11/2- Age-Related Changes in Body Physiology Flashcards

1
Q

What is Aging?

A
  • The sum of deteriorative changes with time during post-maturational life that underlie an increasing vulnerability to challenges, thereby decreasing the ability of the organism to survive
  • Aging itself does not result in disease but renders the individual more susceptible to disease
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2
Q

What is primary aging?

A
  • Primary aging changes are those directly dependent on the passage of time
  • It is often difficult to separate out primary aging from lifestyle, environmental, or unknown disease factors
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3
Q

What are some examples of primary aging?

A
  • Menopause
  • Graying of hair
  • Balding in men
  • Loss of muscle mass
  • Atrophy of the thymus
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4
Q

What are measurements of aging?

A
  • Maximum life span
  • For humans this is ~ 120 yo
  • No evidence of change in the past 3000 yrs
  • Age-Specific Mortality Rates
  • Biomarkers of Age
  • Things that vary with age and are used as surrogates
  • Physiologic Age
  • Chronologic Age
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5
Q

T/F: The max lifespan over the past 2 million years has increased

A

True

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6
Q

How has the max lifespan and median lifespan changed over the “recent past”?

A
  • Max lifespan has not changed much
  • Median lifespan has dramatically increased
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7
Q

How did age-specific mortality rates change from 1910 to 1970?

A
  • The slope (mortality rate vs. age) are parallel. Thus, age-specific mortality rates did not change much
  • Most of the improvement is due to improved childhood and obstetric care
  • Median life expectancy, however, did increase 15 yrs; BUT aging did not slow down
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8
Q

What are age-specific mortality rates by gender? Median life expectancy?

A

The age vs. mortality rates are parallel, so the “rates of aging” are the same

  • The median life expectancy for women is 8 yrs > men (just not because of difference in aging rates)
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9
Q

What are methods to increase longevity?

A
  • Decreasing body temperature
  • May only work in cold-blooded animals
  • Gene manipulations in insulin/growth hormone/IGF1/mTOR pathways
  • Works in rodents in “stressor free environment”
  • Big effect in worms and flies
  • Caloric Restriction (to 2/3 of Ad Lib diet)
  • Robust finding seems to work in almost all species; though human studies are just starting
  • Human studies underway but uncontrolled
  • Animal seem physiologically young
  • Mechanism unknown
  • AntiOxidant enzyme overexpression?
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10
Q

How did caloric restriction affect lifespan in rats?

A
  • Caloric restriction increased max lifespan 33% in rats
  • Female C3B10F1 mice subjected to restricted caloric intakes tarting at 1 mo of age live longer
  • Caloric restriction may work in Macque Monkeys as well
  • However, possibly not as well in Rhesus monkeys; they live 30-35 yrs (harder to observe)
  • Caloric restriction harms as may strains of mice as it helps
  • Snell dwarf mice have prolonged lifespan
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11
Q

T/F: decreased GH alone has been found to be adequate to prolong lifespan

A

True

  • The survival of the little mouse is found to be about 5 yrs longer
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12
Q

Do small or regular-sized baseball players live longer?

A

The smaller ones live longer

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13
Q

What was found in transgenic mice with a reduced core body temperature?

A

Increased life span (changed gene regarding brown fat)

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14
Q

What are key types of studies of aging?

A
  • Cross-Sectional: Round up every person of a given set of ages and measure variable X in them (weakness: think, in Florida would find that people are born Hispanic and die Jewish)
  • Longitudinal: Measure variable X in a group of people and come back after an interval and repeat the measurement (weakness: hard to keep track of people this long)
  • Cohort-Longitudinal: combination of the two
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15
Q

__% of the US population is expected to be > 65 yo in 2030

A

22% of the US population is expected to be > 65 yo in 2030

(in 2010 it was 14%)

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16
Q

T/F: Median survival is increasing for all Americans

A

True

  • Highest for white females
  • Lowest for black males
17
Q

There is a difference in the median survival, however, once you make it to age 80

A

IF someone makes it to 80, the average lifespan is:

  • White women: 9-10 yrs
  • White men: 7 yrs
  • Black women: 12 yrs
  • Black men: 8-9 yrs

(So even though there are fewer black women as a percentage, they live longer than others)

18
Q

Fun fact: when considering things like surgery, you should consider the top 25th percentile as having significantly different health outcomes (may be living with “inoperable” conditions much longer)

A

Yup

19
Q

What is homeostenosis?

A

There are physiologic reserves

  • Decrease with age
  • Ex) same challenge away from homeostasis may allow younger person to recover within the range of physiological reserves
  • (Think drinking with your grandfather)
20
Q

What are some eye changes that occur with age?

A
  • Periorbital tissue atrophies
  • Decreased lachrymal gland production
  • Smaller pupil even with dilators
  • Anterior chamber more shallow
  • Lens yellows (decreased transmission of blue light)
  • Lens less elastic (can’t see close objects)
  • Small decrease in static acuity - Marked decrease in dynamic visual acuity (moving objects)
  • (Accidentally shoot endangered birds instead of ducks)
  • Marked slowing of dark and light adaptation
  • Contributes to accidental falls (use a night light!)
  • Multiplicative effect of slowed rhodopsin synthesis and lesser pupillary dilation
  • Increased need for contrasting colors
  • Impaired glare discrimination
  • Really messes up driving at night
  • Modest optic neuron losses
21
Q

What is the mechanism for developing presbyopia with aging?

A

A young person can change focal length 14 diopters while the elderly can only change 1.

  • This is due to changes in the lens as well as changes in the ciliary body
  • The increase in lens rigidity may e the same process which alters lens transparency
22
Q

How does light scattering change with an aged lens?

A

The lens changes give old people problems with glare

  • They are often completely unable to see objects near a glare source
  • Ex ) headlights of an oncoming car; in a young person, the light is focused an an object near the glare source is recognized as distinct. In the old person, the lens defocuses light and the glare source becomes larger and things near it become swallowed by it
23
Q

What happens to the optic nerve with age?

A

The optic nerve atrophies with age

24
Q

What are some auditory changes that occur with age?

A
  • Decrease cerumen production
  • What is produced is often very tenacious
  • Dull, thickened, white tympanic membrane
  • Loss of Organ of Corti hair cells
  • Loss of Cochlear neurons
  • Bilateral hearing loss for high frequencies
  • Can’t hear mosquito “ring tone”
  • Drives young away from British 7-11s
  • Larger threshold to determine differences in pitch
  • Impaired ability to determine source of sound
  • Decreased speech discrimination
  • Decreased ability to focus on target sound and ignore extraneous noise (central processing auditory deficit)
25
Q

Which are heard at higher frequencies, vowels or consonants?

A
  • Consonants are at higher frequencies (harder for the elderly to hear)
  • Especially hard with f, th, s, k, g, sh…
  • Restate, don’t repeat
26
Q

Key point: central processing auditory defect (CPAD) is NOT dementia.

What is CPAD?

A
  • CPAD is impaired voice discrimination from background noise in noisy room
  • CPAD is minimally related to changes in cognitive function
  • Ability to comprehend connected speech is more impaired than the ability to understand single spoken words. Accents and varying speakers make it worse
  • Hearing aids are ineffective as they amplify both target and background

(Think of having “Little Red Riding Hood” in different voices switching between ears and having numbers/colors/letters in different voices switching as well)

  • Bedside rounds is the worse possible way to communicate with elderly patients
27
Q

What are the clinical implications of age-related changes in special senses

A
  • Perform H/P in well lit room
  • Avoid back lighting
  • Increase volume of voice not pitch, if necessary
  • Rephrase questions if misheard, do not repeat
  • Eliminate extrinsic noise
  • Let patient see your lips when speaking
28
Q

What are body composition changes that occur with aging?

  • Total water
  • Body fat
  • Muscle mass
  • Bone mass
  • Height
A
  • Total water decreased
  • Body fat increased
  • Muscle mass decreases
  • Bone mass decreases
  • Height decreases
29
Q

Body composition changes with aging in men/women? - Percent body fat - Body water

A
  • 100%+ increase in percent body fat in men
  • Older women can be 50% fat in body composition
  • Body water decreases 10-20%
30
Q

What is found with height change with age? What causes this height change?

A
  • Men from Rhondda Fach, poor miners have larger fall in height
  • Women from both towns have decreases similar to poor men

Due to:

  • Increased hip and knee flexion
  • Decreased vertebral body height
  • Vertebral disk compaction
  • Flattening of the foot arch

Real serial measures; no cohort effect

31
Q

Important to note the heterogeneity of aging

A
  • The rate of development of age-related changes is very variable in an individual
  • Interaction of past experiences with age is variable
  • Interaction of age changes and disease
32
Q

What is the equation for average aging?

A

Average aging = “Subclinical disease” + “Disuse” + “Primary aging”