NR 283 EXAM 2 RETAKE

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 reactions40,41 (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.