The Origins of Biomedical Science

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Objectives

When you have completed this section, you should be able to

• give examples of how modern biomedical science emerged from an era of superstition and authoritarianism; and

• describe the contributions of some key people who helped to bring about this transformation.

Health science has progressed far more in the last 25 years than in the 2,500 years before that, but the field did not spring up overnight. It is built upon centuries of thought and controversy, triumph and defeat. We cannot fully appreciate its present state without understanding its past—people who had the curiosity to try new things, the vision to look at human form and function in new ways, and the courage to question authority.

The Beginnings of Medicine

As early as 3,000 years ago, physicians in Mesopotamia and Egypt treated patients with herbal drugs, salts, physical therapy, and faith healing. The "father of medicine," however, is usually considered to be the Greek physician

Chapter 1 Major Themes of Anatomy and Physiology 3

Hippocrates (c. 460-c. 375 B.C.E.). He and his followers established a code of ethics for physicians, the Hippo-cratic Oath, that is still recited in modern form by many graduating medical students. Hippocrates urged physicians to stop attributing disease to the activities of gods and demons and to seek their natural causes, which could afford the only rational basis for therapy. Aristotle (384-322 b.c.e.) believed that diseases and other natural events could have either supernatural causes, which he called theologi, or natural ones, which he called physici or physiologi. We derive such terms as physician and physiology from the latter. Until the nineteenth century, physicians were called "doctors of physic." In his anatomy book, Of the Parts of Animals, Aristotle tried to identify unifying themes in nature. Among other points, he argued that complex structures are built from a smaller variety of simple components—a perspective that we will find useful later in this chapter.

_Think About It_

When you have completed this chapter, discuss the relevance of Aristotle's philosophy to our current thinking about human structure.

Claudius Galen (129-c. 199), physician to the Roman gladiators, wrote the most noteworthy medical textbook of the ancient era—a book that was worshiped to excess by medical professors for centuries to follow. Cadaver dissection was banned in Galen's time because of some horrid excesses that preceded him, including dissection of living slaves and prisoners merely to satisfy an anatomist's curiosity or to give a public demonstration. Galen was limited to learning anatomy from what he observed in treating gladiators' wounds and by dissecting pigs, monkeys, and other animals. Galen saw science as a process of discovery, not as a body of fact to be taken on faith. He warned that even his own books could be wrong, and advised his followers to trust their own observations more than they trusted any book. Unfortunately, his advice was not heeded. For nearly 1,500 years, medical professors dogmatically taught what they read in Aristotle and Galen, and few dared to question the authority of these "ancient masters."

The Birth of Modern Medicine

Medical science advanced very little during the Middle Ages. Even though some of the most famous medical schools of Europe were founded during this era, the professors taught medicine primarily as a dogmatic commentary on Galen and Aristotle, not as a field of original research. Medieval medical illustrations were crude representations of the body that served more to decorate a page than to depict the body realistically (fig. 1.2). Some were astrological charts that showed which sign of the

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Form and Function, Third Edition

4 Part One Organization of the Body

4 Part One Organization of the Body

Medieval Medical Illustration Pregnant
Figure 1.2 Medieval Medical Illustration. This figure depicts a pregnant woman with a fetus in the uterus and shows the heart, lungs, arteries, and digestive tract.

zodiac was thought to influence each organ of the body. From such pseudoscience came the word influenza, Italian for influence.

Free inquiry was less inhibited in the Muslim world than in Christendom. Ibn Sina (980-1037), known in the West as Avicenna or "the Galen of Islam," studied Galen and Aristotle, combined their findings with original discoveries, and questioned authority when the evidence demanded it. Muslim medicine soon became superior to Western medicine, and Avicenna's textbook, The Canon of Medicine, became the leading authority in European medical schools until the sixteenth century.

Modern medicine began around the sixteenth century in the innovative minds of such people as the anatomist Andreas Vesalius and the physiologist William Harvey. Andreas Vesalius (1514-64) taught anatomy in Italy. In his time, cadaver dissection had resumed for the purpose of autopsies and gradually found its way into the training of medical students throughout Europe. Dissection was an unpleasant business, however, and most professors considered it beneath their dignity. In these days before refrigeration or embalming, the odor from the decaying cadaver was unbearable. Dissections were conducted outdoors in a nonstop 4-day race against decay. Bleary medical students had to fight the urge to vomit, lest they incur the wrath of an overbearing professor. Professors typically sat in an elevated chair, the cathedra, reading dryly from Galen or Aristotle while a lower-ranking barber-surgeon removed putrefying organs from the cadaver and held them up for the students to see. Barbering and surgery were considered to be "kindred arts of the knife"; today's barber poles date from this era, their red and white stripes symbolizing blood and bandages.

Vesalius broke with tradition by coming down from the cathedra and doing the dissections himself. He was quick to point out that much of the anatomy in Galen's books was wrong, and he was the first to publish accurate illustrations for teaching anatomy (fig. 1.3). When others began to plagiarize his illustrations, Vesalius published the first atlas of anatomy, De Humani Corporis Fabrica (On the Structure of the Human Body), in 1543. This book began a rich tradition of medical illustration that has been handed down to us through such milestones as Gray's Anatomy (1856) and the vividly illustrated atlases and textbooks of today.

Anatomy preceded physiology and was a necessary foundation for it. What Vesalius was to anatomy, the Englishman William Harvey (1578-1657) was to physiology. Harvey is remembered especially for a little book he published in 1628, On the Motion of the Heart and Blood in Animals. Authorities before him believed that digested food traveled to the liver, turned into blood, and then traveled through the veins to organs that consumed it. Harvey measured cardiac output in snakes and other animals, however, and concluded that the amount of food eaten could not possibly account for so much blood. Thus, he inferred that blood must be recycled—pumped out of the heart by way of arteries and returned to the heart by way of veins. Capillaries, the connections between arteries and veins, had not been discovered yet, but Harvey predicted their existence.

Modern medicine also owes an enormous debt to two inventors from this era. Antony van Leeuwenhoek (an-TOE-nee vahn LAY-wen-hook) (1632-1723), a Dutch textile merchant, was the first to invent a microscope capable of visualizing single cells. In order to examine the weave of fabrics more closely, he ground a beadlike lens and mounted it in a metal plate equipped with a movable specimen clip (fig. 1.4). This simple (single-lens) microscope magnified objects 200 to 300 times. Out of curiosity, Leeuwenhoek examined a drop of lake water and was astonished to find a variety of microorganisms—"little animalcules," he called them, "very prettily a-swimming."

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Andreas Vesalius
Figure 1.3 The Art of Vesalius. Andreas Vesalius revolutionized medical illustration with the comparatively realistic art prepared for his 1543 book, De Humani Corporis Fabrica.

He went on to observe practically everything he could get his hands on, including blood cells, blood capillaries, sperm, and muscular tissue. Probably no one in history had looked at nature in such a revolutionary way. Leeuwenhoek opened the door to an entirely new understanding of human structure and the causes of disease. He was praised at first, and reports of his observations were eagerly received by scientific societies, but this public enthusiasm did not last. By the end of the seventeenth century, the microscope was treated as a mere toy for the upper classes, as amusing and meaningless as a kaleidoscope. Leeuwenhoek had even become the brunt of satire.

Leeuwenhoek's most faithful admirer was the Englishman Robert Hooke (1635-1703), who developed the first

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Lens

Specimen holder

Focusing screw

Lens

Specimen holder

Focusing screw

Leeuwenhoek Microscope

Figure 1.4 Leeuwenhoek's Simple Microscope. (a) Modern replica. (b) Viewing a specimen with a Leeuwenhoek microscope.

Figure 1.4 Leeuwenhoek's Simple Microscope. (a) Modern replica. (b) Viewing a specimen with a Leeuwenhoek microscope.

practical compound microscope—a tube with a lens at each end. The second lens further magnified the image produced by the first (fig. 1.5a). Hooke invented many of the features found in microscopes used today: a stage to hold the specimen, an illuminator, and coarse and fine focus controls. His microscopes produced poor images with blurry edges (spherical aberration) and rainbow-colored distortions (chromatic aberration), but poor images were better than none. Although Leeuwenhoek was the first to see cells,

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Physiology: The Unity of Anatomy and Physiology Companies, 2003 Form and Function, Third Edition

6 Part One Organization of the Body

6 Part One Organization of the Body

Mcgraw Hill Wonders Focus Wall
Figure 1.5 Hooke's Compound Microscope. (a) The compound microscope had a lens at each end of a tubular body. (b) Hooke's drawing of cork cells, showing the thick cell walls characteristic of plants.

Hooke named them. In 1663, he observed thin shavings of cork with his microscope and observed that they "consisted of a great many little boxes," which he called cells after the cubicles of a monastery (fig. 1.5b). He published these observations in his book, Micrographia, in 1665.

In nineteenth-century Germany, Carl Zeiss (1816-88) and his business partner, physicist Ernst Abbe (1840-1905), greatly improved the compound microscope, adding the condenser and developing superior optics that reduced chromatic and spherical aberration. Chapter 3 describes some more recently invented types of microscopes. With improved microscopes, biologists began eagerly examining a wider variety of specimens. By 1839, botanist Matthias Schleiden (1804-81) and zoologist Theodor Schwann (1810-82) concluded that all organisms were composed of cells. This was the first tenet of the cell theory, added to by later biologists and summarized in chapter 3. The cell theory was perhaps the most important breakthrough in biomedical history, because all functions of the body are now interpreted as the effects of cellular activity.

Although the philosophical foundation for modern medicine was largely established by the time of Leeuwen-

hoek, Hooke, and Harvey, clinical practice was still in a dismal state. Few doctors attended medical school or received any formal education in basic science or human anatomy. Physicians tended to be ignorant, ineffective, and pompous. Their practice was heavily based on expelling imaginary toxins from the body by bleeding their patients or inducing vomiting, sweating, or diarrhea. They performed operations with dirty hands and instruments, spreading lethal infections from one patient to another. Fractured limbs often became gangrenous and had to be amputated, and there was no anesthesia to lessen the pain. Disease was still widely attributed to demons and witches, and many people felt they would be interfering with God's will if they tried to treat it.

Living in a Revolution

This short history brings us only to the threshold of modern biomedical science; it stops short of such momentous discoveries as the germ theory of disease, the mechanisms of heredity, and the structure of DNA. In the twentieth century, basic biology and biochemistry have given us a much deeper understanding of how the body works. Technological advances such as medical imaging (see insight 1.5, p. 22) have enhanced our diagnostic ability and life-support strategies. We have witnessed monumental developments in chemotherapy, immunization, anesthesia, surgery, organ transplants, and human genetics. By the close of the twentieth century, we had discovered the chemical "base sequence" of every human gene and begun using gene therapy to treat children born with diseases recently considered incurable. As future historians look back on the turn of this century, they may exult about the Genetic Revolution in which you are now living.

Several discoveries of the nineteenth and twentieth centuries, and the men and women behind them, are covered in short historical sketches in later chapters. Yet, the stories told in this chapter are different in a significant way. The people discussed here were pioneers in establishing the scientific way of thinking. They helped to replace superstition with an appreciation of natural law. They bridged the chasm between mystery and medication. Without this intellectual revolution, those who followed could not have conceived of the right questions to ask, much less a method for answering them.

Before You Go On

Answer the following questions to test your understanding of the preceding section:

1. In what way did the followers of Galen disregard his advice? How does Galen's advice apply to you?

2. Describe two ways in which Vesalius improved medical education and set standards that remain relevant today.

3. How is our concept of human form and function today affected by inventors from Leeuwenhoek to Zeiss?

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Physiology: The Unity of Anatomy and Physiology Companies, 2003 Form and Function, Third Edition

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Responses

  • Roisin
    How did galen's followers disregard his advice?
    8 years ago
  • monika
    How modern biomedical science emerged from an era of superstition and authoritarianism?
    8 years ago
  • feorie
    How is our idea of human form and function today affected by inventors from Hooke to Zeiss?
    8 years ago
  • ines
    How is our concept of human form and function today affected by inventors from hooke to zeiss?
    8 years ago
  • Maarit
    What did van leeuwenhoek find when he looked into lake water How did he describe it?
    8 years ago
  • gorbulas underhill
    How leeuwenhoek microscope works?
    8 years ago
  • angelica
    What organizations have biomedical illustration companies?
    5 years ago

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