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20 Cards in this Set
- Front
- Back
KERATINOCYTES
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PRINCIPAL CELL OF THE EPIDERMIS
FILAMENTS MADE OF KERATIN ATTACHED BY DESMOSOMES (SPINES) |
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MELANOCYTES
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- Primary pigment-producing cells in the skin
- Dark-staining nucleus with clear cytoplasm - Wedged between keratinocytes in the basal layer - Variable number depending on region and ultraviolet light exposure - Produce and transport melanin to other cells (especially keratinocytes) - Stain with S-100 protein |
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LANGERHANS CELLS
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- Primary antigen-presenting cell of the skin
- Clear-staining cells in the suprabasilar epidermis - Markedly folded nucleus, no desmosomes - Contain a unique cytoplasmic organelle, called the Birbeck granule - Birbeck granule is a 3-dimensional, sphere-shaped entity with protruding rods that resemble a tennis racket on electron microscopy - Stain with immunohistochemical stains for CD1a and S-100 protein, and are HLA-DR positive - Dendritic cells |
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T-CELLS
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- Migrate to the thymus and differentiate
- Small, round nucleus, deeply basophilic, with a narrow rim of cytoplasm - Role in normal cutaneous immunosurveillance - Aid in delayed-type hypersensitivity reactions (e.g. poison ivy) - Accept antigen presented to them by Langerhans cells, clonally expand, and provide memory - Major cell type in cell-mediated immunity |
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B-CELLS
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- Matures in the bone marrow (“B” is for bursa of Fabricius, in birds)
- Similar histologic appearance to T-cells - Differentiate into plasma cells, which is promoted by helper T-cells - Plasma cells then produce and secrete immunoglobulin - Major cell type in humoral immunity |
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EOSINOPHILS
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- Bi-lobed nucleus
- Granules stain strongly eosinophilic - Slightly larger than neutrophils - Granules contain hydrolytic enzymes - Phagocytize immune complexes and mast cell granules - Reactive cells that play a major role in anaphylactic reactions (Type I) - Present in hypersensitivity reactions (such as to drugs or contact allergens) and parasitic infections |
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NEUTROPHILS
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- Polymorphonuclear cell
- Inflammatory and phagocytic cells - Lobulated and segmented nucleus - Granules contain enzymes - These enzymes kill microorganisms, degrade dead bacteria, break down collagen and elastin, increase vascular permeability, lyse bacterial cell walls |
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MAST CELLS
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- Oval to spindle-shaped cells
- Concentrated around blood vessels - Contain numerous cytoplasmic granules (do not stain with hematoxylin-eosin) - Granules contain serine proteases (tryptase and chymase) - Stain with methylene blue, Giemsa, and Leder stains - Degranulate after cross-linking with IgE on the cell surface - Triggering mast cell degranulation can lead to anaphylaxis |
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HISTIOCYTES AND MACROPHAGES
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- Histiocytes and macrophages are synonymous
- Bone marrow-derived precursors circulate in blood (monocytes) - Differentiate into macrophages with proper stimulation - Make up the “mononuclear phagocytic system” - Aggregates of activated macrophages are referred to as granulomas |
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apocrine
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Apocrine glands are found mostly in odor-producing areas, such as the axillary and anogenital regions, and the breasts, eyelids, and ear canals. Function, other than to cause body odor, is still unknown.
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Eccrine glands
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sweat glands engineered primarily for temperature regulation
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Sebaceous glands
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holocrine, unilobular and multilobular, and secrete sebum
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HAIR FOLLICLE CELLS
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- The hair follicle is a complicated structure composed of 3 portions: lower, isthmus, and infundibulum
- Lower portion of the hair follicle is composed of 5 portions, each with unique cell types: --- Dermal hair papilla --- Hair matrix --- The hair shaft (medulla, cortex and cuticle) --- Inner root sheath (inner root sheath cuticle, Huxley layer, Henle layer) --- Outer root sheath - Associated with the arrector pili muscle (smooth muscle) and sebaceous glands |
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ENDOTHELIAL CELLS
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- Endothelial cells line the lumens of small arteries and veins
- Contain thick cytoplasmic filaments and pinocytotic vesicles - Have a unique organelle, the Weibel-Palade body, which is an electron-dense, rod-shaped structure - Stain with immunohistochemical stains for factor VIII antigen and CD-31 - Play roles in antigen presentation and adhesion molecule function |
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NERVE CELLS
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- Composed of axons and Schwann cells (peripheral nerve sheath cells)
- Myelinated and unmyelinated nerves are present - Meissner and Vater-Pacini end organs can be seen with routine histologic staining - Finer nerves require special staining - Skin has sensory nerves and autonomic nerves - Innervate blood vessels, eccrine and apocrine glands, and hair follicles |
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Papillary dermis
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immediately beneath the epidermis
- primarily type III collagen - more cellular than the reticular dermis - separated from the deeper dermis by horizontal, superficial blood vessel plexus |
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Reticular dermis
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- the bulk of the dermis; deep to the papillary dermis
- large bundles of type I collagen fibrils and elastic fibers - blood vessels pass vertically through the reticular dermis to connect the subcutaneous horizontal plexus with the horizontal subpapillary plexus |
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Cholinergic fibers
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innervate eccrine sweat glands
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Adrenergic fibers
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innervate blood vessels (vasoconstriction), arrector pili muscles, and apocrine glands.
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Fibroblasts
Control CT matrix Near collagen and elastic fibers, help to produce them |