Pathology

Introduction

In this section, you'll be introduced to pathology. You'll review the history of pathology and different specialties within the science of pathology.

 

What is Pathology?

Pathology is the study of disease and injury and how they affect the body. The study of pathology helps to form a bridge between basic science and the clinical practice of taking care of patients. Pathology, more specifically, is the branch of medicine that specializes in studying how disease affects the body at both the microscopic and macroscopic, or gross, levels. The term macroscopic refers to something that's visible to the naked eye. Microscopic, on the other hand, refers to something that's so small that it can't be seen without the use of a microscope.

A pathologist is a doctor who specializes in the study of disease and injury and how it affects the body. A pathologist examines cells and tissues using a tool called a microscope. There are three main studies within the science of pathology:

1. Anatomic pathology focuses on the gross and microscopic changes in the tissues caused by disease and injury.

2. Clinical pathology is the laboratory study and analysis of bodily fluids and waste products such as blood, urine, and sputum.

3. Forensic pathology is a combination of both anatomic and clinical pathology that focuses on issues in civil and criminal law.

 

Within each of these main studies are specializations that further focus on specific areas within pathology.

A medical technologist is an allied health professional who performs much of the day-to-day clinical pathology testing in the clinical lab setting.

When we talk about pathology, we must think about what constitutes health and what constitutes disease. Health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. So, health incorporates all aspects of a human being, not just the physical well-being. On the other hand, disease is an abnormal alteration of a structure or function in the body.

Some other terms that are commonly used in pathology with which you should be familiar are listed here:

• Epidemiology. The study of when and where disease occurs.
• Etiology. The study of the cause of disease within the population.
• Exacerbation. Sudden increase in the severity of disease. Usually, there's an increase in the signs and symptoms during the exacerbation.
• Illness. The reaction of the patient to the disease in the form of symptoms.
• Lesion. A visible characteristic change in tissues and cells, usually localized to one specific area on or in the body. They may be benign or cancerous.
• Morphology. The study of the structural changes at the cellular and tissue level.
• Pathogenesis. The development of a disease.
• Patient. The person affected by the disease.
• Physical signs. Functional implications from the disease that are felt by the patient.
• Remission. A period of decreased disease activity; less intense for a period of time. This may be temporary.
• Sequelae. The late-term effects, or aftereffects, produced by the disease.

 

History of Pathology

Pathology is a science that has been developing and progressing since ancient times. In ancient times, people believed that disease was caused by a "curse" or the "evil eye" of the spirits. As time progressed, scientists discovered the real reasons behind illness. Following are some of the major contributors to the science of pathology:

• In 1665, Robert Hooke discovered the cell, the basic structural, functional, and biological unit of living organisms.
• In 1839, Theodor Schwann developed the cell theory, the concept that all living organisms are composed of one or more cells, and that all cells come from preexisting cells. Cell theory also states that vital functions of an organism occur at the cellular level and that the genetic information necessary for regulating cell function was copied and pasted on to the daughter cells during reproduction.
• In the late 1600s, Antony Van Leeuwenhoek worked on developing lenses and magnification. His work on the microscope contributed significantly to the discovery and study of single-celled organisms.
• During the 1800s, Louis Pasteur worked as a scientist and researcher in the university setting. He's known for developing the process of pasteurization, in which a substance is heated to a specified temperature and for a specified time to kill microbes. Pasteurization has helped reduce the spread of foodborne illness. Milk is a common pasteurized product. Pasteur also discovered the principle of vaccination.

 

The main objective of pathology is to understand the nature of disease by focusing on the following ideas:

• Identifying the etiology
• Understanding the pathogenesis
• Understanding the pathological changes
• Identifying the clinical features, including the functional and structural changes (this would also include the patient's signs and symptoms)
• Preventing complications
• Developing a prognosis

Histopathology. The study of diseases in the tissues, at either the gross/macroscopic or microscopic level. Histopathology is often associated with surgery, as samples are analyzed to determine the extent of disease. There's also a forensic science subspecialty.

Cytopathology. The study of disease at the cellular level. A Pap smear is a good example of the type of cell samples that are studied and evaluated.

Hematology. A branch of medicine specializing in blood disorders. A hematologist would treat patients with sickle-cell anemia, for example.

Microbiology. The study of microbes and single-celled organisms.

Immunology. A branch of medicine specializing in conditions of the lymphatic and immune system.

Geographic Pathology. A specialty that focuses on the study of diseases in populations in different parts of the world.

Medical Genetics. The study of the relationship between heredity and disease.

Molecular Pathology. Molecular pathology focuses on the detection and diagnosis of disease at the DNA level.

 

Key Points

• A pathologist is a doctor who specializes in the study of disease and injury and how it affects the body.
• There are three main studies within the science of pathology: anatomic, clinical, and forensic.
• Louis Pasteur worked as a scientist and researcher in the 1800s and developed the process of pasteurization. In pasteurization, a substance is heated to a specified temperature and duration to kill microbes.
• Specialties within the science of pathology include histopathology, cytopathology, hematology, microbiology, immunology, geographic pathology, medical genetics, and molecular pathology.