Cellular Adaptations - Comprehensive Student-Friendly Notes

Adaptations of Cellular Growth and Differentiation
1. Definition of Adaptations
 Cellular adaptations are reversible changes in cell size, number, phenotype,
metabolic activity, or function due to changes in the environment.
 They are mechanisms by which cells adapt to increased stress and maintain
homeostasis.
2. Types of Cellular Adaptations
A. Hypertrophy
 Definition: Increase in cell size, leading to an increase in the size of the
organ.
 Causes:
o Increased functional demand (e.g., hypertrophy of skeletal muscle
in athletes).
o Hormonal stimulation (e.g., uterine enlargement during pregnancy).
 Examples:
o Physiologic: Muscle hypertrophy due to exercise.
o Pathologic: Left ventricular hypertrophy due to hypertension.
B. Hyperplasia
 Definition: Increase in the number of cells, resulting in increased organ or
tissue size.
 Types:
 Physiologic Hyperplasia:
 Hormonal: Proliferation of the glandular epithelium of the breast
during pregnancy.
 Compensatory: Liver regeneration after partial hepatectomy.
 Pathologic Hyperplasia:
 Endometrial hyperplasia due to excessive estrogen stimulation.
 Benign prostatic hyperplasia (BPH) in elderly men.