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31 Cards in this Set
- Front
- Back
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What are the three layers of the skin? |
* Epidermis * Dermis * Hypodermis (Sub-Q layer) |
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Describe the Epidermis. |
* Keratinized stratified squamous epithelium * Four cell types * 4-5 distinct layers |
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What are the four cell types of the Epidermis? |
* Keratinocytes * Melanocytes * Dendritic Cells * Tactile Cells |
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What are Keratinocytes? (3) |
* Most epi cells * Produce keratin * Fibrous protein that gives the epi its protective properties |
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What are Melanocytes? (3) |
* Spider shaped epi * Synthesize melanin * Found in the deepest epi layer |
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What are Dendritic Cells? (4) |
* Star shaped * Arise from bone marrow and migrate to the epi * Also called Langerhans cells * Form a continuous network |
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What are Tactile Cells? (5) |
* Also called Merkel cells * Present at the Epidermal/Dermal junction * Shaped like a spiky hemisphere * Each intimately associated with a disc-like sensory nerve ending * Sensory receptor for touch |
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What are the 5 layers of the Epidermis (starting from the bottom)? |
* Stratum Basale * Stratum Spinosum * Stratum Granulosum * Stratum Lucidum * Stratum Corneum |
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Describe the Stratum Basale. |
* One row of actively miotic stem cells * Some newly formed cells become part of the more superficial layers * Occasionally have melanocytes & dendritic cells |
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Describe the Stratum Spinosum. |
* Several layer of keratinocytes unified by desmosomes * Contains thick bundles of intermediate filaments made of prekeratin |
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Describe the Stratum Granulosum. |
* 5 layers of flattened cells * Organelles deteriorating * Cytoplasm full of lamellar granules (which release lipids) and Keratohyaline granules |
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Describe the Stratum Corneum. |
* Top layer * 20-30 layers of dead skin * Flat membranous sacs filled with keratin * Glycolipids in the ECM |
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Describe the Dermis. |
* Second major skin region * Strong, flexible CT * Creates hair follicles, oil & sweat glands, Lymphatic vessels |
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What kinds of cells are found in the Dermis? |
* Macrophages * Fibroblasts * Occasional Mast Cells * WBC |
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What is the matrix of the Dermis like? |
* Semifluid * Embedded with fibers * Binds the entire body together like a body stocking |
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Describe the Papillary layer of the Dermis. (7) |
* Thin superficial layer * Areolar CT * Fine interlacing of collagen & elastic fibers with small blood vessels * Looseness allows for phagocytes and defensive cells to wander freely in search of bacteria * Has dermal papillae (peg like projections) * Contains capillary loops * Has free nerve endings & touch receptors (Meissner's Corpuscles) |
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Describe the Reticular layer of the Dermis. |
* 80% of the thickness of the dermis * Coarse, irregularly arranged * Dense CT * ECM: Pockets of adipose cells and thick bundles of interlacing collagen fibers, parallel to the skin surface, give the skin strength & resiliency |
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What is Melanin? (3) |
* Melanin is a polymer made of tyrosine amino acids that range in color from reddish yellow to brownish black * Found in the stratum basale & spinosum * All races have about the same # of melanocytes, but the amount of melanin varies |
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What determines Skin color? (5) |
* Skin color is determined by the kind and amount of melanin made and retained. * Brown = melanin * Yellow = carotene * Pink = hemoglobin * More sun = more melanin = darker skin |
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What are the accessory structures associated with skin? (3) |
* Hair * Nails * Glands |
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Describe Hair. (2) |
* Flexible strands produced by hair follicles * Consists of dead, keratinized cells |
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What are the functions of Hair? (5) |
* Keeps us warm * Senses insects on the skin before they can bite * Scalp hair protects the head from trauma, heat loss and sunlight * Eyelashes shield the eyes * Nose hairs filter particles from the air |
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Describe Nails. |
Scale-like modification of the epidermis that forms a clear protective covering on the dorsal surface of the distal part of the finger or toe |
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Describe Sweat Glands. (3) |
* Eccrine & Apocrine * Specialized cells that contract when stimulated by the nervous system * The contraction forces sweat into and through the glands duct system to the skin surface |
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Describe Eccrine (or Merocrine) glands. (3) |
* Simple, coiled, tubular glands * Sweat: 99% water with some salt * Sweat is acidic (pH 4-6) |
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Describe Apocrine glands (6) |
* Larger than Eccrine glands * Ducts empty into hair follicles * Sweat + fatty substances + proteins * Viscous & can be milky or yellowed * No odor (but when mixed with bacteria on the skin surface = body odor) * Begins functioning at puberty, with hormones |
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Describe Ceruminous Glands. (3) |
* Found in the external ear canal * Produces ear wax * Deters insects & foreign material from entering the ear |
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Describe Sebaceous glands. (4) |
* Simple, branched, Alveolar glands * Found everywhere except soles/palms * Develop as outgrowths of hair follicles and occasionally pores * Creates pimples |
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What and where is the Arrector Pili muscle? |
* A bundle of smooth muscle cells * In the Dermis * Attached in such a way that its contraction pulls the hair follicle upright and dimples the surface = goose bumps * A way for animals to retain heat & protect themselves |
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What is Innervation? |
To supply an organ or body part with nerves to stimulate an action. |
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What is the basic structure of the Nail? (from the last finger joint out to the end of the nail) |
* Phalanx (bone of the fingertip) * Nail Matrix (buried part, proximal to cuticle) * Root of nail * Proximal nail fold (edge of skin) * Eponychium (cuticle) * Lunule (white moon) * Nail bed * Body of nail |
