This document discusses age-related changes to the body's systems. As people age, cells are gradually reduced leaving fewer functional cells. Lean body mass decreases while fat tissue increases. Height decreases about 2 inches by age 80 due to loss of cartilage and thinning of vertebrae. Lung capacity declines making older adults more prone to respiratory infections. Hearing and vision decline with age due to loss of cells and stiffness of tissues. The immune system becomes less effective putting older adults at higher risk for infections. Thermoregulation also decreases making temperature regulation more difficult.

1. LESSON 1
AGE-RELATED CHANGES
PREPARED BY:
CRISTIL ANN V. DESCALSOTA, RN, MN, LPT
MIDTERM

2. CHANGES TO THE BODY
•Cells
Organ and system changes can be traced to
changes at the basic cellular level. The number
of cells is gradually reduced, leaving fewer
functional cells in the body. Lean body mass is
reduced, whereas fat tissue increases until the
sixth decade of life. Total body fat as a
proportion of the body’s composition increases
(St-Onge & Gallagher, 2010; Woo, Leung, &
Kwok, 2007). Cellular solids and bone mass are
decreased. Extracellular fluid remains fairly
constant, whereas intracellular fluid is
decreased, resulting in less total body fluid.
This decrease makes dehydration a significant
risk to older adults.

3. Physical
Appearance

4. Stature decreases, resulting in a loss of
approximately 2 in. in height by 80 years of
age. Body shrinkage is due to reduced
hydration, loss of cartilage, and thinning of
the vertebrae. The decrease in stature
causes the long bones of the body, which do
not shrink, to appear disproportionately
long. Any curvature of the spine, hips, and
knees that may be present can further
reduce height. These changes in physical
appearance are gradual and subtle. Further
differences in physiologic structure and
function can arise from changes to specific
body systems.

5. RESPIRATORY SYSTEM

6. Respiratory changes that occur
with aging
The sum of these changes causes less lung expansion,
insufficient basilar inflation, and decreased ability to
expel foreign or accumulated matter. The lungs exhale
less effectively, thereby increasing the residual volume.
As the residual volume increases, the vital capacity is
reduced; maximum breathing capacity also decreases.
Immobility can further reduce respiratory activity. The
decline in ventilatory capacity is noticeable primarily
when an extra breathing demand is present, as the
lower pulmonary reserve results in dyspnea more easily
occurring. With less effective gas exchange and lack of
basilar inflation, older adults are at high risk for
developing respiratory infections. Endurance training
can produce a significant increase in lung capacity of
older adults.

7. CARDIOVASCULAR
SYSTEM

8. GASTROINTESTINAL
SYSTEM

9. Esophageal motility is affected by age.
Presbyesophagus is a condition characterized by a
decreased intensity of propulsive waves and an
increased frequency of nonpropulsive waves in the
esophagus. The esophagus tends to become
slightly dilated, and esophageal emptying is slower,
which can cause discomfort because food remains
in the esophagus for a longer time. Relaxation of
the lower esophageal sphincter may occur; when
combined with the older person’s weaker gag
reflex and delayed esophageal emptying, aspiration
becomes a risk.

10. URINARY
SYSTEM

11. REPRODUCTIVE SYSTEM

12. MUSCULOSKELETAL
SYSTEM

13. NERVOUS
SYSTEM

14. SENSORY
ORGANS

15. VISION
Presbyopia, the inability to focus or
accommodate properly due to reduced
elasticity of the lens, is characteristic of
older eyes and begins in the fourth
decade of life. The stiffening of the
muscle fibers of the lens that occurs
with presbyopia decreases the eye’s
ability to change the shape of the lens
to focus on near objects and decreases
the ability to adapt to light.

16. HEARING
Presbycusis is progressive
hearing loss that occurs as a
result of age-related changes to
the inner ear, including loss of
hair cells, decreased blood
supply, reduced flexibility of
basilar membrane, degeneration
of spiral ganglion cells, and
reduced production of
endolymph. This degenerative
hearing impairment is the most
serious problem affecting the
inner ear and retrocochlea

17. TASTE
AND
SMELL
Approximately half of all older
persons experience some loss of
their ability to smell. The sense of
smell reduces with age because of
a decrease in the number of
sensory cells in the nasal lining
and fewer cells in the olfactory
bulb of the brain. By age 80 years,
the detection of scent is almost
half as sensitive as it was at its
peak. Men tend to experience a
greater loss in the ability to detect
odors than women.

18. TOUCH
A reduction in the number of
and changes in the structural
integrity of touch receptors
occurs with age. Tactile
sensation is reduced, as
observed in the reduced
ability of older persons to
sense pressure and pain and
differentiate temperatures.
These sensory changes can
cause misperceptions of the
environment and, as a result,
profound safety risks.

19. ENDOCRINE SYSTEM
The endocrine system has groups of cells and glands that
produce the chemical messengers known as hormones. With
age, the thyroid gland undergoes fibrosis, cellular infiltration,
and increased nodularity. The resulting decreased thyroid gland
activity causes a lower basal metabolic rate, reduced
radioactive iodine uptake, and less thyrotropin secretion and
release. Protein-bound iodine levels in the blood do not change,
although total serum iodide is reduced. The release of thyroidal
iodide decreases with age, and excretion of the 17-ketosteroids
declines. The thyroid gland progressively atrophies, and the loss
of adrenal function can further decrease thyroid activity.
Secretion of thyroid-stimulating hormone (TSH) and the serum
concentration of thyroxine (T4) do not change, although there is
a significant reduction in triiodothyronine (T3), believed to be a
result of the reduced conversion of T4 to T3. Overall, the
thyroid function remains adequate.

20. INTEGUMENTARY SYSTEM
Scalp, pubic, and axillary hair thins and grays due to a progressive loss of
pigment cells and atrophy and fibrosis of hair bulbs; hair in the nose and
ears becomes thicker. By age 50 years, most white men have some degree
of baldness and about half of all people have evidence of gray hair. Growth
rate of scalp, pubic, and axillary hair declines; the growth of facial hair may
occur in older women. An increased growth of eyebrow, ear, and nostril hair
occurs in older men. Fingernails grow more slowly, are fragile and brittle,
develop longitudinal striations, and experience a decrease in lunula size.
Perspiration is slightly reduced because the number and function of the
sweat glands are lessened.

21. IMMUNE SYSTEM
The aging of the immune system, known as immunosenescence, includes a
depressed immune response, which can cause infections to be a significant risk of
older adults. After midlife, thymic mass decreases steadily, to the point that serum
activity of thymic hormones is almost undetectable in the aged. T-cell activity
declines and more immature T cells are present in the thymus. A significant
decline in cell-mediated immunity occurs, and T lymphocytes are less able to
proliferate in response to mitogens. Changes in the T cells contribute to the
reactivation of varicella zoster and Mycobacterium tuberculosis, infections that
are witnessed in many older individuals. Serum immunoglobulin (Ig) concentration
is not significantly altered; the concentration of IgM is lower, whereas the
concentrations of IgA and IgG are higher. Responses to influenza, parainfluenza,
pneumococcus, and tetanus vaccines are less effective (although vaccination is
recommended because of the serious potential consequences of infections for
older adults). Inflammatory defenses decline, and, often, inflammation presents
atypically in older individuals (e.g., low-grade fever and minimal pain). In addition,
an increase in proinflammatory cytokines occurs with age, which is believed to be
linked to atherosclerosis, diabetes, osteoporosis, and other diseases that increase
in prevalence with age.

22. THERMOREGULATION
Normal body temperatures are lower in later life than in
younger years. Mean body temperature ranges from 96.9°F
to 98.3°F orally and 98°F to 99°F rectally. Rectal and
auditory canal temperatures are the most accurate and
reliable indicators of body temperature in older adults.
There is a reduced ability to respond to cold temperatures
due to inefficient vasoconstriction, reduced peripheral
circulation, decreased cardiac output, diminished shivering,
and reduced muscle mass and subcutaneous tissue. At the
other extreme, differences in response to heat are related
to impaired sweating mechanisms and decreased cardiac
output. These age-related changes cause older adults to be
more susceptible to heat stress. Alterations in response to
cold and hot environments increase the risks for accidental
hypothermia, heat exhaustion, and heat stroke.