Physiologic hyperplasia and hypertrophy are not mutually exclusive processes. Both mechanisms often occur simultaneously in response to functional demand.
Option 3 is FALSE because uterine enlargement in pregnancy involves both hyperplasia AND hypertrophy:
This is a classic example of combined hyperplasia and hypertrophy, not hyperplasia alone.
| Adaptation | Mechanism | Example |
|---|---|---|
| Cardiac hypertrophy | Mechanical stretch → activation of MAPK, PI3K/Akt pathways → increased protein synthesis | Systemic hypertension, aortic stenosis |
| Hepatocyte hyperplasia | HGF, TGF-α, IL-6 → increased cyclin-dependent kinase activity → S-phase entry | Post-hepatectomy regeneration |
| Renal compensatory hypertrophy | Loss of nephrons → increased glomerular filtration pressure → growth factor activation (IGF-1, FGF) | Unilateral nephrectomy |
Hyperplasia = increase in cell number (mitosis required) Hypertrophy = increase in cell size (protein synthesis, organelle proliferation)
Most physiologic adaptations involve both processes to varying degrees.
Uterine enlargement in pregnancy increases from 50 g to 900 g — this massive growth is achieved through:
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