Chapter 23: Med Surg Flashcards
epidermis
thin, superficial layer of skin; 0.05-0.1 mm thickness and nourished by blood vessels in dermis; regenerates every 28 days
melanocytes
contained in deep basal layer (germinativum) of the epidermis; contain melanin (gives skin and hair color) and protects from UV
keratinocytes
synthesized from epidermal cells in basal layer, they move to surface of epidermis to die and form corneum (horny cell layer); protective barrier
dermis
1-4 mm thickness, 2 layers: papillae forms fingerprints and footprints and reticular layer forms collagen
collagen
forms the greatest part of the dermis and responsible for strength; composed of fibroblasts which are important for wound healing
subcutaneous tissue
not part of skin, provides insulation, provides shock absorption
sebaceous glands
prevent skin and hair from drying; abundant on face, scalp, upper chest, and back, not palms and soles
apocrine sweat glands
located in the axillae, breast, tummy, external auditory canals, and eyelids; thick milky substance and become odorous at puberty
eccrine sweat glands
widely distributed except on lips; cools the body from evaporation and excretes waste products through the pores of the skin
insensible perspiration
600-900 mL/day lost and helps maintain homeostasis through fluid and electrolyte balance
gerontologic differences with skin
decreased extracellular water and sebaceous glands, increased capillary fragility which causes bruising, increased melanocytes in basal layer which cause solar lentigines, decreased estrogen causing baldness, increased keratin causing longitudinal ridging of nails
actinic keratoses
areas of chronic sun exposure, increased risk for BCC & SCC
normal nails
160 degrees
intertriginous
skin surfaces overlap and rub on each other
primary skin lesions
occur on previously unaltered skin
secondary skin lesions
change with time or occur because of factors such as scratching or infection
macule
circumscribed, flat discoloration < 0.5 cm: freckles, petechiae
papule
elevated solid lesion up to 0.5 cm: wart, BCC
vesicle
defined collection of (serous or free fluid up to 0.5 cm: chicken pox, 2nd degree burn
plaque
circumscribed, elevated solid lesion formed by confluence of papules: psoriasis and keratoses
wheal
firm plaque caused by fluid in dermis: insect bite
pustule
circumscribed collection of leukocytes and free (purulent) fluid: acne, impetigo
fissure
linear loss of epidermis to dermis: athlete’s foot or cracks at corner of mouth
scale
excess dead epidermal cells: flaking of skin
scar
abnormal formation of connective tissue that replaces normal skin
ulcer
irregular, crater-like loss of the epidermis and dermis: pressure ulcer and chancre
atrophy
depression in skin resulting from thinning of the epidermis or dermis: aged skin, striae