Tuke and Pinel, a number of institutions opened that devoted themselves exclusively to the care of mentally ill people. The first private mental hospital in the United States was the Asylum for the Relief of Persons Deprived of the Use of Their Reason (now Friends Hospital), opened by Quakers in 1817 in what is now Philadelphia. Other privately established institutions soon followed, and state-sponsored hospitals—in Kentucky, New York, Virginia, and South Carolina—-opened beginning in 1824.
American reformer Dorothea Dix championed the causes of prison inmates, the mentally ill, and the destitute. Horrified by the conditions provided for the mentally ill in Massachusetts, Dix successfully petitioned the state government for improvements in 1843. She was directly responsible for building or enlarging 32 mental hospitals in North America, Europe, and Japan.
THE BETTMANN ARCHIVE
Nevertheless, circumstances for most mentally ill people in the United States, especially those who were poor, remained dreadful. In 1841 Dorothea Dix, a Boston schoolteacher, began a campaign to make the public aware of the plight of mentally ill people. By 1880, as a direct result of her efforts, 32 psychiatric hospitals for the poor had opened. Increasingly, society viewed psychiatric institutions as the most appropriate form of care for people with mental illnesses. However, by the late 19th century, conditions in these institutions had deteriorated. Overcrowded and understaffed, psychiatric hospitals had shifted their treatment approach from moral therapy to warehousing and punishment. In 1908 Clifford Whittingham Beers aroused new concern for mentally ill individuals with the publication of A Mind That Found Itself, an account of his experiences as a mental patient. In 1909 Beers founded the National Committee for Mental Hygiene, which worked to prevent mental illness and ensure humane treatment of the mentally ill.
Following World War II (1939-1945), a movement emerged in the United States to reform the system of psychiatric hospitals, in which hundreds of thousands of mentally ill persons lived in isolation for years or decades. Many mental health professionals—seeing that large state institutions caused as much, if not more, harm to patients than mental illnesses themselves—came to believe that only patients with severe symptoms should be hospitalized. In addition, the development in the 1950s of antipsychotic drugs, which helped to control bizarre and violent behavior, allowed more patients to be treated in the community. In combination, these factors led to the deinstitutionalization movement: the release, over the next four decades, of hundreds of thousands of patients from state mental hospitals. In 1950, 513,000 patients resided in these institutions. By 1965 there were 475,000, and by 1990 state mental hospitals housed only 92,000 patients on any given night. Many patients who were released returned to their families, although many were transferred to questionable conditions in nursing homes or board-and-care homes. Many patients had no place to go and began to live on the streets.
The National Mental Health Act of 1946 created the National Institute of Mental Health as a center for research and funding of research on mental illness. In 1955 Congress created a commission to investigate the state of mental health care, treatment, and prevention. In 1963, as a result of the commission’s findings, Congress passed the Community Mental Health Centers Act, which authorized the construction of community mental health centers throughout the country. Implementation of these centers was not as extensive as originally planned, and many people with severe mental illnesses failed to receive care of any kind.
One of the most important developments in the field of mental health in the United States has been the establishment of advocacy and support groups. The National Alliance for the Mentally Ill (NAMI), one of the most influential of these groups, was founded in 1972. NAMI’s goal is to improve the lives of people with severe mental illnesses and their families by eliminating discrimination in housing and employment and by improving access to essential treatments and programs.
During the 1980s, all levels of government in the United States cut back on funding for social services. For example, the Social Security Administration discontinued benefits for approximately 300,000 people between 1981 and 1983. Of these, an estimated 100,000 were people with mental illnesses. Although the government eventually restored Social Security benefits to many of these people, the interruption of services caused widespread hardship.
The emergence of managed care in the 1990s as a way to contain health care costs had a tremendous impact on mental health care in the United States. Health insurance companies and health maintenance organizations increasingly scrutinized the effectiveness of various psychotherapies and drug treatments and put stricter limits on mental health care. In response to these restrictions, Congress passed the Mental Health Parity Act of 1996. This law required private medical plans that offer mental health coverage to set equal yearly and lifetime payment limits for coverage of both mental and physical illnesses.
In 1997 the U.S. Equal Employment Opportunity Commission issued new guidelines intended to prevent discrimination against people with mental illnesses in the workplace. The rules, based on the Americans with Disabilities Act of 1990, prohibit employers from asking job applicants if they have a history of mental illness and require employers to provide reasonable accommodations to workers with mental illnesses.
In recent years international agencies, led by the World Health Organization (WHO) of the United Nations (UN) have developed mental health policies that seek to reduce the huge burden of mental illness worldwide. These agencies are working to improve the quality of mental health services in Africa, Asia, Latin America, the Middle East, and elsewhere by educating governments on prevention and treatment of mental illness and on the rights of the mentally ill.
Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.