sity to accumulate fat, the diminished integumen-
tary adipose tissue reduces the skin’s ability to reg-
ulate heat loss and retention. The older people get,
the greater their tendency to feel cold even when
the external environment is warm. The risk for
heat and cold injuries affecting the skin, such as
sunburn and frostbite, also increases.
By midlife even the skin of those who are not
the outdoors types usually has weathered signifi-
cant exposure to sun, wind, and chemicals that
can cause trauma and damage. ACTINIC KERATOSIS,a
condition of precancerous growths on sun-
exposed skin, and SKIN CANCERsuch as basal cell
carcinoma or squamous cell carcinoma, may man-
ifest, arising from skin damage that occurred
decades earlier. Sunscreen, the mainstay of SUN
PROTECTIONfor children today, had not yet been
developed during the childhoods of those who are
today over age 30.
Age-related changes begin to affect the hair in
midlife, too. Melanocytes, skin cells that produce
melanin, thin from the hair follicles, diminishing
the amount of pigment that appears in new hair
fibers. Reduced pigment produces hair that appears
gray; complete absence of pigment produces white
hair. These changes occur regardless of the hair’s
natural hair color. Men and women both experi-
ence patterned ALOPECIA(hair loss), though in men
the loss of hair is generally more pronounced.
Integumentary Changes in Late Life
By the seventh, eighth, and ninth decades of life,
the epidermis becomes so thin as to reveal the col-
oration of the tissues that lie beneath the skin. The
skin drapes loosely over the body, tearing and
bruising easily. Blood vessels ridge beneath the
skin like pipe cleaners under wet tissue paper,
trailing along the backs of the hands and arms and
on the lower legs and feet. Threadlike networks of
capillaries etch across the cheeks. Late in life, the
skin continues to do a remarkable job protecting
the body, yet is especially vulnerable to damage.
Maintaining Healthy Skin Across the LifespanAnti-aging remedies abound, and some—such as
those that add moisture and vitamins to the
skin—help the skin remain supple and smooth
longer in life than without their use. But the most
effective anti-aging approach is to take good care
of the skin all through life, beginning in child-
hood. Appropriate nutrition, protection from the
sun and other elements of weather, and good
hygiene are simple, yet effective, measures to keep
the skin healthy throughout life.
See also CALLUS; FITZPATRICK SKIN TYPE;
MELANOCYTE; SCAR.albinism A genetic disorder in which the
melanocytes do not produce, or produce reduced
amounts of, melanin, the chemical that deposits
pigment in cells of the SKIN, HAIR, and structures of
the EYE. Without melanin, the skin, eyes, and hair
have little or no pigment and consequently lack
color. People who have albinism typically have
light to white skin and hair, and light or no color
to the irises of the eyes (the pigmented rings
around the center of the eyes). Albinism reduces
or eliminates the skin’s ability to protect itself
from exposure to ultraviolet light, greatly increas-
ing the risk for damage such as SUNBURNand SKIN
CANCER.
The lack of pigmentation characteristic of
albinism extends to the interior of the eye as well,
resulting in VISION IMPAIRMENT. In the normal eye
the RETINA, the inner lining of the back of the eye
that receives light images and encodes them as
NERVEsignals for the OPTIC NERVEto carry to the
BRAIN, is highly pigmented such that it appears
black. The pigment suppresses extraneous light
and supports the functions of rods and cones, the
specialized cells of vision that line the retina.
Without the protection of pigment, unfocused
lightwaves bombard the retina. The brain cannot
sort the resulting nerve signals into images and
consequently fails to properly establish the neuro-
logic pathways that make vision (the interpreta-
tion of patterns of light as images) possible.
There are a number of INHERITANCE PATTERNSfor
albinism, nearly all of which are recessive (require
a defective pigmentation GENEfrom each parent).
Researchers have identified several types of gene
mutations that cause most forms of albinism.
Oculocutaneous albinism (OCA) The three
types of OCA involve the skin, hair, and eyes to
varying degrees.- OCA type 1 results from a MUTATIONof the gene
that encodes tyrosinase, an enzyme necessary
albinism 135