Introduction to Pathology

Study Notes

Pathology studies the structural, biochemical, and functional changes in cells, tissues, and organs that cause disease.
Divided into two main specialties: Anatomic Pathology and Clinical Pathology.

Anatomic Pathology: Involves autopsies, surgical pathology, and cytology.
Clinical Pathology: Involves hematology, chemistry, microbiology, and blood bank services.

Etiology: Identifies the origin or cause of disease.
Pathogenesis: Describes the process from initial stimulus to the disease's ultimate expression.
Morphologic Changes: Focuses on structural alterations in cells or tissues.
Functional Derangements and Clinical Manifestations: Encompasses signs, symptoms, and injuries affecting cells, tissues, and organs.

Stated, “All diseases are the results of visible cell abnormalities,” highlighting the cellular basis of disease.

Key terms in cell response include "-plasia" and "-trophy," indicating changes in growth patterns.

Retrogressive Changes: Organs or tissues become smaller than normal.
- Developmental Defects:
  - Aplasia: Incomplete or defective development of a tissue or organ.
  - Agenesia: Complete absence of an organ.
  - Hypoplasia: Failure of an organ to reach its full size.
  - Atresia: Failure of an organ to form an opening.
Atrophy: Decreased size due to reduced cell size, number or both, caused by various factors like disuse, denervation, or nutritional deficits.

Organs or tissues grow larger (e.g., hyperplasia or hypertrophy).
Hyperplasia: Increase in tissue size via increased cell number can be physiological or pathological.
Hypertrophy: Increase in tissue size due to cell size growth, which can be physiological (e.g., muscle) or pathological.

A reversible change where one type of normal adult cell is transformed into another type (e.g., columnar to squamous in the respiratory tract).

Known as atypical hyperplasia; showcases abnormal growth characterized by variations in size, shape, and orientation of cells; considered pre-neoplastic.

Represents dedifferentiation; a significant regression to more primitive cell types and is irreversible.

Refers to tumors and the continuous, uncontrolled proliferation of abnormal cells, indicating pathologic overgrowth.

Reversible Change:
- Progresses from cell injury to swelling, associated with ATP depletion and reduced oxidative phosphorylation.
Irreversible Change:
- Leads to cell death due to mitochondrial dysfunction, membrane defects, and lysosomal digestion.

Common causes of cell injury include hypoxia, physical agent exposure, chemical toxicity, infection, immunologic reactions, genetic factors, and nutritional deficiencies.

Cells undergo adaptations like hyperplasia, hypertrophy, or atrophy in response to changes in demand or environment, reflecting resilience or vulnerabilities in cellular function.