Pathology

Pathology is the scientific study of disease processes that affect normal anatomy and physiology. Training in pathology requires a medical degree and roughly five years of postgraduate study. Anatomical and physiological changes are pathological changes when they result from an underlying disease process or abnormality.

Since ancient times, physicians have concerned themselves with the distinguishing features of health and disease. Until the early nineteenth century, however, their ideas were based on a theory of humors (that is, elemental fluids in the body), rather than systematic examination of body parts and disease processes. Disease was believed to result from an imbalance of these humors. Dissection of dead bodies to learn about disease was not allowed by religious leaders and obstructed progress in the study of anatomy and pathology through the Middle Ages (350–1450). By the Renaissance (from the fourteenth to sixteenth centuries), however, reports from post-mortem dissections began to provide a new and important source of information contributing to medical knowledge. In his Universa medicina, Jean François Fernel (1497–1558) introduced the term “pathology” to describe the abnormalities detected by anatomists when they dissected cadavers. However, Fernel still held to the ancient teachings of the humors.

In the eighteenth century, the anatomical basis of disease began to emerge. Public hospitals provided a seemingly endless supply of corpses for dissections after death, and hospitals became centers for teaching and practicing morbid anatomy (the abnormal structures in the body associated with disease). By the second half of the eighteenth century, in both the United States and Europe, surgeons and physicians had already begun to correlate signs and symptoms of patients with findings from autopsies after the patients died.

In 1761, Giovanni Battista Morgagni (1682–1771) published the first textbook to systematically detail morbid anatomy and to locate diseases within individual organs. However, humoral theories remained firmly entrenched, and the study of anatomy was still limited to what pathologists could observe of organs, muscles, and bones with the naked eye. All the same, as a result of their investigations into corpses, pathologists in many different countries were beginning to ask questions about what made a tumor benign or malignant, the nature of pus, how wounds heal, and whether blood clots are beneficial or harmful.

Major progress was quick to follow. In France, Marie Francçois Xavier Bichat (1771–1802) studied tissues rather than organs. One of his important contributions was the announcement that the disease of a tissue is the same no matter which organ the tissue is in. Bichat worked without the aid of a microscope. However, the introduction of improved compound microscopes in the 1820s made it possible to study both normal and diseased tissue more extensively and more accurately than ever before. In 1858, Rudolf Carl Virchow (1821–1902) proved conclusively that diseases arose in the cells of organs and tissues, not in the organs and tissues generally. Not long after, the investigations of Louis Pasteur (1822–1895) and Robert Koch (1843–1910) into bacteria were a major step in rounding out understanding of how disease works.

By the end of the nineteenth century, pathology had come into its own as a separate medical specialty. In the twenty-first century, pathologists perform, evaluate, or supervise diagnostic tests, using materials from living or dead patients. Their work is carried out primarily in the laboratory, and they work closely with physicians who are directly in charge of patients. Among the materials a pathologist examines (in procedures generally known as biopsies) are surgically removed body parts, blood and other body fluids, urine, feces, and so on. Pathologists also practice autopsy, which allows them to reconstruct the end of the physical life of a dead person by providing information about the workings of disease they would not be able to get any other way. It is not possible for any one person to know all there is to know about pathology, so pathologists who specialize in one area or another frequently work together. For example, pediatric pathology studies disease processes in children. Forensic pathology is a subspecialty whose goal is to clarify crimes or legal issues.

Advances in laboratory techniques and increasingly fine-scaled instrumentation have greatly expanded the information available to the pathologist in determining the causes of disease. Research in genetics is also changing the study of pathology. More and more, pathologists are being called on to examine the molecular structure of deoxyribonucleic acid (DNA) and to identify molecular markers of disease, as well as to study the impact of environmental factors on heredity.

Pathologists play an increasingly important role in diagnosis, research, and in the development of clinical treatments for disease. A specialized branch of pathology, forensic pathology, offers a vast array of molecular diagnostic techniques (including DNA fingerprint analysis) toward identification of remains, gathering of evidence, and identification of suspects.

Research in pathology often focuses on identifying processes of abnormal cell growth, the causes of general morphologic changes, and the extent or effects of necrosis, infection, inflammation and other processes associated with disease or injury. Pathologists often work with public health professionals to collect data essential to understanding the prevalence and etiology (origin or cause) of specific diseases.

Modern pathology laboratories rely heavily on molecular biology techniques and advances in biotechnology. During the last two decades, there have been tremendous advances in linking changes in cellular or tissue morphology (i.e., gross appearance) with genetic and/or intracellular changes. In many cases, specific molecular tests can definitively identify disease process, and of critical importance to the treatment of disease, and make a correct diagnosis at an earlier stage in the disease process.

Pathologists attempt to relate observable changes to disease process. Whether the changes are evident morphologically—or are distinguishable only via sophisticated molecular tests—the goal is to determine the existence and/or etiology of disease (the cause of disease). Once the etiologic agents are identified, the general goal of research is to document and gather evidence of the pathogenesis of disease (i.e., the mechanisms by which etiologic agents cause disease).

On a daily basis, pathologists perform a broad spectrum of tests on clinical samples to determine anatomical and physiological changes associated with a number of disease processes, including the detection of cancerous cells and tumors.

Major branches of pathology include the study of anatomic, cellular, and molecular pathology. Specific clinical studies often focus on transplantation pathology, neuropathology, immunopathology, virology, parasitology, and a number of clinical subspecialties (e.g., pediatric pathology).

See also Aging and death; Forensic science.

Pathologist

Plant pathologists are scientists who work with plant diseases. Trained primarily as biologists, they have expertise both in plant science and microbiology. Whereas in medicine the pathologist is a specialist who analyzes diseased tissues, the plant pathologist is concerned with all aspects of plant disease. All plants are subject to disease, and the work of plant pathologists is central to the management of diseases.

Many plant pathologists may be compared to the general practitioner in medicine, but there are many areas of specialization that may involve the kind of crop or pathogen. Most plant pathologists who work with field crops or vegetables have rather general training in plant pathology, but virologists and nematologists require specialized training because these agents are very different from all other pathogens. Forest pathologists also need unique training, both because the forest is a very different crop and because the common pathogens are different from those that attack agricultural crops. Some plant pathologists are biochemists or molecular biologists who study diseased plants or pathogens. Epidemiologists study the spread of disease in populations and they must be well grounded in mathematics and statistics.

Most jobs taken by plant pathologists require a doctorate degree, but some directors of diagnostic labs have a master's degree. Plant pathologists must be well versed in plant physiology and genetics and must have knowledge of all disease-causing agents. The study of the fungi is particularly important since these are the most numerous and troublesome pathogens of plants. Courses in plant pathology provide background in disease initiation and progress for each kind of pathogen. This knowledge is used when designing programs for management of disease.

Plant pathologists are employed by universities, federal and state governments, and a wide range of industries. All land-grant universities have plant pathologists who are responsible for resident instruction, research, and extension education. Plant pathologists conduct research at state agricultural experiment stations and the U.S. Department of Agriculture, and are employed by federal and state agencies that enforce regulations regarding pesticide use and food safety. Chemical companies employ plant pathologists for production of more effective and safer pesticides, and seed companies use their expertise to produce disease resistant varieties. Many plant pathologists work as consultants or provide service in diagnostic labs.

The complexity of two interacting living systems—the plant and the pathogen—makes plant pathology a very challenging field. An appealing feature of employment as a plant pathologist is the opportunity for work in a wide range of environments. Teaching may occur on the farm as well as in the classroom, and research may be conducted in the field or greenhouse as well as in the laboratory. Disease specimens may be diagnosed in the lab, but disease progress must be evaluated in the field. Plant pathologists have opportunities for research in international centers and for cooperative work with plant pathologists in other countries.

Work by the plant pathologist touches on many important contemporary issues, such as overpopulation, the safety of genetically engineered food, and the effects of pesticides on human health and the environment. But the role played by plant pathologists in the production of abundant, safe food for people of the world is of central importance.

see also Pathogens.

Ira W. Deep

Bibliography

The American Phytopathological Society. [Online] Available at http://www.apsnet.org/.

Pathology

Pathology is the scientific study of disease processes that affect normal anatomy and physiology . Anatomical and physiological changes are pathological changes when they result from an underlying disease process or abnormality. Forensic science is geared towards deducing the nature of the physical and chemical insults that have been inflicted on one or more persons. Sometimes these insults can cause changes in the body. When that occurs, the forensic examination overlaps with pathology. Forensic pathology is the study of the anatomical or physiological changes that are suspicious in their origin.

Pathologists play an increasingly important role in diagnosis, research, and in the development of clinical treatments for disease. A specialized branch of pathology, forensic pathology, offers a vast array of molecular diagnostic techniques (including DNA fingerprint analysis) toward identification of remains, gathering of evidence , and identification of suspects.

Modern pathology labs rely heavily on molecular biology techniques and advances in biotechnology. During the last two decades, there have been tremendous advances in linking changes in cellular or tissue morphology (i.e., gross appearance) with genetic and/or intracellular changes. In many cases, specific molecular tests can definitively identify disease processes and help make a correct diagnosis at an earlier stage in the disease process.

Pathologists attempt to relate observable changes to disease process. Whether the changes are evident morphologically (structurally) or are distinguishable only via sophisticated molecular tests, the goal is to determine the existence and/or etiology of disease (the cause of disease). Once the etiologic agents are identified, the general goal of research is to document and gather evidence of the pathogenesis of disease (i.e., the mechanisms by which etiologic agents cause disease).

On a daily basis, pathologists perform a broad spectrum of tests on clinical samples to determine anatomical and physiological changes associated with a number of disease processes, including the detection of cancerous cells and tumors.

Major branches of pathology include the study of anatomic, cellular, and molecular pathology. Specific clinical studies often focus on transplantation pathology, neuropathology, immunopathology, virology, parasitology , and a number of clinical subspecialties (e.g., pediatric pathology).

Forensic pathology has several specific aims in addition to the aforementioned. The pathological examinations seek to establish what weapon was used, if that is relevant. Also, whether a death was self-inflicted or was a murder is another goal. Finally, the contribution to the death of a pre-existing disease or condition is a goal. For example, a person who is infected with the Human Immunodeficiency Virus often has a compromised immune system that lays them open to the development of other maladies that might otherwise not be fatal (i.e., fungal infections).

see also Amphetamines; Barbiturates; Botulinum toxin; Death, mechanism of; Electrical injury and death; Food poisoning; Hemorrhagic fevers and diseases; Pathogens; Toxicological analysis.

Pathology

Pathology is the scientific study of disease processes that affect normal anatomy and physiology . Anatomical and physiological changes are pathological changes when they result from an underlying disease process or abnormality.

Pathologists play an increasingly important role in diagnosis , research, and in the development of clinical treatments for disease. A specialized branch of pathology, forensic pathology, offers a vast array of molecular diagnostic techniques (including DNA fingerprint analysis) toward identification of remains, gathering of evidence, and identification of suspects.

Research in pathology often focuses on identifying processes of abnormal cell growth, the causes of general morphologic changes, and the extent or effects of necrosis, infection , inflammation and other processes associated with disease or injury. Pathologists often work with public health professionals to collect data essential to understanding the prevalence and etiology (origin or cause) of specific diseases.

Modern pathology labs rely heavily on molecular biology techniques and advances in biotechnology . During the last two decades, there have been tremendous advances in linking changes in cellular or tissue morphology (i.e., gross appearance) with genetic and/or intracellular changes. In many cases, specific molecular tests can definitively identify disease process, and of critical importance to the treatment of disease, and make a correct diagnosis at an earlier stage in the disease process.

Pathologists attempt to relate observable changes to disease process. Whether the changes are evident morphologically—or are distinguishable only via sophisticated molecular tests—the goal is to determine the existence and/or etiology of disease (the cause of disease). Once the etiologic agents are identified, the general goal of research is to document and gather evidence of the pathogenesis of disease (i.e., the mechanisms by which etiologic agents cause disease).

On a daily basis, pathologists perform a broad spectrum of tests on clinical samples to determine anatomical and physiological changes associated with a number of disease processes, including the detection of cancerous cells and tumors.

Major branches of pathology include the study of anatomic, cellular, and molecular pathology. Specific clinical studies often focus on transplantation pathology, neuropathology, immunopathology, virology, parasitology, and a number of clinical subspecialties (e.g. pediatric pathology).

See also Aging and death; Forensic science.

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pa·thol·o·gy / pəˈ[unvoicedth]äləjē/ • n. the science of the causes and effects of diseases, esp. the branch of medicine that deals with the laboratory examination of samples of body tissue for diagnostic or forensic purposes. ∎ Med. pathological features considered collectively; the typical behavior of a disease: the pathology of Huntington's disease. ∎ Med. a pathological condition: the dominant pathology is multiple sclerosis. ∎  mental, social, or linguistic abnormality or malfunction: the city's inability to cope with the pathology of a burgeoning underclass. DERIVATIVES: pa·thol·o·gist / -jist/ n.

pathology Strictly speaking, the scientific study of organic diseases, their causes and symptoms (hence, ‘pathologist’). However, pathological suggests morbidity and abnormality, so the term has also been extended to certain branches of psychiatry and criminology, most obviously in the widespread use of the term ‘psychopath’. In sociology, pathology was once held to be analogous to deviance and social problems or ‘social disease’ (notably in the work of Émile Durkheim), and the concept also blurs into the associated notion of social pathology (see, for example, E. Lemert , Social Pathology, 1951, and B. Wootton , Social Science and Social Pathology, 1959
).

pathology, study of the cause of disease and the modifications in cellular function and changes in cellular structure produced in any cell, organ, or part of the body by disease. The changes in tissue include degeneration, atrophy, hypertrophy, hyperplasia, and inflammation. The microscope is an important factor in detecting tissue changes, especially in the examination of small sections of tissue removed for diagnosis (biopsy); for this reason real progress in pathology was not made until the 19th cent. Other diagnostic techniques for testing body fluids and tissues for abnormal composition or metabolisms are electronmicroscopy, immunocytochemistry, and molecular pathologies.

See E. R. Long, A History of Pathology (1962, repr. 1965); W. A. Anderson and T. M. Scotti, Synopsis of Pathology (8th ed. 1972); L. V. Crowley, Introductory Concepts in Pathology (1972); L. Crowley, Introduction to Human Disease (1989).

Pathology ★★ 2008 (R)

Grisly, perverse horror thriller finds amoral young doctor Ted Grey (Ventimiglia) beginning his residency in pathology. His fellow docs are a sex-and-drugs crazed bunch led by loony Jack (Weston). Jack has devised a game in which one of the team commits a murder and then the others perform an autopsy to decide how it was done (so much for the Hippocratic Oath). Ted's soon involved up to his scalpel but discovers getting out of Jack's band of merry killers isn't so easy. 93m/C DVD . US Milo Ventimiglia, Michael Weston, Alyssa Milano, Lauren Lee Smith, Johnny Whitworth, John de Lancie, Mei Melancon, Keir O'Donnell; D: Marc Schoelermann; C: Ekkehart Pollack; M: Johannes Kobilke, Robert Williamson.