Lecture on Aging - Chapter 2

Introduction

Chapter Focus: Physical changes during aging
Types of Aging: Primary aging and secondary aging
- Primary Aging: Universal, inevitable biological processes
- Secondary Aging: Result of environmental factors, not inevitable

Oxidative Damage
- Random cellular damage via free radicals
- Free radicals: Molecules with an unpaired electron
- Sources: Normal metabolism, diet, sunlight, pollution
- Antioxidants: Inhibit free radicals (e.g., blueberries, cherries)
- Studies: Improved longevity in rats on blueberry diet
Genetic Limits
- Max lifespan varies by species (e.g., humans: 110-120 years)
- Hayflick Limit: Human cells divide ~50 times
- Telomeres: Protective DNA sequences that shorten with age
- Stem cells: Can divide indefinitely, potential for extended longevity
Caloric Restriction
- Fewer calories associated with increased lifespan
- Rat studies: Lifespan extension with calorie reduction
- Human impact: Requires ~30% reduction, impractical long-term

Longevity: Average expected life length at a historical period
Life Expectancy: Years a person is expected to live from a certain age
Lifespan: Maximum years a species can potentially live (e.g., humans ~120 years)
Trends: Women generally outlive men due to various factors (genetic, behavioral, environmental)

Vision
- Lens thickening/yellowing, less light reaches the retina
- Reduction in dark adaptation, first sense to decline
- Presbyopia: Difficulty seeing close objects, common after 45
- Cataracts: Clouding of the lens, corrected with surgery
- Glaucoma: Increased eye pressure, can lead to blindness, serious
Hearing
- Common impairment by 65, worsens with age
- Cilia: Hair cells in cochlea that decline with loud noises
- Cochlear Function: Pressure-related, susceptible to damage
- Earbuds: Contribute to early hearing loss in current generations
Taste and Smell
- Declines significantly by age 70
- Taste buds reduce, lose sense of smell and taste
- Smokers and men tend to lose these senses more