5-2. Hair, Glands, and Nails; Skin Diseases Flashcards
hair
keratinized organ derived from epidermis; strongest material in the body
Hair is found everywhere except __.
palms, nipples, soles, lips, and parts of genitals
What are the functions of hair?
protection from heat loss and UV
Keep dirt and insects out of eyes, ears and nose
Eyelashes shield eyes
Sense insects on skin
hair shaft
visible part projecting from the skin (shapes: round, oval, flat)
hair root
part of hair embedded in skin
hair follicle
structure that covers inner root sheaths extending from epidermal surface into dermis from which new hair develops.
Hair follicles are active on the scalp for __, and eyelashes and brows ___.
scalp: 6-10 years
eyelashes and brows: 3-4 months
hair bulb
lower, enlarged end of the follicle; contains a papilla providing nourishment; nerve ending wrapped around. acts as a very sensitive touch receptor.
hair matrix
cells at base of bulb responsible for growth. Produce new hair by mitosis when old one is shed. Older cells pushed up root, become increasing keratinized and die.
arrector pili
bundle of smooth muscle cells connected to each hair. Contraction pulls follicle upright and dimples skin (goose bumps) in response to cold or fear.
sudoriferous glands
sweat glands distributed all over body except nipples and parts of genitals (each person has about 3 million)
What are the two types of sudoriferous glands?
eccrine sweat gland and apocrine sweat gland
eccrine sweat gland
coiled end deep in dermis, duct opens in a pore on surface. Most numerous on palms, soles and forehead. Secrete true sweat: 99% water with salt and traces of metabolic waste
What is the function of the eccrine sweat glands?
prevent body from overheating
apocrine sweat glands
found in axillary area and anogenital area. Larger glands empty into hair follicles. Has fat and proteins, when decomposed by bacteria, produces body odor
ceruminous glands
modified sweat glands found lining external ear canals. secrete sticky, bitter substance called cerumen that deters insects and blocks entry of foreign materials
sebacious glands
secrete oily substance called sebum; found all over body except places without hair (palms and soles). Small on trunk and limbs, large on face, neck and upper chest. Are connected to each hair follicle
What are the functions of sebacious glands?
softens and lubricates skin, prevents brittle hair, slows water loss from skin
nails
hard keratinized squamos epithelium cells that form a covering over the dorsal surface of the distal end of fingers and toes
What are the functions of nails?
protect tips of fingers and toes
grasp and manipulate small objects
scratch an itch
nail body
part of nail you see; pink because of underlying blood vessels
free edge
part of the nail extending beyond the digit
nail root
part hidden under skin
lunula
white crescent at proximal border of nail body
cuticule
narrow band of epidermis folded over proximal border of nail body
nail matrix
epithelium under nail root, responsible for growth
acne
active inflammation of sebacious glands, usually caused by bacterial infection (part. staphylococeus), and can be mild or severe
What causes acne?
as white blood cells fight bacteria, pus (dead cells - bacteria and WBC) accumulate
warts
viruses invade epithelial cells and cause them to multiply rapidly > benign tumors appear, often on hands/feet.
How are warts spread?
direct contact with other humans with the papilloma virus
ringworm
group of contageous fungal infections that may appear ring shaped. As fungi feed on skin cells, red scaly itchy lesions develop. Tend to grow on moist, damp areas (btwn toes - athlete’s foot; in groin - jock itch)
skin cancer
malignant tumors arising in skin and invade other body areas
What is the most common cause of skin cancer?
Overexposure to UV rays
What are the two types of skin cancer?
basal cell carcinoma
melanoma
basal cell carcinoma
least malignant but most common form of skin cancer. Cells of stratum basale proliferate to form shiny, dome shaped nodules. Full cure by surgical removal in 99% of cases
melanoma
cancer of melanocytes, most dangerous but least common. Appears as a spreading brown/black patch that metasticizes rapidly to surrounding lymph/blood vessels.
What is the primary treatment for melanoma?
wide surgical excision of tumor followed by chemo. Early detection is key to survival
What is one rule for detecting melanoma?
ABCD Rule:
A - asymmetry (two sides do not match)
B - border irregularity (edges are indented, not smooth)
C - color (areas of different color)
D - diameter (larger than 6 mm across)
burn
tissue damage from heat, electricity, radiation or chemicals
What are the immediate dangers of burns?
loss of fluid and electrolytes > dehydration >shock and renal failure. Immediate replacement of lost fluids intravenously critical
Rule of nines
way to assess % of body burned, used to estimate fluid loss
After initial crisis has passed, the main threat of a burn is ___.
infection
first degree burn
only epidermis is damaged, local redness and swelling (eg. sunburn)
second degree burn
epidermis is destroyed, upper dermis injured. Local redness, swelling and blisters
third degree burn
epidermis and dermis are destroyed; skin is gray, cherry red or black. Requires skin grafts
