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114 Cards in this Set
- Front
- Back
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What is skin?
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skin = skin + derivatives
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What are skin derivatives?
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- sweat & oils glands
- hair - nails |
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What are the distinct regions of the skin?
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- epidermis
- dermis |
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What is the epithelial layer?
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thick, keratinized stratified squamous epithelium
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What is the dermis composed of?
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CT
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What are the types of epidermal skin cells?
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- keratinocytes
- melanocytes - Langerhans cells - Merckel cells |
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What is the function of keratinocytes?
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produce keratin
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What is the lifespan of keratinocytes?
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25-45 days
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What is the function of melanocytes?
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produce melanin
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Where are melanocytes located?
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deepest layer of epidermis
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What do melanocytes process?
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numerous branching processes for melanin transfer to adjacent cells
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What is the structure of Langerhans cells?
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star-shaped
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What are the characterisitcs of Langerhans cells?
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- migrate to epidermis from bone marrow
- macrophages activate immune system |
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What type of cell are Merckel cells?
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tactile cells
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Where are Merckel Cells located?
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at the epidermis/dermis boundary
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What do Merckell cells have?
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touch receptors
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What are touch receptors?
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disc-like sensory nerve endings
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What are the layers of the skin?
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- Statum corneum
- stratum lucidum - stratum granulosum - stratum spinosum - stratum basale |
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Where is the stratum corneum layer thickest?
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on palms of hand & soles of feet
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What is the stratum corneum made up of?
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dead cells filled wiht keratin fibrils
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What are the characteristics of the stratum corneum?
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strong, protective, waterproof
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What are the characteristics of the stratum lucidum?
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- no nourishment from capillaries
- few rows of clear, flat, dead, keratinocytes - keratohyaline granules parallel |
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What occurs in the stratum granulosum?
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- cells flatten
- nuclei/organelles begin to disintegrate - accumulate keratohyaline & lamellated granules |
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What is the structure of the stratum spinosum?
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web of keratin filaments attached to desmosomes
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What does the stratum spinosum contain?
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melanin granules & Langerhans cells
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Where is the stratum basale?
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- attached to dermis
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What are the characteristics of the stratum basale?
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- youngest keratinocytes
- high mitotic index - contains melanocytes and Merckel Cells |
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What is thick skin?
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five skin layers
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What is thin skin?
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4 skin layers
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What layer of skin is absent in thin skin?
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stratum lucidum
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What are the typical cells of the CT?
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- fibroblasts
- macrophages - some mast cells - WBCs |
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What is the dermis?
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- semi-fluid matrix heavily embedded with collagen, elastin & reticular fibres
- richly supplied with nerve fibers, blood & lymphatic vessels, hair follicles, oil & sweat glands |
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What are the layers of the dermis?
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- Papillary Layer
- Reticular Layer |
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What are the characteristics of the papillary layer?
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- thin, superficial layer
- interwoven mat of CT fibers - interspersed with blood vessels |
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What are dermal papillae?
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overlie dermal ridges on palms of hands, soles of feet
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What are the characteristics of the reticular layer?
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- thick, deeper layer
- has dense irregular CT - source of cleavage and tension lines - has collagen fibers |
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What is dense irregular CT?
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thick bundles of collagen fibers parallel to skin surface
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What are the function of collagen fibers?
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- give strength & resiliency
- maintain skin hydration - elastic fibers provide stretch & recoil |
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How can dermal ridges be measured?
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using:
- position - configuration - quantity - proportion - durability |
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What is the position of a dermal ridge?
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points of beginning to termination
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What is the configuration of a dermal ridge?
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- parallel
- cluster - tri-radius |
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What is the quantity of a dermal ridge?
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ridge count per square centimeter
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What is the proportion of a dermal ridge?
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share due to height, breadth, length
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What is the durability of a dermal ridge?
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permanent endocrine structures
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What are stretch marks?
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extreme stretching of the skin that results in dermal tearing
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What are blisters?
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short-term, acute trauma causing separation of epidermal and dermal layers by fluid-filled pockets
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What are flexure lines?
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dermal folds that occur at or near joints, where dermis is tightly secured to deeper structures
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What is the structure of hypodermis?
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- superficial fascia, subcutaneous tissie
- areolar CT + blood vessels & adipose tissues |
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What are the functions of the hypodermis?
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- anchors skin to udnerlying structures with ability to slide
- shock absorber - insulator - stores fat |
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What are the pigments contributing to skin colour?
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- melanin
- carotene - hemoglobin |
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What are the characteristics of melanin?
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- only pigment made in skin
- several forms - gives colours of yellow, rust, brown, black |
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What is melanin skin colour dependent on?
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- type
- relative amount - keratinocyte retention of pigment |
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What does sun damage cause?
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- clumping of elastic fibers, causing leathery skin
- depresses immune syste, - alters DNA of skin cells - melanin protects skin |
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What pigment does carotene have?
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yellow to orange
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Where is carotene found?
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in plant products
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Where does carotene deposit?
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in keratinocytes & hypodermis
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Where does hemoglobin come from?
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capillary circulation
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What colour does hemoglobin give skin?
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pinkish hue
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What is cyanosis?
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occurs when hemoglobin is poorly oxygenated
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What are the accessory structures of the skin?
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- hair and hair follicles
- nails - sweat glands |
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What are the functions of hair?
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- sense insects on skin
- guard head form physical trauma, heat loss, sun - shield eyes - filter particles form inhaled air - hard keratin |
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What does the shape of the hair shaft determine?
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if hair is straight or curly
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What is the medullar of the hair shaft?
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large cells partially separated by air spaces & absent in fine hairs
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What is the cortex of the hair shaft?
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several layers of flattened keratinocytes where pigment is
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What is the cuticle of the hair shaft?
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single layer of overlapping cells
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What are the elements of the hair structure?
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- shaft
- root - bulb - follicle - sebaceous gland |
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What is the hair shaft?
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part that projects from the skin
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What is the hair root?
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part embedded in the skin, contained within the hair follicles
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What is the hair bulb?
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expanded deep end of follicle with paillar & root hair plexus
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What is the hair follicle?
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outer CT root sheath & inner epithelial root sheath
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What is the role of the arrector pili muscle?
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contract to pull hair up and dimple skin
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What are sebaceous glands?
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holocrine glands that secrete sebum
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What is sebum?
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an oily, bactericidal substance for lubrication & waterproofing
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What is a whitehead?
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when sebaceous gland is blocked by accumulated sebum
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What is a blackhead?
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when accumulated sebum in sebaceous gland oxidizes and darkens
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What is acne?
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active inflammation of sebaceous glands accompanied by pustules or cysts on skin
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What are nails?
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scale-like modification of the epidermis
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What are the part of a nail?
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- free edge
-body - nails folds |
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What are the nail folds?
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- 2 lateral
- 1 proximal |
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What is the lunula?
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white crescent region that lies over thick nail matrix
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How are sweat glands distributed?
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over skins surface except for nipples and parts of external genitalia
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How many sweat glands do we have?
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> 2.5 million
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What are the types of sweat glands?
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- merocrine
- apocrine - modified sweat glands |
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What are the characteristics of merocrine sweat glands?
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- more common
- on palms, sole, forehead - simple, coiled tubular glands with pore at surface |
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What are the characteristics of apocrine sweat glands?
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- in axillary & anogenital areas
- larger - ducts empty into hair follicles - sweat + fatty substances & some proteins - odourless until decomposed by bacteria |
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What are the function of apocrine sweat glands?
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- activated during pain & stress
- may serve similar fucntion as scent glands in other animals |
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What are the types of modified sweat glands?
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- ceruminous
- mammary |
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What are the function of ceruminous glands?
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secrete wax
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Where is cerumen found?
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in external ear canal
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What is the function of mammary glands?
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secrete milk
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What is vellus hair?
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fine body hair of children and females
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What are the characteristics of terminal hair?
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- may be darker
- growth affected by hormones & nutrition - grows 2.5 mm per week |
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What is terminal hair?
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coarser, longer hair of eyebrows and scalp
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What is hirsuitism?
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excessive hairiness
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What is the growth cycles of terminal hair?
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active phase --> resting phase
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What has a longer active phase - eyebrows or head hair?
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head hair
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What is alopecia?
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baldness
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What are the characteristics of male pattern baldness?
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- most common type
- genetically determined - sex-influenced |
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What causes male pattern baldness?
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- delayed-action gene "switches on" in adulthood changing follicular response to DHT
- follicular growth cycle becomes so short that many hairs don't emerge from follicle before shedding |
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What are the functions of skin?
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- protection
- permeability - excretion - body temperature - cutaneous sensation - metabolic - blood reservoir |
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What are the types of barriers provide by skin?
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- physical
- chemical - biological |
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What are the chemical barriers of the skin?
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- secretions
- melanin |
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What are the physical barriers of the skin?
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- barrier to trauma & bacterial invasion
- waterproofing |
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What are the biological barriers of the skin?
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- Langerhans cells of epidermis
- macrophages in dermis |
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What is skin impermeable to?
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- gases
- fat-soluble vitamins & steroid - plant oleoresins - organic solvents - salts of heavy metals - penetration enhancers for drug administration |
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What does the skin excrete?
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- some N- containing wastes
- NaCl & H2O lost via sweat |
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What is cutaneous sensation?
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- being aware of a caress of feeling against skin
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What are the causes of burns?
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- chemical
- heat - electricity - radiation |
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What is the first concern with burns?
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- catastrophic loss of body fluids
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What is the second concern with burns?
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- renal shutdown
- electrolyte imbalance |
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What is a first degree burn?
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only epidermis
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What is a second degree burn?
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epidermis & upper dermis
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What is a third degree burn?
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entire thickness of skin
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What is the rule of nines?
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Anterior and posterior head and neck – 9%
Anterior and posterior upper limbs – 18% Anterior and posterior trunk – 36% Perineum – 1% Anterior and posterior lower limbs – 36% TOTAL – 100% |
