Cellular Adaptations: Hypertrophy, Hyperplasia, Atrophy, Metaplasia
Start with the big picture
Cellular adaptations differ in what changes: hypertrophy increases cell size, while hyperplasia increases cell number. Atrophy reduces cell size and number as protein degradation outweighs synthesis; its causes include reduced workload, denervation, ischemia, malnutrition, endocrine loss, and aging. Metaplasia replaces one differentiated cell type with another through stem-cell reprogramming, often in response to persistent irritation. Examples include airway changes associated with smoking and Barrett esophagus associated with chronic GERD. These changes can affect tissue function, and persistent metaplasia may predispose to dysplasia and carcinoma. Although adaptations are reversible, ongoing or severe stress can lead to irreversible cellular injury and death.
What you'll learn
- Distinguish hypertrophy, hyperplasia, atrophy, and metaplasia by their defining cellular changes.
- Explain how hypertrophy and hyperplasia arise and identify representative examples.
- Recognize common causes and a morphological hallmark of atrophy.
- Describe metaplasia as stem-cell reprogramming and identify its clinical implications.
- Relate the reversibility of adaptation to the progression of cellular injury.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
