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Today: Epithelial Tissue Modifications of epithelium (Classification of epithelial membranes)

Today: Epithelial Tissue Modifications of epithelium (Classification of epithelial membranes) Epithelial Glands. Stratified squamous (nonkeratinized) epithelium -location, function Stratified squamous (keratinized) epithelium -keratin in cells -location, function.

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Today: Epithelial Tissue Modifications of epithelium (Classification of epithelial membranes)

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  1. Today: Epithelial Tissue Modifications of epithelium (Classification of epithelial membranes) Epithelial Glands

  2. Stratified squamous (nonkeratinized) epithelium -location, function Stratified squamous (keratinized) epithelium -keratin in cells -location, function

  3. Stratified Cuboidal Epithelium Stratified Columnar Epithelium Transitional Epithelium Pseudostratified Columnar Epithelium -ciliated

  4. What epithelia have in common: -polarity. The luminal and serosal surfaces Apical and basolateral surfaces -cell surface specializations eg. -apical domain/basolateral domain

  5. Some epithelial cells have: Microvilli -striated border, brush border, stereocillia -actin filaments cross linked and attached to apex by villin -terminal web has actin, spectrin, and intermediate filaments.

  6. Glands: Parenchyma - glands and ducts Stroma - connective tissue (CT) supporting the parenchyma

  7. Exocrine glands • secretory portion and duct portion • Endocrine glands

  8. Multicellular Exocrine Glands -Simple *tubular *branched tubular *coiled tubular *acinar *branched acinar -Compound *tubular *acinar *tubular acinar

  9. Know glands by the type of secretion: -mucous -serous -mixed glands -serous demilunes in salivary glands

  10. Know glands by the way the secretion is released: -Merocrine, by conventional exocytosis -Apocrine, a portion of the cell breaks off (lactation) -Holocrine, entire cell is released (sebaceous gland)

  11. Unicellular exocrine glands -goblet cells -

  12. Junctional Complex: Terminal bars -Occluding junctions -Adhering junctions

  13. Occluding Junction: -aka zonua occludens, tight junction -transmembrane junctional proteins, like a zipper -leakiness of the junction depends on the number of zipper rows -the branching rows of transmembrane junctional proteins can be seen by freeze fracture TEM -membrane is pentalamellar by thin section TEM

  14. Adhering Junctions: zonula adherens - encircle cells macula adherens - desmosome - like spot welds

  15. Zonula Adherens: -intercellular space is 15 - 20 nm This space contains cadherins - calcium dependent transmembrane linker proteins. -on the intracellular side, proteins, vinculin and a-actinin bind the mb to actin web

  16. Macula adherens (desmosome): -intercellular space is 30 nm -attachment plaque on the intracellular side of the mb made of desmoplakin. -cytokeratin (intermediate filaments, 10 nm) attach to the plaque. -intercellular space has desmoglein and cadherins

  17. Hemidesmosomes: Anchor epithelial cells to the basal lamina -attachment plaque with desmoplakin -IF, keratin tonofilaments don’t enter the plaque -trans-membrane linker proteins are integrins -these bind to laminin & type IV collagen of basal lamina

  18. Gap Junctions are communicating junctions -intercellular space is 2 - 3 nm -adjoining windows between cells -windows are connexons, made of protein connexin -gap junctions pass ions, small molecules (cAMP) -opening and closing of the gaps can be regulated

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