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Definition
| immune response through macrophages, regulation of temperature and hydration, excretion of metabolites, maintenance of homeostasis, protection from biological/chemical/physical agents, and sexual signaling (including pigmentation as a sign of health and sex pheromone production) |
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| epithelial layer of ectodermal origin, stratified squamous, avascular |
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| layer of connective tissue of mesodermal origin, vascular |
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| also known as subcutaneous tissue, not considered skin proper, formed by loos connective tissue typically containing adipose cells |
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| main cells making up skin, actively divide at barrier between epidermis and dermis, produce keratin, contain most of the melanin in skin |
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| contains 5 layers of stratified squamous epithelium, seen on hands and feet, hairless, granulosum and corneum are more developed |
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| contains 4 layers, no stratum lucidum, contains hair follicles in most locations (few exceptions) |
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| deepest layer of epidermis, single layer of basophilic columnar or cuboidal cells, mitotically active, connected to basal membrane by hemidesmosomes, anchor epidermis to dermis |
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| second deepest layer, several layers of more flattened cells connected by numerous desmosomes (which are bound to the cytoskeleton by tonofibrils), desmosomes give appearance of processes or "spines" |
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| 3 to 5 layers of polygonal cells filled with basophilic keratohyaline granules containing flaggrin intermediate filaments and other proteins that associate with keratin in tonofibrils, cells also contain lamellar granules filled with lipids (visible by TEM only), denucleation first seem in this layer |
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| found in granulosum cells, contain filaggrin |
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| found in granulosum cells, contain lipids, contents are released into intercellular spaces and function as barrier against water loss through the skin |
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| only found in thick skin, few layers of extremely flattened eosinophilic epidermal cells, also called transitional layer, 2nd layer from surface |
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| 15-20 layers of flattened, non-nucleated keratinized cells aka squames, outer-most layer |
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| cells derived from neural crest, round cells w/ cytoplasmic projections, scattered among basale cells, produce/secrete melanin, transfer melanin through cytocrine secretion |
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| main structural protein of epidermis, functions in maintaining the water barrier |
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| protein synthesized from tyrosine, moved toward surface of skin to protect cells from UV damage, determines skin color |
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| derived from bone marrow, star-shaped, mainly in stratum spinosum, function as antigen-presenting cells for T lymphocytes |
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| modified epidermal cells in the stratum basale, present in thick skin, contain dense-cored neurosecretory granules, associate closely with expanded terminal bulb of afferent myelinated nerve fibers, make up Merkel's corpuscle |
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| receptor for tactile sensation, part of diffuse neuroendocrine system |
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| connective tissue linking epidermis and hypodermis, made up of papillary and reticular layers, vascular, contains collagen 1 and 2, important in temperature regulation |
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| most superficial layer of this structure, immediately beneath epidermis, made up of loose connective tissue, has network of collagen 1 and elastic fibers, has anchoring fibrils of collagen 7 that insert into the basal lamina and connect epidermis and dermis, has nerve processes/blood vessels supplying but not penetrating epidermis |
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| closer to hypodermis, thickness varies in different parts of the body (but always thicker and less cellular than other layer of dermis), made up of dense connective tissue w/ type 1 collagen and elastic fibers w/ regular orientation |
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| important surgical landmark, creates tension in skin w/ connective tissue fibers, found in reticular layer, following them while making incisions allows faster healing |
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| arteries and veins surrounded by connective tissue capsules, function to regulate body temperature |
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| network of blood vessels located immediately between the papillary and reticular layers of dermis, projects papillary loops towards epidermis |
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| network of blood vessels located between dermis and hypodermis |
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| 3 present in skin, 2 accompany arterial plexi, one exists in middle of dermis |
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| arteriovenous anastomoses |
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Definition
| connection between arteries and veins in dermis, also important in body temperature regulation |
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| terminate in stratum granulosum, do not have Schwann cell investment, allow multiple sensations including fine touch/heat/cold |
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| encapsulated in connective tissue, large ovoid structures located in deeper dermis and hypodermis, myelinated nerve ending surrounded by capsular structure, respond to pressure and vibration |
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| tapered cylindrical receptors for low-frequency touch stimuli, oriented perpendicular to skin surface, found in papillary layer of hairless skin |
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| elongated fusiform structures, function as mechanoreceptors in skin |
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| epidermal evaginations responsible for production and growth of a hair, separated from dermis by acellular hyaline layer, has terminal dilation called the hair bulb that contains capillary network, found in root sheath, is a continuation of basal and spinous layers of epidermis |
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| acellular hyaline layer surrounding hair follicle formed by thickened basement membrane, surrounded by connective tissue sheath |
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| associated with hair follicles, release sebum into infundibulum (pilosebaceous canal surrounding the hair) |
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| keratinized filamentous structures consisting of three layers: medulla, cortex, and cuticle |
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| central part of hair shaft containing large/vacuolated/moderately keratinized cells |
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| middle layer of hair, contains cuboidal cells that differentiate into keratin-filled cells |
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| outermost layer of hair, contains squamous cells |
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| active growth of hair follicle occurs, has hair bulb at this time, lasts for 3-6 years |
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| transitional phase of hair cell development, lasts 1-2 weeks, apoptosis-driven involution occurs, ends active growth phase, club hair forms as bulb degenerates |
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| resting phase of hair follicle development, lasts 5-6 weeks, separation between secondary germ cells and dermal papilla seen |
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| plates of keratinized epithelial cells containing hard keratin, composed of roots, matrices, plates, and beds |
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| proximal part of nail, hidden in nail groove, constant addition of cells and their keratinization in this area accounts for growth of nail |
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| formed by dividing cells that cornify, forming proximal part of nail plate, contains variety of cells (stem cells, melanocytes, Merkel cells, and Langerhans cells) |
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| main part of nail, specialized stratum corneum, contains hard keratin in cells, cells do not desquamate |
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| area of skin where nails rest, formed by stratum basale and spinosum |
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| cells that make up sebaceous glands, produce sebum, make up acinar/exocrine glands, undergo holocrine secretion, found in thin skin |
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Definition
| 2 types of glands, secrete sweat |
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| merocrine/eccrine sweat glands |
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Definition
| widely distributed, coiled, have small lumen, made up of stratified cuboidal epithelium, innervated by cholinergic fibers, embedded in dermis, contain dark and clear cells |
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Definition
| confined to axillary and perineal regions of body, development dependent on sex hormones, have large lumen, made of simple cuboidal epithelium, innervated by andrenergic nerve endings, tubular glands associated with hair follicles, embedded in dermis and hypodermis, viscous secretion is initially odorless but acquires odor as result of bacterial activity, also produces pheromones |
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Definition
| found in merocrine sweat glands, contain secretory granules composed of glycoproteins |
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Definition
| found in merocrine sweat glands, devoid of secretory granules, secrete watery component of sweat |
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Definition
| involves removal of damaged collagen fibers by macrophages and proliferation of fibroblasts and production of new collagen/ECM components |
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| requires proliferation of basal keratinocytes in stratum germinativum of undamaged skin, covering of wound w/ scab, migration of new keratinocytes beneath scab and across surface of wound, proliferation/differentiation of keratinocytes to restore layers, and detachment of scab |
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Term
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Definition
| steps include transient vasodilation, vasoconstriction/clot formation, inflammatory response, proliferation of cells, and remodeling |
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Term
| Malphigian layer of epidermis |
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Definition
| basal and spinous layers of epidermis found to differentiate into many cell types in body, adult stem cell potential |
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Definition
| abnormalities of dermal-epidermal junctions, include bullous pemphigoid and pemphigus |
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Definition
| blistering disorder in which hemidesmosomes form incorrectly, epidermis detaches from dermis |
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| blistering condition caused by loss of intercellular junctions among keratinocytes, affects epidermis, increases sensitivity to light |
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Definition
| disease increasing number of proliferating cells in stratum basale and spinosum and decreased cycle time of cells, increased epidermal thickness and more rapid renewal occurs, nuclei found in stratum corneum (parakeratosis) |
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Definition
| tumor cells originate from basal epidermal cells |
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| tumor cells originate from squamous cells in the spinosum |
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Definition
| tumor cells originate from melanocytes |
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| surgical technique in which individual layers are removed piece by piece and viewed under a microscope for evidence of cancer, wound is closed when no cancerous cells are present |
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Term
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Definition
| silver hair patches are present on affected individuals, immune problems common, Rab27a is defective in melanocytes, melanosomes fail to be distributed to keratinocytes |
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Term
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Definition
| melanocytes are defective either in parts or whole body, no melanin is produced |
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Definition
| microscopically visible bundles of keratin filaments, used in desmosomes in skin |
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Definition
| always found between stratum basale and papillary layer of dermis, composite structure of basal lamina and reticular lamina, nutrients must diffuse through this layer |
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| web of sensory fibers surrounding the bases of hair follicles, detects movement of hairs |
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| muscle associated with hair follicle, allows hair to become erect, seen in "goosebumps" on skin |
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Definition
| epidermal fold of skin going under nail plate, nail eventually becomes free of nail bed here |
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| also known as the cuticle, epidermal stratum corneum extending from the proximal nail fold |
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| found in basal lamina of sweat glands, produce contractions that facilitate secretion into the ducts |
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