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HCR240-Chapter45PathophysiologicalConceptsofAging.pptx

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Chapter 45

Pathophysiologic Concepts of Aging

Overview

Percentage of U.S. population over the age of 65 years is growing

Three categories

Young-old: between 65 and 74 years

Middle-old: between 75 and 84 years

Old-old: older than age 85

Aging Concepts

Maximum life span (MLS)

Maximum potential years of survival

Humans: approximately 125 years

Life expectancy (LE)

Expected number of years an organism may live from a particular point in time

U.S.: women (85 years) and men (83 years)

Basic Concepts

Senescence

Cell’s progressive loss of the ability to replicate over time

Biological, intrinsic phenomenon; universal changes

Loss of physiologic reserve

Loss of ability to repair and adapt to stressors over time

Example: infections progress more severely

Multicausality

Both internal and external factors cause aging

No single cause

Theories of Aging

Programmed aging of the cell

Biological clocks regulate cell lifespan

Example: ovarian functioning decline

Telomere shortening theory

Telomere: region of repetitive nucleotide sequences at end of chromosome

Each mitotic division: chromosome shortens

Telomerase: enzyme that replaces telomeres

Theories of Aging (continued_1)

Damage-based theory of aging

Damage accumulates over time, causing errors in metabolism and regeneration

Free radical accumulation theory

Reactive oxygen species that accumulate over time leading to cell damage

Theories of Aging (continued_2)

Immunosenescence

Both innate and adaptive immunities decline

Immunization may be less effective in older adults

Signs of infection blunted (behavior changes and confusion may appear with infection)

Life-prolonging calorie-restricted diets

Limiting caloric intake (less than 60% of normal) prolongs lifespan in mice

Hypotheses: reduced free radical activity, biological waste accumulation, mitochondrial damage

Cardiovascular Changes with Age

Atherosclerosis, decreased elasticity of blood vessels, elevated BP

Fibrous tissue accumulates in heart muscle

Disruption of conduction system (arrhythmias)

Slower baroreceptor response

Increased risk for orthostatic hypotension

Decreased maximal heart rate

Respiratory Changes with Age

Decreased aerobic capacity by 10% per decade

Slower response to hypoxia and hypercapnia

Elasticity of rib cage and lungs declines

Vertebral collapse: kyphosis develops

Weakened cough reflex

Stasis of secretions

Renal Changes with Age

Loss of nephrons, decreased nephron activity

Decreased GFR and filtration

Increased risk of hyperkalemia

Lower Cr clearance

Elevated serum Cr and BUN

Decreased urine concentration (increased risk of dehydration)

Decreased ability to metabolize and excrete drugs

Increased risk drug toxicity

Multiple drugs: polypharmacy

Males

Benign prostatic hyperplasia (BPH)

Urinary symptoms

Testicular changes

Serum testosterone level decreases

Sperm volume and motility decrease

Females

Genitourinary syndrome of menopause (GSM)

Vulvovaginal atrophy

Vulvovaginal dryness, itching, soreness

Weakness of pelvic musculature, bladder, and urethra

Stress incontinence

Changes in vaginal flora

Genitourinary Changes with Aging

GI Changes with Aging

Decreased motility, increased constipation risk

Decreased strength of swallowing muscles

Presbyesophagus

LES loss of strength leading to GERD

Atrophy of stomach lining

Lack of intrinsic factor, vitamin B12 leading to pernicious anemia

Diminished HCL

Less absorption of Ca++ and Fe

GI Changes with Aging (continued)

Lactose intolerance

Diverticula formation

Less intestinal surface are for absorption

Change in flora

Insulin: increased insulin resistance

Decreased thyroid hormones cause reduced BMR

Integumentary Changes with Aging

Decreased skin turgor

Decreased elasticity

Signs of damage (UV radiation)

Replacement of skin cells declines: “thin skin”

Decreased subdermal fat

Increased susceptibility to skin breakdown

Rupture of skin blood vessels due to increased fragility

Musculoskeletal Changes with Aging

Decreased lean muscle

Decreased strength

Loss of bone mineral density

Most apparent in 10 years after menopause in women

Increased pathological fractures

Nervous System Changes with Aging

Decreased in neurotransmitter production and reception

May account for change in sleep pattern and mild memory loss

Plasticity of nervous system persists into old age

Neurological health depends on proper nutrition

Higher pain thresholds in older adults

Sense organs undergo changes

Presbyopia

Presbycusis

MODULE 8

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