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Difficulty: EasyCellular Injury and Adaptation

Match each clinical presentation to the underlying cellular adaptation mechanism it best represents.

  • Echocardiography of a man with poorly controlled essential hypertension reveals a thickened left ventricular wall.Hypertrophy
  • Biopsy of the distal esophagus in a patient with chronic reflux demonstrates replacement of native squamous epithelium with intestinal-type columnar epithelium.Metaplasia
  • Histologic evaluation of the prostate in a man with urinary hesitancy shows an increased number of normal-appearing glandular structures and fibromuscular stroma.Hyperplasia
  • Examination of a woman six weeks after a radius fracture reveals significantly reduced girth of the affected forearm immediately following cast removal.Atrophy

Answer

The left ventricular thickening matches Hypertrophy. The esophageal epithelial change matches Metaplasia. The increased prostatic glandular structures match Hyperplasia. The reduced forearm girth matches Atrophy.
Each clinical vignette highlights a classic, fundamental mechanism by which cells adapt to environmental stressors, altered demand, or hormonal signals. Hypertrophy involves cell enlargement, metaplasia involves cell type switching, hyperplasia involves cell proliferation, and atrophy involves cell shrinkage.

Step-by-Step Solution

1
Analyze the cardiac presentation.
The myocardial cells have enlarged in response to increased afterload from hypertension.
Cardiac myocytes cannot undergo significant division; they adapt to mechanical stress solely by increasing in size (hypertrophy).
2
Analyze the esophageal presentation.
One mature epithelial type has been replaced by another type better suited to handle the acidic environment.
This reprogramming of stem cells to substitute the native tissue type with a more resilient one is the hallmark of metaplasia.
3
Analyze the prostatic presentation.
There is an absolute increase in the count of epithelial and stromal cells.
Hormonal stimulation (e.g., via dihydrotestosterone) triggers cellular proliferation, leading to hyperplasia.
4
Analyze the musculoskeletal presentation.
The skeletal muscle mass has decreased significantly due to lack of use.
Immobilization reduces the functional demand on the muscle, causing cells to degrade their own structural proteins and shrink, which is atrophy.

Key Concept

Cellular Adaptation
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Topics

Cellular Injury and Adaptation

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