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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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1. epidermis |
2 layers of the skin:
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hypodermis (superficial fascia) |
subcutaneous tissue just deep to the skin, and superficial to connective tissue; mainly consists of adipose tissue |
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1. stores fat |
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 |
4 cell types found in the epidermis |
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keratinocytes |
epidermal cells that produce keratin; most common |
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keratin
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the fibrous protein that helps give the epidermis its protective properties
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desmosomes
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tightly connect keratinocytes |
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callus
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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
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melanin granules that accumulate on the upper side of keratinocytes, protecting DNA from UV rays |
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dendritic cells (Langerhans cells)
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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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Merkel cells (tactile cells) |
cells that combine with nerve endings to form Merkel discs (tactile discs); present at the epidermal–dermal junction |
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Merkel discs (tactile 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
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epidermal layer attached to the underlying dermis; single layer of stem cells (young keratinocytes), melanocytes, and Merkel cells |
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stratum germinativum
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alternate name for the stratum basale, meaning "germinating layer" |
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stratum spinosum
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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
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epidermal layer where keratinization begins; houses keratohyaline granules and lamellar granules |
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keratinization
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process of keratinocytes filling with the fibrous protein keratin; begins in stratum granulosum |
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1. keratohyaline
2. lamellar |
2 types of granules found in the stratum granulosum
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keratohyaline granules
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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
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outermost epidermal layer consisting of 20 to 30 layers of dead cells; protects and waterproofs |
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cornified cells (horny cells)
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the shingle–like cell remnants of the stratum corneum
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dermis
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the strong, flexible connective tissue layer of the skin; well vascularized |
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1. papillary |
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
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projections from the papillary layer of the dermis containing capillary loops, nerve endings, and fine touch receptors (Meissner's corpuscles) |
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free nerve endings |
pain receptors located in the papillary layer of the dermis |
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Meissner's corpuscles (tactile corpuscles)
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fine touch receptors located in the papillary layer of the dermis |
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friction ridges |
skin ridges that enhance grip ability, and help amplify vibrations for touch receptors |
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fingerprints
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caused by sweat pores opening along friction ridges; genetically determined and unique for every person |
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reticular layer
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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
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deep pressure receptors of the reticular layer of the dermis
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cutaneous plexus
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the network of blood vessels that nourishes the reticular layer of the dermis |
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cleavage lines (tension lines)
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formed by less dense regions of dermal collagen fibers running parallel to the skin surface |
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flexure lines
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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)
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extreme stretching of the skin
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blisters
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fluid–filled pockets, caused by trauma, that separate the epidermal and dermal layers
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1. melanin |
3 pigments contributing to skin color |
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melanin
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pigment that helps protect DNA from UV radiation, causing skin to darken; reddish yellow to brownish black |
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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
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yellow/orange pigment that accumulates in the stratum corneum, converted to vitamin A (helps with vision); found in certain plants (ex. carrots) |
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hemoglobin
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crimson–colored oxygenated pigment in red blood cells
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cyanosis
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blue skin tone caused by poorly oxygenated blood; ex. heart failure, respiratory disorders |
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erythema |
red skin tone caused by blushing, fever, hypertension, inflammation, or allergy |
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pallor |
pale skin due to emotional stress, fear, low blood pressure, etc. |
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jaundice |
abnormal yellow skin tone usually caused by a liver disorder (accumulation of bile pigments) |
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bronzing
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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
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black and blue marks caused by escaped and clotted blood beneath the skin (hematomas)
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1. hair |
4 skin appendages that originate in the epidermis and grow down into the dermis |
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1. more durable 2. does not flake off |
2 advantages of hard keratin over soft keratin |
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hairs (pili)
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flexible strands of hard, dead keratinocytes |
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1. protection |
4 functions of hair |
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1. shaft
2. root |
2 main regions of a hair |
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shaft
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the portion of a hair where keratinization is complete
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root
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the portion of a hair where keratinization is still ongoing |
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1. medulla |
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
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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
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part of a hair buried in the dermis that produces the hair; forms in the epidermis |
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hair bulb
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the expanded 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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hair matrix
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the actively dividing area of the hair bulb that produces the hair by pushing up dead, keratinized cells |
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1. peripheral connective tissue (fibrous sheath) |
3 outer layers of the hair follicle wall
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arrector pili
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a bundle of smooth muscle cells that pulls a hair follicle upright, forcing sebum out |
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vellus hair
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pale, fine hair; body hair of children and females
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terminal hair
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coarse, long hair; eyebrows and scalp, axillary and pubic regions, face and chest (males)
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hirsutism
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excessive hairiness, caused by an adrenal gland or ovarian tumor secreting high levels of androgens |
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alopecia
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baldness as a result of age; hairs are shed faster than they're replaced |
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male pattern baldness
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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
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clear, protective covering on the fingers and toes; a scalelike modification of the epidermis |
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1. protection |
2 functions of the nails
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1. free edge |
3 main parts of a nail |
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nail bed
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the deeper layers of the epidermis extending beneath the nail
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nail matrix
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the thickened proximal portion of the nailbed, responsible for nail growth |
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nail folds (epinychium) |
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
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the thickened region beneath the free edge of a nail |
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sweat glands (sudiferous glands)
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merocrine glands distributed over the skin responsible for perspiration; up to 3 million per person |
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1. eccrine |
2 types of sweat glands
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eccrine sweat glands (merocrine sweat glands) |
simple tubular merocrine sweat glands abundant on the palms, soles, and forehead |
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sweat
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acidic eccrine gland secretion |
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dermcidin
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microbe–killing peptide found in sweat |
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apocrine sweat glands
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scent sweat glands confined to the axillary and genital regions, add fatty substances and proteins to sweat; "sexual scent glands" activated during adolescence; approx. 2000 |
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ceruminous glands
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modified apocrine glands lining the external ear; produce cerumen (earwax) |
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mammary glands
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specialized apocrine glands that secrete milk
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sebaceous glands (oil glands) |
simple branched alveolar holocrine glands that secrete sebum wherever hair is found; activated during adolescence |
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sebum
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an oily, bactericidal secretion that softens hair and skin
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acne
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an inflammation of the sebaceous glands caused by bacterial infection
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1. protection |
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
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the low pH of skin secretions
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defensins
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antibodies secreted by the skin that punch holes in bacteria
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cathelicidins
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protective peptides released by damaged skin that prevent infection |
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1. dendritic cells (epidermis) |
2 types of biological barriers in the skin |
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insensible perspiration
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routine and unnoticeable sweat; occurs in temperatures below 90° F
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sensible perspiration
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visible sweat; occurs in temperatures above 90° F
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cutaneous sensory receptors
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exteroreceptors responsible for cutaneous sensation
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exteroreceptors
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receptors that respond to stimuli arising outside the body
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1. Merkel cells (epidermis) 3. free nerve endings (dermal papillae) |
5 types of cutaneous sensory receptors |
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5%
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% 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 |
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
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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
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tissue damage inflicted by intense heat, electricity, radiation, or chemicals; denatures proteins and kills cells in the affected areas
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1. loss of body fluids (immediate) 2. loss of proteins 3. infection |
3 dangers of burns |
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infection |
leading cause of death in burn patients |
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first–degree burn
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burn damaging only the epidermis; redness, swelling, pain; ex. sunburn |
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second–degree burn
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burn damaging the epidermis and upper dermis; swelling, redness, blisters |
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partial–thickness burns
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used to describe first– and second–degree burns |
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third–degree burn
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burn affecting the entire thickness of the skin; full–thickness burn, requires skin graft |
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ectoderm
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the primary germ layer that develops into the epidermis
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mesoderm
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the primary germ layer originating the dermis and hypodermis
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lanugo coat
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the coat of delicate, colorless hairs covering a fetus |
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vernix caseosa
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white substance that protects the fetus's skin when a baby is born
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dermatitis
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scaling and various kinds of skin inflammation often occurring from age 40 and beyond |
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loop |
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whorl |
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arch |
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