Week 2: Normal Aging Physiology and Geriatric Syndromes

Determinants of Physical Aging

Physical condition in late life is driven by lifestyle choices (exercise, nutrition, stress management), genetics, and environmental exposure.

Cellular Aging Dynamics

Older cells visually resemble young cells under microscopic evaluation but have diminished physiological reserve and reduced capacity to withstand acute stressors.

Cardiovascular System Aging Changes

• Cardiac Alterations: Heart tissue thickens and stiffens; SA node pacemaker cells decrease while fatty/fibrous deposits increase, lowering baseline heart rate (bradycardia).

  • Left ventricular wall thickens, reducing chamber compliance and stroke volume. Tolerance for acute workloads decreases; orthostatic hypotension is common due to sluggish vascular reflexes.

• Vascular Alterations: Arteries and the aorta stiffen due to collagen cross-linking, increasing systemic vascular resistance and Systolic Blood Pressure (SBP) while Diastolic Blood Pressure (DBP) drops. Arterial baroreceptors lose sensitivity.

Hematologic System Aging Changes

Reduced total body water decreases total circulating blood volume.

Non-pathologic mild reductions in RBCs and H&H occur.

Immunologic System Aging Changes

Lymphocyte counts and antibody synthesis decline.

Nonspecific innate defenses weaken, while autoimmune reactivity increases (e.g., positive RF, ANA).

Infections present with increased severity, prolonged recovery, and atypical symptoms (e.g., confusion or tachycardia instead of high fever).

Respiratory System Aging Changes

• Airway & Reflexes: Ciliary clearance drops and laryngeal nerve ending density decreases, blunting the cough reflex and raising aspiration pneumonia risk.

• Alveolar & Parenchymal Changes: Functional alveoli decrease ("senile hyperinflation") and capillary membranes thicken, reducing total surface area available for gas exchange (O2–CO2).

• Chest Wall Dynamics: Chest wall stiffness increases (calcified costal cartilages) and respiratory muscle strength declines.

Renal System Aging Changes

Renal blood flow drops from 600 mL/min at age 40 to 300 mL/min by age 80. GFR and kidney size decrease by 20–30%. Baseline homeostasis is maintained unless challenged by acute stress or dehydration.

Urinary System Aging Changes

Loss of smooth muscle tone in the bladder and urethra causes urinary retention. Maximum bladder capacity drops from 500–600 mL to 250 mL, increasing frequency and shortening the warning latency period before voiding.

Musculoskeletal System Aging Changes

• Sarcopenia: Generalized, progressive loss of skeletal muscle mass, strength, and density. Accelerates physical fatigue, increases fall risks, reduces respiratory efficiency, and contributes to constipation. Best prevented by daily ambulation.

• Bone & Joint Changes: Bone resorption exceeds formation starting in the 30s. Water loss in intervertebral discs causes height loss; fluid loss in tendons and ligaments increases joint stiffness.

GI and Hepatic System Aging Changes

• Sensory & Secretory: Taste acuity decreases (salty/sweet perception drops, shifting preference to sweet foods). Reduced gastric HCl secretion impairs vitamin B12 and non-heme iron absorption. Enzyme reductions decrease calcium and folate absorption.

• Motility & Hepatic Clearance: Decreased peristalsis and gastrointestinal tone delay gastric emptying and slow colonic transit, causing constipation. Liver mass and cytochrome P450 drug clearance capacity decrease.

Neuro and Sensory System Aging Changes

• Central Nervous System: Synaptic transmission slows, prolonging reaction time. Sleep latency increases, total nocturnal sleep decreases, and daytime napping frequency rises.

• Ophthalmic Changes: Presbyopia (loss of near-vision accommodation due to lens hardening), xerophthalmia (dry eyes), and Arcus senilis (lipid ring along corneal margin) occur. Risk for cataracts, macular degeneration, and glaucoma increases.

• Auditory & Vestibular: Presbycusis (sensorineural hearing loss of high frequencies and sibilant consonants). Cerumen impaction causes conductive loss. Degeneration of vestibular cilia causes vertigo and gait instability.

Integumentary, Hair, and Nail Aging Changes

• Skin Alterations: Epidermal cell turnover slows by 10% per decade, delaying wound repair. Dermal thinning, collagen loss, and reduced subcutaneous fat cause skin sagging and wrinkles. Reduced sweat/sebaceous gland output leads to xerosis (dry skin).

• Hair & Nails: Men display temporal hair recession and ear/nasal hair growth; women display frontal hairline recession and facial hair growth. Toenails thicken, yellow, and grow slowly.

Endocrine and Reproductive System Aging Changes

• Female Reproductive System: Menopause (mean age 51) results from ovarian failure, ending estrogen/progesterone secretion and raising FSH/LH. Estrogen deprivation causes vaginal mucosal atrophy, dryness, and vasomotor symptoms lasting ≈5years.

• Male Reproductive System: Testosterone and testicular volume decline; BPH develops in most aging males, compressing the prostatic urethra and impairing urinary outflow.

Core Geriatric Syndrome

Delirium, Incontinence, Falls, Functional decline, Pressure ulcers.

Clinical Frailty Syndrome

Biological state of high vulnerability, sarcopenia, fatigue, slow gait, and weight loss. Pre-frail meets 1–2 criteria; frail meets 3–5+ criteria.

Cognitive Assessment/The 3 D’s

• Delirium: Acute, fluctuating, reversible confusional state secondary to underlying medical triggers.

• Dementia: Chronic, progressive, irreversible cognitive decline impacting functional ADLs.

• Depression: Mood disorder marked by anhedonia and cognitive slowing; treatable and reversible.

Nursing Interventions

• Communication: Lower voice pitch, eliminate background noise, stand directly in front of the patient, and avoid "ElderSpeak" (patronizing or infantilizing speech).

• Infection Prevention: Rigorous daily oral care prevents aspiration pneumonia from oral pathogens.

• Assessment Framework: Use the Fulmer SPICES tool (Sleep, Problems with eating, Incontinence, Confusion, Evidence of falls, Skin breakdown).