Introduction to Pathology

Introduction to Pathology

• Pathology is the study of disease using scientific methods
• It examines changes in cells and tissues caused by injury
• Disease is defined as an abnormality in structure or function of any part of the body (physiological or psychological dysfunction)

Parts of Pathology

• There are five major aspects of pathology:
  • Epidemiology: studies the occurrence and distribution of diseases in populations, considering factors like sex, age, race, occupation, geographic location, and socioeconomic status.
  • Etiology: investigates the cause of a disease. If the cause is unknown, it's called idiopathic, cryptogenic, or essential.
  • Pathogenesis: explains the steps from the initial cause to tissue injury. This includes inflammatory, degenerative, carcinogenic, and immunological processes.
  • Morphologic changes: describes structural changes occurring in cells and tissues due to disease. These changes can be observed macroscopically (naked eye) or microscopically (microscope).
  • Clinical features (functional alteration): investigates the signs and symptoms of a disease. Symptoms are subjective (what the patient experiences), while signs are objective (what the doctor observes). Clinical features combined provide a comprehensive picture.

Epidemiology

• Epidemiology studies the distribution and determinants of diseases in populations
• Epidemiology analyzes patterns, causes, and effects of disease conditions across populations
• Factors impacting disease distribution in populations include:
  • Sex
  • Age
  • Race
  • Occupation
  • Geographic Location
  • Socioeconomic status
• Certain occupations and geographic locations increase the risk of specific diseases.

Other factors in epidemiology

• Geographic location: Specific diseases are more prominent in certain parts of the world
  • Example: Undereveloped countries often face high rates of malnutrition and infections like tuberculosis
  • Example: Developed countries often have higher incidences of cardiac problems and obesity-related issues
• Socioeconomic factors The social and financial status of those affected by a specific disease

Key concepts

• Prevalence: Total number of cases of a particular disease within a certain population during a specific time period.
• Incidence: Number of new cases of a particular disease within a certain population during a specific time period. Immunization programs impact incidence.
• Sequelae: Complications or consequences that result from a disease.
• Prognosis: Expected outcome of a disease based on its severity. A well prognosis indicates improvement; a poor prognosis indicates worsening, possibly leading to death.
• Morbidity: Presence of an illness.
• Mortality rate: Number of deaths in a particular population during a specific time period. Often high in diseases with poor prognoses.

Etiology & Classification of Disease

• Etiology in pathology is the study of the cause of a disease
• Diseases can be classified based on their cause (etiology) and pathogenic mechanisms

Types of Diseases

• Diseases can be categorized as congenital or acquired.

Pathogenesis

• Pathogenesis is the study of the steps leading to a disease's development and the manifestation of tissue injury
• There are four fundamental pathogenetic mechanisms: inflammatory, degenerative, carcinogenic, and immunologic processes
• Pathogenesis leads to observable changes in the structure of tissues.

Morphologic Changes

• Morphologic changes are structural alterations in cells or tissues due to disease
• These changes can be observed using macroscopic (naked eye) and microscopic (microscope) examination
• These findings help in diagnosis

Clinical Features

• Clinical features refer to the signs and symptoms associated with a disease.
• Symptoms are subjective experiences reported by the patient (e.g., pain, fatigue).
• Signs are objective observations made by a physician (e.g., swelling, enlarged organs).

Purposes of Epidemiology

• Investigating the extent of a disease in a community
• Studying natural disease patterns, histories, and prognoses
• Identifying disease causes and risk factors
• Guiding good health care based on findings
• Recommending and implementing preventative and treatment strategies
• Evaluating healthcare facilities and programs
• Providing information, and developing public health policies