NR 283 – EXAM 2 (RETAKE)
Dermal appendages (1053)
The dermal appendages include the nails, hair, sebaceous glands,
and the eccrine and apocrine sweat glands. The nails are protective
keratinized plates that appear at the ends of fingers and toes. They
have the following structures: (1) the proximal nail fold, (2) the
eponychium (cuticle), (3) the matrix from which the nail grows and its
nail root, (4) the hyponychium (nail bed), (5) the nail plate, and (6) the
paronychium (lateral nail fold) (Figure 41-2). Nail growth continues
throughout life at 1 mm or less per day.
Hair color, density, grain, and pattern of distribution vary considerably
among people and depend on age, sex, and race. Hair follicles arise from
the matrix (or bulb) located deep in the dermis. They extend from the
dermis at an angle and have an erector pili muscle attached near the mid-
dermis that straightens the follicle when contracted, causing the hair to
stand up. Hair growth begins in the bulb, with cellular differentiation
occurring as the hair progresses up the follicle. Hair is fully hardened, or
cornified, by the time it emerges at the skin surface. Hair color is
determined by melanin-secreting follicular melanocytes. Hair growth is
cyclic, with periods of growth and rest that vary over different body
surfaces.
The sebaceous glands open onto the surface of the skin through a
canal. They are found in greatest numbers on the face, chest, and back,
with modified glands on the eyelids, lips, nipples, glans penis, and
prepuce. Sebaceous glands secrete sebum, composed primarily of lipids,
which oils the skin and hair and prevents drying. Androgens stimulate the
growth of sebaceous glands, and their enlargement is an early sign of
puberty.
The eccrine sweat glands are distributed over the body, with the
greatest numbers in the palms of the hands, soles of the feet, and
forehead. They open onto the surface of the skin and are important in
, thermoregulation and cooling of the body through evaporation. The
apocrine sweat glands are fewer in number but produce significantl
more sweat than the eccrine glands. They are located near the bulb of
hair follicles in the axillae, scalp, face, abdomen, and genital area. Their
ducts open into the hair follicle. The interaction of sweat with commensal
(normal) flora bacteria contributes to the odor of perspiration.
Steven-Johnson Syndrome (1065)
The most common forms of erythema multiforme are usually
associated with severe drug reactions and include Stevens-Johnson
syndrome (severe mucocutaneous bullous form involving 10% of body
surface area). It is the most common form of erythema multiforme in
children and young adults. Toxic epidermal necrolysis (TEN)
(severe mucocutaneous bullous form involving 30% of body surface
area). Cytotoxic T lymphocytes (CTLs) in an HLA-restricted fashion
mediate the immune mechanism related to drug reactions 40,41 (see
Chapter 42 for pediatric considerations).
Yeast infection (1068)
Candidiasis is caused by the yeastlike fungus Candida albicans and
normally can be found on mucous membranes, on the skin, in the
gastrointestinal tract, and in the vagina. C. albicans can, under certain
circumstances, change from a commensal (normal) microorganism to a
pathogen, particularly in the critically ill and those who are
immunosuppressed.61
Factors that predispose to infection include (1) local environment of
moisture, warmth, maceration, or occlusion; (2) systemic
administration of antibiotics; (3) pregnancy; (4) diabetes mellitus; (5)
Cushing disease; (6) debilitated states; (7) infants younger than 6
months of age, as a result of decreased immune reactivity; (8)
immunosuppressed persons; and (9) certain neoplastic diseases of the
blood and monocyte/macrophage system. The commensal (normal)
bacteria on the skin, mainly cocci, inhibit proliferation of C. albicans. C.
albicans can activate the complement system by the alternative
pathway and produce small abscesses. Candidiasis affects only the
outer layers of mucous membranes and skin and occurs in the mouth,
vagina, uncircumcised penis, nail folds, interdigital areas, and large
skin folds. Table 41-6 lists the points of differentiation of various sites
of candidiasis habitation.
TABLE 41-6
Sites of Candidiasis Infection
Site Risk Factors Clinical Manifestations Treatment
Dermal appendages (1053)
The dermal appendages include the nails, hair, sebaceous glands,
and the eccrine and apocrine sweat glands. The nails are protective
keratinized plates that appear at the ends of fingers and toes. They
have the following structures: (1) the proximal nail fold, (2) the
eponychium (cuticle), (3) the matrix from which the nail grows and its
nail root, (4) the hyponychium (nail bed), (5) the nail plate, and (6) the
paronychium (lateral nail fold) (Figure 41-2). Nail growth continues
throughout life at 1 mm or less per day.
Hair color, density, grain, and pattern of distribution vary considerably
among people and depend on age, sex, and race. Hair follicles arise from
the matrix (or bulb) located deep in the dermis. They extend from the
dermis at an angle and have an erector pili muscle attached near the mid-
dermis that straightens the follicle when contracted, causing the hair to
stand up. Hair growth begins in the bulb, with cellular differentiation
occurring as the hair progresses up the follicle. Hair is fully hardened, or
cornified, by the time it emerges at the skin surface. Hair color is
determined by melanin-secreting follicular melanocytes. Hair growth is
cyclic, with periods of growth and rest that vary over different body
surfaces.
The sebaceous glands open onto the surface of the skin through a
canal. They are found in greatest numbers on the face, chest, and back,
with modified glands on the eyelids, lips, nipples, glans penis, and
prepuce. Sebaceous glands secrete sebum, composed primarily of lipids,
which oils the skin and hair and prevents drying. Androgens stimulate the
growth of sebaceous glands, and their enlargement is an early sign of
puberty.
The eccrine sweat glands are distributed over the body, with the
greatest numbers in the palms of the hands, soles of the feet, and
forehead. They open onto the surface of the skin and are important in
, thermoregulation and cooling of the body through evaporation. The
apocrine sweat glands are fewer in number but produce significantl
more sweat than the eccrine glands. They are located near the bulb of
hair follicles in the axillae, scalp, face, abdomen, and genital area. Their
ducts open into the hair follicle. The interaction of sweat with commensal
(normal) flora bacteria contributes to the odor of perspiration.
Steven-Johnson Syndrome (1065)
The most common forms of erythema multiforme are usually
associated with severe drug reactions and include Stevens-Johnson
syndrome (severe mucocutaneous bullous form involving 10% of body
surface area). It is the most common form of erythema multiforme in
children and young adults. Toxic epidermal necrolysis (TEN)
(severe mucocutaneous bullous form involving 30% of body surface
area). Cytotoxic T lymphocytes (CTLs) in an HLA-restricted fashion
mediate the immune mechanism related to drug reactions 40,41 (see
Chapter 42 for pediatric considerations).
Yeast infection (1068)
Candidiasis is caused by the yeastlike fungus Candida albicans and
normally can be found on mucous membranes, on the skin, in the
gastrointestinal tract, and in the vagina. C. albicans can, under certain
circumstances, change from a commensal (normal) microorganism to a
pathogen, particularly in the critically ill and those who are
immunosuppressed.61
Factors that predispose to infection include (1) local environment of
moisture, warmth, maceration, or occlusion; (2) systemic
administration of antibiotics; (3) pregnancy; (4) diabetes mellitus; (5)
Cushing disease; (6) debilitated states; (7) infants younger than 6
months of age, as a result of decreased immune reactivity; (8)
immunosuppressed persons; and (9) certain neoplastic diseases of the
blood and monocyte/macrophage system. The commensal (normal)
bacteria on the skin, mainly cocci, inhibit proliferation of C. albicans. C.
albicans can activate the complement system by the alternative
pathway and produce small abscesses. Candidiasis affects only the
outer layers of mucous membranes and skin and occurs in the mouth,
vagina, uncircumcised penis, nail folds, interdigital areas, and large
skin folds. Table 41-6 lists the points of differentiation of various sites
of candidiasis habitation.
TABLE 41-6
Sites of Candidiasis Infection
Site Risk Factors Clinical Manifestations Treatment
