ASPECTS OF AGING AND REHABILITATION OF OLDER ADULTS

PHYSIOLOGY OF AGING

Robert S. Stall, MD

Last updated December 27, 1995

  1. Changes in Body Composition--altered medication pharmacokinetics
    1. Increased fat (esp. centrally)
    2. Decreased muscle mass
    3. Decreased body water
  2. Skin changes--increased susceptibility to infection, trauma, and external environment
    1. Decreased vascularity and subcutaneous fat
    2. Decreased # sebaceous and sweat glands
    3. Increased pain threshold (i.e., pain less noticeable)
    4. Decreased sensory acuity
  3. The Senses--affect functional ability, apparent cognitive status, and nutritional status
    1. Decreased vision/hearing
    2. Decreased taste/smell/touch
  4. Immune Function--increased susceptibility to infection
    1. Decreased cell-mediated immunity
    2. Decrease antibody response to foreign antigens
    3. Increased autoantibodies
  5. Renal Function--decreased creatinine clearance despite "normal" creatinine (140-age/serum creatinine=approximate creatinine clearance)
    1. Decreased # functional nephrons
    2. Structural & functional changes (sclerosis of glomeruli and vasculature, basement membrane thickening, decreased levels of renin and aldosterone) cause impaired regulation of water and electrolytes
  6. GU--obstruction, incontinence & infection extremely common
    1. Decreased bladder capacity
    2. Prostatic hypertrophy
    3. Mucosal atrophy in women
  7. Liver--altered drug metabolism
    1. Atrophy
  8. Heart--impaired perfusion of all body tissues
    1. Calcification and sclerosis of fibrous cardiac skeleton-->predisposes to conduction abnormalities and valvular dysfunction
    2. Increased peripheral resistance-->cardiac hypertrophy
    3. Decreased diastolic filling rate, increased filling from atrial contraction-->end diastolic volume constant (but will be compromised in atrial fibrillation)
  9. Lungs--impaired oxygenation of all body tissues
    1. Decreased surface area of alveolar capillary membranes, increased alveolar size-->ventilation-perfusion mismatch, decreased PaO2
    2. Decreased respiratory muscle strength/mucociliary clearance-->predisposes to infection
    3. Decreased responsivity to hypoxia and hypercarbia-->breathing disorders and perioperative respiratory complications
  10. Reference
    1. Physiology of Aging--A Synopsis (Second Edition), Richard A. Kenney, Year Book Medical Publishers, 1989.

Comments and questions welcome (DRSTALL@ubvms.cc.buffalo.edu)!

This summary Copyright 1995 Robert S. Stall, MD--may be used freely with acknowledgment