Age-Related Anatomical Changes

Age-Related Anatomical Changes

Age-Related Anatomical Changes

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  • Hallmarks of Cellular Aging:
    • Telomere Shortening: Progressive loss of chromosomal ends, limiting cell divisions (replicative senescence).
    • Cellular Senescence: Irreversible cell cycle arrest; cells secrete Senescence-Associated Secretory Phenotype (SASP) factors, promoting inflammation.
    • Mitochondrial Dysfunction: Leads to ↓ATP production and ↑Reactive Oxygen Species (ROS), causing oxidative damage.
    • Epigenetic Alterations: Changes like DNA methylation & histone modification alter gene expression patterns.
    • Stem Cell Exhaustion: Diminished self-renewal and differentiation capacity, impairing tissue repair and regeneration.
  • General Physiological Decline:
    • Homeostenosis: Narrowed range of physiological parameters to maintain homeostasis, especially under stress.
    • Reduced Physiological Reserves: Decreased functional capacity across organ systems, increasing vulnerability.

Hallmarks of Cellular Aging Diagram

⭐ The Hayflick limit describes the finite number of times a normal human cell population will divide before cell division stops, typically around 40-60 divisions for human fetal fibroblasts.

  • Osteoporosis: Systemic skeletal disease with ↓ bone mineral density (BMD) & microarchitectural deterioration.
    • Diagnosis: T-score ≤ -2.5.
    • 📌 Risk Factors (ACCESS): Alcohol, Corticosteroid, Calcium low, Estrogen low, Smoking, Sedentary lifestyle.
  • Sarcopenia: Progressive, generalized loss of skeletal muscle mass, strength, & function.
    • Diagnosis: ↓ muscle mass + (↓ muscle strength OR ↓ physical performance).
  • Osteoarthritis: Degenerative joint disease.
    • Features: Cartilage degradation, osteophytes (bone spurs), joint space narrowing, subchondral sclerosis. Bone Density Changes in Aging Knees

⭐ Vertebral compression fractures are the most common osteoporotic fractures.

Cardiovascular System:

  • Arteries: ↑ stiffness, ↑ pulse wave velocity.
    • ↑ Systolic BP (SBP).

    ⭐ Isolated systolic hypertension (SBP ≥140 mmHg, DBP <90 mmHg) is the most common form in elderly.

  • Heart:
    • Left Ventricular Hypertrophy (LVH).
    • Diastolic dysfunction (impaired LV filling).
    • Valvular calcification (e.g., aortic stenosis).
    • ↓ Baroreceptor sensitivity (risk of postural hypotension).
    • ↓ SA node pacemaker cells.

Respiratory System:

  • Mechanics:
    • ↓ Lung elasticity.
    • ↑ Chest wall stiffness.
  • Lung Volumes:
    • ↓ FEV1, ↓ FVC.
    • ↑ Residual Volume (RV), ↑ Functional Residual Capacity (FRC).
    • Total Lung Capacity (TLC) often unchanged.
  • Gas Exchange:
    • ↑ Ventilation/Perfusion (V/Q) mismatch.
    • ↓ Diffusing capacity ($D_LCO$).

Age-related heart and lung changes

Nervous System ("Brain Fades"):

  • Structural Changes:
    • Mild cortical atrophy.
    • Ventricular enlargement (often compensatory).
  • White Matter: Changes evident as leukoaraiosis.
  • Neurotransmitter Levels:
    • ↓ Dopamine (impacting motor control, cognition).
    • ↓ Acetylcholine (crucial for memory).
  • Cellular Pathology: Senile plaques and neurofibrillary tangles may be present even in non-demented elderly individuals. MRI comparison of young vs aged brain

Sensory System ("Sense Shades"):

  • 👁️ Presbyopia (Vision): Due to ↓ lens elasticity, leading to impaired near vision.
  • 👂 Presbycusis (Hearing): Progressive bilateral sensorineural hearing loss, particularly for high-frequency sounds.

    ⭐ Presbycusis typically affects high-frequency sounds first and is the most common cause of hearing loss in adults.

  • 👃👅 Olfaction & Gustation: General decline in the sensitivity of smell and taste.

High‑Yield Points - ⚡ Biggest Takeaways

  • Thymic involution begins early, with significant adipose replacement by adulthood.
  • Arterial stiffening (arteriosclerosis) from elastin degradation and collagen accumulation.
  • Brain atrophy involves neuronal loss, ventricular enlargement, and potential plaque/tangle formation.
  • Sarcopenia is the progressive loss of skeletal muscle mass and function.
  • Osteoporosis features reduced bone mineral density, increasing fracture susceptibility.
  • Presbyopia (age-related farsightedness) due to lens elasticity loss.
  • Skin aging includes dermal thinning, reduced elasticity, and impaired wound healing.

Practice Questions: Age-Related Anatomical Changes

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Regarding the peak expiratory flow rate, which of the following statements is false?

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Flashcards: Age-Related Anatomical Changes

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The infant has a _____ position of larynx compared to adults

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The infant has a _____ position of larynx compared to adults

higher

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