What are the Results of Aging(biology of aging)

Winter 07Lecture 4 – Chapter 4

Werner’sSyndrome

Pathological Aging:Premature Aging

ProgeriaDevelopmental

•Vision•Hearing

•Taste•Smell•Skin**•Hair

•Weight

Skin The membranous tissue forming the external - covering largest organNew skin: Young skin: 3 to 4 wks Older Skin: 4 to 5 wks

Epidermis•squamous, basal cells & melanocytes Dermis •collagen (support structure, 75%)

Loss of •Collagen (thinner & finer) & elastin fibers (connective tissues more rigid, less flexible)•fat tissue•atrophy of sweat glands•blood vessels fragile (angiomas)

Lack of turnover of new cells

Hair

• Loss of melanin in follicles• life cycle of 4 to 5 years• strand become smaller • Genetic whites earlier

Height & Weight

Men-1.25 in HT

Women-2 in HT

Men & WomenMetabolism slows down 3% every 10 years so by 65 20% reduction

So, does obesity contribute to risk of death in older adults…

Diehr et al. (2002)N = 4,317 older adults 65-100 yrs

Examined the relationship between BMI and MortalityLongitudinal Study(wt/height X 704.5)

No correlation between WT & Mortality…in fact higher risk of death if lower wt.

BMI of 20 (5’5” 120 lbs) or lowerHigher mortality rate than higher BMIs

(Women)

10% or more weight loss since 50 (both men & women)Higher death rate (15.9% & 30.3%)

The Senses

•Vision•Hearing

•Taste•Smell

Visual impairment: most common sensory problem• 95% wear glasses (across cultures)• pupil 1/3 size (iris more rigid) (by 60 vs 20)• 5% cannot read• 20% cannot drive

•Vision

Normal Vision

Problem in lens Cataracts protein clumping together

Problem in the macula (fovea)Macular Degeneration: loss of acuity and center vision

• ear structures deteriorates • eardrum often thickens • inner ear bones and other structures are affected

• 30%: 65 & up significant hearing impairment

• 25%- between 65 and 74 • 50%- 75 & up difficulty hearing

• 10dB reduction in hearing sensitivity each decade after 60

• older men more likely to have hearing loss than older women

•Earlobes increases ¼ longer ( cartilage) &

fatter

•Hearing

9,000 taste buds 40 to 50 in women 50 to 60 in men

After 60 loss of sensitivity: sweet & salty 1st to go

Taste

•smell receptors decreases increases the threshold for smell• after 50 the sense of smell decreases rapidly• 80: reduced by about half

•Size increases ½ in wider & ½ in longer ( cartilage)

Smell

Interior

•Skeletal System•Heart•Brain

•Reproductive System

Skeletal System

• bone density is lost (women after menopause)• trunk becomes shorter (disks lose fluid - thinner)• vertebrae lose some of minerals (bone also becomes thinner) • spinal column becomes curved and compressed

• long bones (arms & legs) brittle (mineral loss) no change length arms and legs look longer when compared to shortened trunk.

Osteoporosis: resorption of bone by clasts = thin, fragile, brittle

Heart Generally, maintains size

• Except left ventricle walls thicken (enlarges)• Isolated systolic hypertension

Arteries• loss elasticity: “hardening of the arteries” (arteriosclerosis)

• *narrowing of passage in artery due to plaque (atherosclerosis)

120 = systolic contract pushing blood out ----- 80 = diastolic ventricles refill with blood

BP

Leading cause of death

1.

2.

3.6.

4. COPD5. Pneumonia

Brain

Max weight at 20 (3 lbs): loss of 10% over lifetime

No widespread loss of neurons!

Maintains mostNeurons:

Frontal, ParietalStriate

Loss in nucleusBasalis

Acetylchoiline

memory

Hub of motor activity:responsible for initiating and integrating movements

•become bright with age due to iron accumulation

• No health problems are associated with this change

Basal Ganglia

The MRI images below show a healthy 87 year old brain, next to a healthy 27 year old brain. (MRIs courtesy of the Oregon Brain Aging Study.)

MRI of healthy 87 year old brain, next to a healthy 27(MRIs courtesy of the Oregon Brain Aging Study.)

As the brain becomes smaller as a result of the gradual, life-long loss of brain cells, this area increases in size to fill the space

Subarachnoid

Memory center of the brain

There is some cell loss associated with healthy aging, but this by itself does not indicate significant memory loss

Hippocampus

Hollow spaces filled with CSF

Like the subarachnoid space, these spaces increase in size as the brain becomes smaller with age

Ventricles

Myelination: communication channel for the brain's information processing gray matter

White matter changes in appearance with aging. The reason for these changes is unclear, but it may be related to the normal slowing of information processing in the brain with age

White Matter

• white matter decrease

• increase in ventricles

• increases in CSF

Gray matter okay!

•Dopamine•Acetylcholine

•D2 receptorsDA slows metabolism

Aging brain plasticity

Dendrites!!

Reproductive system - Female

Females:Menopause: end of fertility

• loss of estrogen & progesterone•fat deposits in breasts•loss of skin elasticity•facial hairs

•50%: 45-50•25: before 45, 25% after

•2 to 3 years to complete No ovumDecrease in size: uterus, cervix, vagina

Andropause:

• testicular tissue mass decreases • testosterone: same decreases slightly • sperm still produced• erectile function impaired

•No abrupt change…•Fertility issues (94 yr old)

•Prostate enlarges (50%)

Reproductive system - Male

Women

• longer time to respond to sexual stimuli•orgasms less intense shorter duration

Men

• longer to achieve full erection• takes longer to orgasms • fewer genital spasms• longer to 2nd erection

 Aged 50-59

Aged 60-69

Aged 70 and older

Sexually Active *      

  Women 93% 81% 65%

  Men 98% 91% 79%

Sexually Active, reporting sexual activity at least once a week *

     

  Women 73% 63% 50%

  Men 90% 73% 58%

Sexually Active, reporting a high level of sexual enjoyment *

     

  Women 71% 65% 61%

  Men 90% 86%75%* Includes sex with a partner or alone (masturbation)

Survey of over 10,000 people (42% responding)