Chapter 5: The Integumentary System: Skin Flashcards
Epidermis
outermost superficial region
Dermis
middle region
Hypodermis
deepest region
Stratum Basale
Deepest epidermal layer firmly attached to the dermis
a single row of the youngest keratinocytes undergo rapid mitosis
Stratum Spinosum (prickly layer)
Cells contain a weblike system of intermediate filaments attached to the desmosomes
Melanin granules and langerhais cells are abundant
Stratum Granulosum (granular layer)
thin; 4-5 cell layers, drastic changes in keratinocyte appearance occurs
keratohyaline and lamellar granules accumulate in these cells
Stratum Corneum (horny layer)
outermost, 3/4 of epidermal thickeness, waterproofin, protection from abrasion/penetration, effective barrier from biological, chemical, and physical assaults
Dermis
2nd major skin region w/ strong, flexible connective tissue, cells: fibroblasts, macrophages, mast cells, white blood cells, composed of papillary and reticular
reticular layers contain sweat and sebaceous glands
Papillary layer
areolar connective tissue w/ collagen and elastic fibers, dermal papillae- peglike projections, friction ridges originate here
Reticular layer
80% of thickness of skin, dense fibrous connective tissue, collagen fibers add strength/ resiliency, elastic fibers provide stretch-recoil properties
Sweat glands
different types, secrete sweat help prevent overheating of the body, cerumen or milk
Eccrine sweat glands
found in the palms, soles of the feet, and forehead
Apocrine sweat glands
found in axillary and anogenital
Ceruminous glands
modified apocrine glands in external ear canal that secrete cerumen (ear wax)
Mammary glands
specialized sweat glands that secrete milk
Sebaceous glands
simple alveolar holocrine glands found all over the body
hormones (androgens) can stimulate secretion
secrete oil substance called sebum which helps soften and lubricate skin, bacteriostatic
Hypodermis
subcutaneous layer deep to the skin
composed of adipose and areolar connective tissue
Melanin
yellow to reddish-brown to black pigment, responsible for dark skin colors
Carotene
yellow to orange pigment, most obvious in the palms and soles of feet
Hemoglobin
red protein in red blood cels responsible for the pinkish hue of the skin
Nails
scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
hard “keratin” produced by cells of the nail matrix
Hair
dead keratinized cells produced by hair follicles
contain hard keratin
made up of the shaft projecting from the skin, and root embedded in the skin
core of medulla and a cortex and outermost cuticle
pigmented by melanocytes at base
Root Hair plexus
knot of sensory nerve ending that wraps around each hair bulb, hair acts as sensitive touch receptors
Functions of Hair
maintain warmth, alerting body to presence of insects on skin, protect the scalp
Vellus Hair
pale, fine body hair found in children and females
Terminal Hair
coarse, long hair of eyebrows, scalp, axillary, and pubic regions, armpits
Alopecia
hair thinning in both sexes
True (frank) baldness
genetically determined and sex-influenced condition
Male pattern baldness
caused by change in follicular response to DHT
Skin Functions
Protection: chemical, physical, mechanical barriers
Body Temperature: dilation (cooling) or constriction (warming) dermal blood vessels
Cutaneous sensation: exoreceptors sense touch and pain
Metabolic function: synthesis of vitamin D in dermal bloos vessels
Blood reservoir: skin blood vessels store up to 5% of the body’s blood volume
Excretion: limited amounts of nitrogenous wastes (urea) and water are eliminated via sweat
Basal cell carcinoma
least malignant, most common (80%)
stratum basal cells proliferate and invade the dermis and hypodermic, slow growing, do not metastasize, cured by surgical excision in 99% of cases
Squamous cell carcinoma
arises from keratinocytes of stratum spinosum, mostly on the scalp, ears and lower lip, grows rapidly and metastasizes if not removed, prognosis good
Melanoma
cancer of melanocytes, most dangerous, highlymetastatic, resistant to chemotherapy
asymmetry, border, color, diamete
First degree burns
only epidermis is damaged
redness, swelling, pain
Second degree burns
epidermis and upper regions of dermis are damaged
blisters appear
heeling takes weeks, no scarring if no infection
Full thickness burns
Third-degree
entire thickness of skin is damaged
gray-white, cherry red, or black
no initial edema or pain (nerve endings destroyed)
skin grafts are usually required to restore the integument
Lanugo
downy coat of delicate hairs covering fetus
Vernix casseosa
waxy substance produced by sebaceous glands that protects the skin of the fetus in amniotic fluid
Adolescence to adult
skin and hair become oiler and acne may appear
skin starts showing effects of cumulative environmental assaults around age 30
scaling and dermatitis become more common
Older age
epidermal replacement of cells, skin becomes thinner
itchy and dry skin (dec. sebum)
subcutaneous fat layer thins (cold unbearable)
Dec elasticity, loss of subcutaneous tissue- wrinkles
more susceptible to skin cancer, less hair follicles
