Pathology Basics - Study of Disease

Pathology - Study of Disease

• Pathology is the study of disease (logos of pathos).
• Etiology involves causes, modifying factors, and genetic/environmental predisposition.
• Pathogenesis describes the steps in the development of a disease.
• Pathologists identify gross morphological changes in cells, tissues, and bodily fluids.

Introduction to Pathology

• Pathology is the study of disease.

Classification of Disease

• Disease classifications are crucial for statistical analysis of morbidity and mortality.
• Topographic classification categorizes disease by body region or system.
• Anatomic classification classifies based on specific organs or tissues affected.
• Physiological classification is based on functional derangement.
• Pathological classification focuses on the disease process itself. (e.g., neoplastic and inflammatory).
• Etiological classification categorizes by cause.
• Epidemiological classification examines the incidence and distribution in a population, and control of disorders.

Topographic Classification

• Diseases are categorized into groups like gastrointestinal, vascular, abdominal, and chest.
• Medical specialties often follow topographic divisions, e.g. vascular surgeons.

Anatomic Classification

• Disease is categorized by the affected organ or tissue, leading to specializations like cardiology.
• Anatomic classification helps identify different types of disease affecting a specific organ.

Physiological Classification

• This classification is based on the underlying functional derangement produced by a specific disorder.
• Examples of physiological classifications include respiratory and metabolic diseases.
• Respiratory diseases affect the intake/expulsion of air and the exchange of gases.
• Metabolic diseases involve disturbances in the body's chemical processes. (e.g., diabetes and gout).

Pathological Classification

• This approach focuses on the nature of the disease process, such as neoplastic or inflammatory diseases.
• Neoplastic diseases include various tumors, particularly cancers. (effect on human beings included).

Etiologic Classification

• Etiologic classification focuses on the cause/origin of a disease.
• Examples such as staphylococcal, rickettsial, or fungal diseases, including their specific effects.
• This classification outlines the effects of various biotic disease types.
• Examples include sexually transmitted diseases like syphilis and gonorrhea.

Epidemiological Classification

• This classification focuses on the incidence, distribution, and control of diseases in populations.
• It is crucial to understand the cause of observed diseases, for example: in typhoid diagnosis and distribution.
• Key factors to consider include the number of cases, time period of occurrence, and geographic distribution.

Cellular Responses

• Cells are actively involved in various processes, altering their structure and function continuously.
• Cells maintain homeostasis (steady state) under normal conditions.
• Cells adapt to physiologic and pathologic stress.

Cellular Response Stages

• Adaptive processes-
• Types of Adaptation: physiologic and pathologic.
• Types of cellular adaptive mechanisms: hypertrophy, hyperplasia, atrophy, and metaplasia.

Cellular Injury

• Cells respond to stress or injury and can have reversible or irreversible cellular damage.
• Reversible injury is characterized by mild and transient responses.
• Irreversible injury can lead to cellular death.
• Cellular death can be through necrosis or apoptosis.

Hypertrophy

• An increase in the size of cells, causing the organ size to increase.
• Physiological hypertrophy: estrogen and smooth muscle hypertrophy in pregnancy.
• Pathological hypertrophy: cardiac muscle enlargement (mechanical or trophic trigger).

Hyperplasia

• An increase in the number of cells.
• Physiological hyperplasia: hormonal proliferation, e.g. female breast during puberty.
• Pathological hyperplasia: excessive hormonal stimulation, e.g. uterine endometrial hyperplasia.

Atrophy

• Reduction in the size of cells by loss of cell substance.
• Causes: loss of innervation, diminished blood supply(ischemia), decreased protein synthesis, and aging.

Metaplasia

• Reversible change where one adult cell type is replaced by another.
• This change is often driven through reprogramming of stem cells or a phenotypic change of differentiated cells.
• Examples include squamous metaplasia in smokers which has a disadvantage of mucus and ciliary clearance loss, and a predisposition to lung cancer.
• Barrett's esophagus is another example.

Hypertrophy and Hyperplasia Summary

• Hypertrophy involves increased cellular size (and organ size).
• Hyperplasia involves an increased cell count.

This quiz delves into the fundamentals of pathology, exploring the study of disease, its classifications, and the roles of pathologists. Topics include etiology, pathogenesis, and various classification systems that are essential for understanding disease impact on health. Test your knowledge on the key concepts of this vital medical field.