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134 Cards in this Set
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integumentary system |
system that forms the external body covering, protects deeper tissues, and houses sensory receptors and sweat and oil glands; skin, hair, nails |
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Surface Area - 1.2 to 2.2 square meters Weight - 9 to 11 lbs. % of Body Weight - 7% |
Describe the skin (surface area, weight, % of body weight): |
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1. epidermis 2. dermis |
2 layers of the skin: |
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hypodermis (superficial fascia) |
subcutaneous tissue just deep to the skin, and superficial to connective tissue |
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1. stores fat 2. anchors skin 3. absorbs shock 4. insulates (reduces heat loss) |
4 functions of the hypodermis |
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epidermis |
keratinized superficial layer of the skin; avascular, receives nutrients by diffusion |
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keratinized stratified squamous epithelium |
the type of epithelium that forms the epidermis |
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1. keratinocytes 2. melanocytes 3. dendritic cells 4. tactile cells |
4 cell types found in the epidermis |
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keratinocytes |
epidermis cells that produce keratin; most common |
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keratin |
the fibrous protein that helps give the epidermis its protective properties |
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desmosomes |
tightly connect keratinocytes |
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callus |
a thickening of the epidermis caused by persistent friction |
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melanocytes |
spider-shaped epithelial cells that synthesize the pigment melanin upon sunlight stimulation |
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melanosomes |
melanin granules that accumulate on the upper side of keratinocytes, protecting DNA from UV rays |
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motor proteins |
move melanin granules along actin filaments to the end of the "spider arms" |
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dendritic cells (Langerhans cells) |
star-shaped macrophages that ingest foreign substances and play a key role in immunity; arise in bone marrow and migrate to the epidermis |
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tactile cells (Merkel cells) |
cells that combine with nerve endings to form Merkel discs (tactile discs); present at the epidermal-dermal junction |
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tactile discs (Merkel discs) |
function as sensory receptors for touch; composed of tactile cells (Merkel cells) and nerve endings |
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thick skin |
skin covering areas subject to abrasion; palms, fingertips, soles of the feet |
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1. stratum basale 2. stratum spinosum 3. stratum granulosum 4. stratum lucidum 5. stratum corneum |
5 layers (strata) of the epidermis |
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stratum basale |
epidermal layer attached to the underlying dermis; single layer of stem cells (young keratinocytes), melanocytes, and Merkel cells |
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stratum germinativum |
alternate name for the stratum basale, meaning "germinating layer" |
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stratum spinosum |
epidermal layer containing cells with weblike systems of intermediate filaments that attach to desmosomes; houses keratinocytes, melanin granules, and dendritic cells |
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stratum granulosum |
epidermal layer where keratinization begins; houses keratohyaline granules and lamellar granules |
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keratinization |
process of keratinocytes filling with the fibrous protein keratin |
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1. keratohyaline 2. lamellar |
2 types of granules found in the stratum granulosum |
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keratohyaline granules |
granules that help to form keratin in the upper layers |
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lamellar granules |
granules that contain a water-resistant glycolipid that slows water loss |
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stratum lucidum |
epidermal layer housing two to three rows of dead keratinocytes and tonofilaments; only found in thick skin |
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tonofilaments |
large arrays of special intermediate filaments caused by keratohyaline granules clinging to keratin filaments in the cells |
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stratum corneum |
outermost epidermal layer consisting of 20 to 30 layers of dead cells; protects and waterproofs |
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cornified cells (horny cells) |
the shingle-like cell remnants of the stratum corneum |
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dermis |
the strong, flexible connective tissue layer of the skin; well vascularized |
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1. papillary 2. reticular |
2 layers of the dermis |
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papillary layer |
thin superficial layer of the dermis; houses freely wandering defensive cells and small blood vessels; 20% of dermis thickness |
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dermal papillae |
projections from the papillary layer of the dermis containing capillary loops, nerve endings, and touch receptors (Meissner's corpuscles) |
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Meissner's corpuscles (tactile corpuscles) |
fine touch receptors of the papillary layer |
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friction ridges |
ridges of the dermis that press up into the epidermis; enhance grip ability, help amplify vibrations for touch receptors |
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fingerprints |
caused by sweat pores opening along friction ridges; genetically determined and unique for every person |
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reticular layer |
deeper dermal layer consisting of the cutaneous plexus and pockets of adipose cells and collagen fibers; 80% of dermis thickness |
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Pacinian corpuscles |
deep pressure receptors of the reticular layer of the dermis |
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cutaneous plexus |
the network of blood vessels that nourishes the reticular layer of the dermis |
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cleavage lines (tension lines) |
formed by less dense regions of dermal collagen fibers running parallel to the skin surface |
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flexure lines |
dermal folds that occur near joints, where the dermis is tightly secured to deeper structures |
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1. friction ridges 2. cleavage (tension) lines 3. flexure lines |
3 dermal modifications resulting in characteristic skin markings |
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striae (stretch marks) |
extreme stretching of the skin |
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blisters |
fluid-filled pockets, caused by trauma, that separate the epidermal and dermal layers |
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1. melanin 2. carotene 3. hemoglobin |
3 pigments contributing to skin color |
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melanin |
pigment that helps protect DNA from UV radiation, causing skin to darken; produced by melanocytes |
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sunspots |
small circular white spots on the skin caused by a fungal infection, not sun exposure |
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carotene |
yellow/orange pigment that accumulates in the skin, converted to vitamin A (helps with vision); found in certain plants (ex. carrots) |
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hemoglobin |
crimson-colored oxygenated pigment in red blood cells |
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cyanosis |
caused by poorly oxygenated blood resulting in a blue skin tone |
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erythema |
reddened skin caused by blushing, fever, hypertension, inflammation, or allergy |
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pallor |
pale skin while experiencing fear, anger, and certain other types of emotional stress |
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jaundice |
abnormal yellow skin tone usually caused by a liver disorder (accumulation of bile pigments) |
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bronzing |
bronze skin tone caused by Addison's disease (lack of steroid hormones) or pituitary gland tumors that secrete melanocyte-stimulating hormone |
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bruises |
black and blue marks caused by escaped and clotted blood beneath the skin (hematomas) |
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1. hair 2. nails 3. sweat glands 4. oil glands |
4 skin appendages |
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hairs (pili) |
flexible strands of dead, keratinized cells |
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1. protection 2. filtration 3. sensory 4. warmth |
4 functions of hair |
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1. shaft 2. root |
2 main regions of a hair |
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shaft |
the portion of a hair where keratinization is complete |
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root |
the portion of a hair where keratinization is still ongoing |
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1. medulla 2. cortex 3. cuticle |
3 concentric layers of a hair |
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medulla |
innermost layer of a hair consisting of large cells and air spaces; absent in fine hair |
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cortex |
bulky layer of hair consisting of several layers of flattened cells |
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cuticle |
outer layer of hair consisting of overlapping cells like shingles on a roof |
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hair follicle |
part of a hair buried in the dermis that produces the hair |
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hair bulb |
the deep end of a hair follicle |
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hair follicle receptor (root hair plexus) |
a knot of sensory nerve endings wrapped around each hair bulb; stimulated by bending the hair |
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hair papilla |
nipple-like protrusion into the hair bulb containing capillaries that supply nutrients to growing hair and signals it to grow |
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1. peripheral connective tissue (fibrous sheath) 2. glassy membrane 3. epithelial root sheath |
3 outer layers of the hair follicle wall |
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hair matrix |
the actively dividing area of the hair bulb that produces the hair by pushing up dead, keratinized cells |
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arrector pili |
a bundle of smooth muscle cells that pulls a hair follicle upright, forcing sebum out |
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vellus hair |
pale, fine hair; body hair of children and females |
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terminal hair |
coarse, long hair; eyebrows and scalp, axillary and pubic regions, face and chest (males) |
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hirsutism |
excessive hairiness, may result from an adrenal gland or ovarian tumor that secretes high levels of androgens |
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alopecia |
baldness, result of age; hairs are shed faster than they're replaced |
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male pattern baldness |
most common type of true baldness; follicular growth cycles become so short that hairs shed before they emerge |
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alopecia areata |
rare condition in which the immune system attacks the follicles and hair falls out in patches |
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nail |
clear, protective covering on the fingers and toes; a scalelike modification of the epidermis |
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1. protection 2. tools |
2 functions of the nails |
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1. free edge 2. nail body 3. root |
3 main parts of a nail |
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nail bed |
the deeper layers of the epidermis extending beneath the nail |
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nail matrix |
the thickened proximal portion of the nailbed, responsible for nail growth |
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nail folds |
skin folds overlapping the proximal and lateral borders of a nail |
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cuticle |
the proximal nail fold that projects onto the body |
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hyponychium |
the thickened region beneath the free edge of a nail |
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sweat glands (sudiferous glands) |
merocrine glands distributed over the skin responsible for perspiration; up to 3 million per person |
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myoepithelial cells |
secretory cells associated with sweat glands; contract when stimulated by the nervous sytem |
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1. eccrine 2. apocrine |
2 types of sweat glands |
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eccrine sweat glands (merocrine sweat glands) |
sweat glands abundant on the palms, soles, and forehead; simple tubular |
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sweat |
acidic eccrine gland secretion |
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1. water 2. salts 3. vitamin C 4. antibodies 5. dermcidin 6. metabolic wastes |
6 constituents of sweat |
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dermcidin |
microbe-killing peptide found in sweat |
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apocrine sweat glands |
approximately 2000 scent sweat glands confined to the axillary and genital regions, add fatty substances and proteins to sweat; "sexual scent glands" activated during adolescence |
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ceruminous glands |
modified apocrine glands lining the external ear; produce cerumen (earwax) |
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mammary glands |
specialized apocrine glands that secrete milk |
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sebaceous glands (oil glands) |
holocrine glands that secrete sebum wherever hair is found; simple branched alveolar holocrine glands; activated during adolescence |
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sebum |
an oily, bactericidal secretion that softens hair and skin |
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acne |
an inflammation of the sebaceous glands caused by bacterial infection |
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seborrhea |
pink, raised lesions on an infant's scalp caused by overactive sebaceous glands; "cradle cap" |
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1. protection 2. temperature 3. sensation 4. metabolism 5. blood reservoir 6. excretion |
6 functions of the integumentary system |
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1. chemical 2. physical 3. biological |
3 types of barriers that protect the skin |
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acid mantle |
the low pH of skin secretions |
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defensins |
antibodies secreted by the skin that punch holes in bacteria |
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cathelicidins |
protective peptides released by damaged skin that prevent infection |
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1. dendritic cells (epidermis) 2. macrophages (dermis) 3. DNA |
3 types of biological barriers in the skin |
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insensible perspiration |
routine and unnoticeable sweat; occurs in temperatures below 90° F |
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sensible perspiration |
visible sweat; occurs in temperatures above 90° F |
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cutaneous sensory receptors |
exteroreceptors responsible for cutaneous sensation |
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exteroreceptors |
receptors that respond to stimuli arising outside the body |
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1. Merkel cells (epidermis) 2. Meissner corpuscles (dermal papillae) 3. Pacinian corpuscles (dermis/hypodermis) 4. root hair plexuses (dermis) 5. nerve endings |
5 types of cutaneous sensory receptors |
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5% |
% of blood held in the dermal vascular supply |
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1. bacterial 2. viral 3. fungal |
3 types of skin infections |
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psoriasis |
characterized by reddened epidermal lesions and white patches (scales) |
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1. basal cell carcinoma 2. squamous cell carcinoma 3. melanoma |
3 major forms of skin cancer |
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basal cell carcinoma |
least malignant and most common skin cancer, 80% of cases; shiny, dome-shaped nodules arising from the stratum basale invade the dermis and hypodermis |
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squamous cell carcinoma |
second most common skin cancer; scaly, reddened papule arising from the keratinocytes of the stratum spinosum |
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melanoma |
the most dangerous skin cancer, 2-3% of cases; spreading brown to black patch arising from melanocytes |
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Asymmetry Border irregularity Color Diameter Elevation |
ABCDE rule for recognizing melanoma |
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burn |
tissue damage inflicted by intense heat, electricity, radiation, or chemicals; denatures proteins and kills cells in the affected areas |
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loss of body fluids |
immediate threat to life resulting from severe burns |
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first-degree burn |
burn damaging only the epidermis; redness, swelling, pain; ex. sunburn |
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second-degree burn |
burn damaging the epidermis and upper dermis; swelling, redness, blisters |
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partial-thickness burns |
used to describe first- and second-degree burns |
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third-degree burn |
burn affecting the entire thickness of the skin; full-thickness burn |
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eschar |
burned skin |
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ectoderm |
the primary germ layer that develops into the epidermis |
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mesoderm |
the primary germ layer originating the dermis and hypodermis |
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lanugo coat |
the coat of delicate, colorless hairs covering a fetus |
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vernix caseosa |
white substance that protects the fetus's skin when a baby is born |
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dermatitis |
scaling and various kinds of skin inflammation often occurring from age 40 and beyond |