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27 Cards in this Set
- Front
- Back
peritrichial cells
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innervate hair follicles
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merkel cells
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neuroendocrine cells
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interpapillary peg
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useful for resisting shear stress along the dermis
several rows of dermal papillae work up into epidermis (secondary dermal ridge demaracation) |
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layers from dermis out to stratum corneum
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point: a continual differentiation process constantly occuring from a set of stem cells located in the stratum vasal; undergo mitosis; differentiate as they transit to surface; die by apoptosis leaving the keratin layer (protein/lipid layer)
stratum basal (stem cells); at granulosum layer you show granular elements, lamellar bodies, nucleoli flatten out; |
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stratum lucidum
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only present in thicker skin
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stratum spinosum
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lots of desmosome junctions along the stratum spinosum
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thick skin (back, palmsl soles of feet); convuluted interface; lack of hair, sweat glands are deep in dermis;
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thin skin
dense irregular connective tissue; thinner epidermis; dermis contaisn dense connective tissue; shallow epidermal ridges; thin keratin layer; hair follicles present (not in thick skin); sebaceous and sweat glands present |
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keratinocyte
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dominant cell composing stratified squamous epithelium itself;
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melanocytes
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sit down on basal laminae, generate melanin, have dendritic projections out through spinosum layers; communicate with keratinocytes (epidermal-melanin unit); keratinocytes take up melanin secreted by melanocytes = mechanism of skin pigmentation
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merkel cells
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neural crest derived; form a nerve plate w myelinated axon at the basal lamina; form mechanoreceptors
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langerhans cells
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dendritic APC that survey keratinocyte layers and are focused on the basal layer; can migrate out and make it down to a lymph organ to stimulate T cells
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two adjacent cells linked by desmosomes showing tonofilaments projecting in towards the cell; the intracellular space expresses cadherin proteins
INTEGRINS used to attach the basal layer to the basement membrane Cadherins are higher up "spines" o fstratum spinosum are cytoplasmic extensions with desmosomes Note melanocytes at basal level, melanin granules in keratinocytes |
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note nucleus in basal cell vs granulosum layer (bottom); cell in granulosum layer is in final stage of differentiation producing lamellar bodies and apoptotic mechanisms
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basal keratinocyte with anchoring filament; hemidesmosomes tie down basal layer to the dermis
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bullous pemphigold proteins
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form an aggregate structure that sits down through membrane and projects into extracellular space; in combo w integrins into basal laminae;
autoimmune dz; antibodies target BP180 and BP230 disrupts hemidesmosomes -> loss of epidermal integrity = complemtn activation, mast cell & eosinophil degranulation |
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L-DOPA pathway is precursor for..
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melanin & catecholamine synthesis
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UVB
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causes sunstan or sunburn; bleaches pre-existing melanin in keratinocytes by inducing synthesis of new melanin by melanocytes
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induction of melanin in melanocytes via melaoncyte stimulating hormone
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GPCR binds to stimulating hormone -> transcription factor activated (kreb) -> passed our of nucleus -> activates genes important for melanin synthesis
MITF; key player in inducing melanin synthesis; lack of functioning MITF = albinism and premature aging; also found in excess in melanoma |
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Turning on MITF
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Turns on genes to synthesis tyrosine hydroxylase important for the synthesis of melanin and catecholamines
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Gricellae Syndrome
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mutation in myosin 5a gene important for final transport step
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Langerhans cells
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monocyte derived; no desmosomes; can leave epidermis to lymphatic system;
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merkel cells
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nerve "twig" cut in section at the bottom of the dermis;
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point: express different kinds of keratin as you go from the basal layer to keratin layer
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along basal level of stratum; mutations in keratin 5 and 14 is a cause of epidermolysis bullosa simplex; in spiny layer stratum spinosum keratin 1 and 10 (mutations here = epidermolyitc hyperkeratosis); in stratum granulosum keratin 2e and 9 + protein filaggrin (= aggregation of keratin) - lemellar bodies express lipids responsible for cell envelope; defects in2e and 9 (epidermolytic palmoplantar keratoderma)
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point: different components fall together as cells move upwards; retain claudin-1 and claudin-4;
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structure of cornified cell envelope is a lipid layer on outersurface generated by lamellar bodies; beneath is involucrin; beneath in small proline rich proteins and loricrin; these are all cross linked together into a weave called transmutaminase; mutations in that causes specific diseases
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defects in loricrin
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vohwinkel syndrome and progressive symmetric erythrokeratodermia; lead to structural disruption of corneal layer
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in granulosum layer lamellar bodies and keratinohyaline granules = conc aggregates of granules that are secreted and cross linked
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