Epithelium S1M1

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Epithelium S1M1
2011-04-14 17:53:50
Cell Biology

Cell Biology
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  1. What are the different tissue types in the body
    Epithelium, connective tissue, muscle, and nervous tissue
  2. What are the three different domains of the epithelium
    • Apical (lumen)
    • Lateral (between ajoining cells)
    • Basal (basement membrane side)
  3. Basal Lamina
    The basal lamina is a layer of extracellular matrix on which epithelium sits
  4. Intestine lining is replaced how often
    4 to 6 days
  5. Epithelium in the skin is replaced every
    Twenty eight days
  6. What tissue is avascular (no vessels)
  7. Principle functions of the Epithelium
    • 1. Barrier (protection)
    • 2. Secretion
    • 3. Absorption
    • 4. Transport
    • 5. Detection of sensations
  8. P.A.S Periodic acid-Schiff (PAS) is
    A staining method used to detect glycogen in tissues (shows basement membrane in epithelium).
  9. Basal Lamina is present in what cells
    • SAME
    • Schwann cells
    • Adipose cells
    • Muscle
    • Epithelia
  10. Functions of Basal Lamina
    • 1) Physical support (structural attachment)
    • 2) Limits contact – compartmentalization
    • 3) Selective barrier
    • 4) Cell to cell interaction
    • 5) Location and movement during embryogenesis
    • 6) Polarity
  11. Two types of basement membranes are
    • Renal corpuscle
    • Basement membrane of epithelium
  12. Basal Lamina has what layers
    • Lamina densa, an electron dense layer
    • Lamina lucida, an electron lucent layer
  13. Lamina lucida consists mainly of
    • Glycoproteins
    • Laminin
    • Enactin
    • Extentions of integrins and dystroglycans
  14. Lamina densa is made up of
    • Collagen type IV
    • Fibronectin
    • Perlacan
    • Heperan sulfate
    • GAG's
  15. Fibronectin is made by
    Fibroblast cells
  16. Anchoring fibrils attach
    Basal lamina to the lamina reticularis
  17. Anchoring fibrils are made of
    Collagen type VII
  18. Lamina reticularis is made of
    Reticular fibers - collagen Type III
  19. Microfibrils attach
    Basal lamina to elastic fibers
  20. Basal lamina is made by
    Epithelial cells, not fibroblasts
  21. Laminin has binding sites for
    • Collagen type IV
    • Heparan sulfate
    • Integrins of epithelial cells
  22. Heparan sulfate restricts
    Negatively charged molecules
  23. Basement Membrane is made up of
    Basal Lamina + Lamina reticularis
  24. Dystrophin does what, and lack of it results in
    Helps muscle cells bind to laminin and to actin filaments inside the cell.

    Duchenne’s muscular dystrophy, a progressive muscular weakness. (Found only in males.)
  25. Dystrophin is located on which chromosome
    X chrom
  26. Mutation of Collagen VII gene results in what condition
    • Dystrophic epidermolysis bullosa
    • An inherited blistering skin disease in which the Epithelium is detached below the B.M
  27. Determining whether Epithelia is a covering or lining is based on what
    • Number of cell layers
    • Shape of cells
    • Surface characteristics – microvilli, cilia, flagella
  28. Three surface characteristics of epith.
    Microvilli, Cilia, Flagella
  29. Simple Squamous Epithelium are found where
    • Location: parietal layer of Bowman’s capsule, lining of blood vessels (called endothelial cells), lining of alveoli
    • Function: sites for fluid, metabolite or gas exchange.
  30. Simple Cuboidal Epith are found where
    • Location: kidney tubules, covering of ovary, ducts of glands.
    • Function: protection, secretion and absorption
  31. Simple Columnar Epith are found where
    Location: stomach, small intestines, gall bladder Function: protection, secretion, absorption
  32. Pseudostratified Columnar Epith characteristics and locations they are found
    • Not all cells reach the surface
    • Nuclei are stratified at 2 or more levels
    • Cells are crowded – varying shapes
    • All cells touch the basal lamina
    • Location : trachea, epididymis, bronchioles
    • Function : protective lining, secretion, absorption
  33. Stratified Squamous Epith have what two subgroups and characteristics
    • Mucous (non- keratinized) – esophagus
    • Cutaneous (keratinized) - skin
  34. Stratified Cuboidal Epith are found where
    Ducts of sweat glands and large ducts of Exocrine glands
  35. Stratified Columnar Epith
    Ducts of large glands
  36. Transitional Epith
    • Bladder, ureter, urethra (4-6 layers)
    • Transitional because it will go through changes.
  37. Microvilli are
    Cytoplasmic extensions of cell
  38. Microvilli are made up of what
    They have a core of actin microfilaments, actin binding filaments are attached to the PM by myosin I.

    The core is attached to the actin filaments of the terminal web which contains intermediate filaments and spectrin as well
  39. What is spectrin
    Spectrin anchors the terminal web to the apical plasma membrane.
  40. What is contained in the terminal web
    • Myosin II
    • Tropomyosin
    • Spectrin
  41. Stereocilia
    Very long microvilli
  42. Microvilli and stereocilia are used for
  43. How do cilia move
    Subunit A contains a pair of dynein arms which has ATPase activity. Radial spokes project from subunit A to the central sheath.

    Subunit B has Nexin, an elastic protein, connects adjacent doublets.
  44. Kartagener’s syndrome
    Immotile cilia syndrome, results from hereditary defects of dynein (absence of dynein arms). Mucociliary transport in the respiratory epithelium is not functional. In males, this syndrome results in sterility since sperms are immotile
  45. Terminal bars have what 3 groups
    • 1. Occluding (impermeable) junctions
    • 2. Anchoring (adhering) junctions
    • 3. Communicating junctions – gap junction
  46. Tight Junction (Zonula Occludens) do what
    • Create an impermeable junction so much so that blood will go into the intercellular space and then through the cell, not between the junctions
  47. Zonula occludens (tight junctions) use what proteins to bind to each other

    The transmembrane proteins are called occludins & claudins
  48. What type of pathogens can make it through the tight junctions
    • Cytomegalovirus
    • Cholera toxins
    • These act on the junctions resulting in a permeable junction
  49. Zonula adherens
    Form a continuous lateral adhesive band that encircle & hold cells together. It is located beneath zonula occludens
  50. E- cadherins
    • These are calcium dependent
  51. Macula adherens or desmosome have what function
    These help to resist shearing forces.
  52. Pemphigus vulgaris
    Caused by autoantibodies produced against desmosomal proteins (resulting in blistering of skin)
  53. Gap Junction, nexus or communicating junctions are located in what type of cells
    Epithelia, cardiac and smooth muscle cells, and neurons

    Composed of connexins
  54. Gap junctions open or close via what conditions
    • Low pH or increase Ca+ concentration closes the channels
    • The opposite opens channels.
  55. Hemidesmosomes
    Anchor intermediate filaments of the cytoskeleton to the basement membrane.
  56. Focal adhesions
    • Anchor actin filaments of the cytoskeleton to the basement membrane.
  57. Hemidesmosome are part of what family
    Integrins found on the basal side
  58. Endocrine glands differ from exocrine in that they
    Secrete hormones directly into the vascular system, so they don’t have ducts
  59. An example of a unicellular and multicellular exocrine systems are
    • Goblet cell (Uni)
    • Pancrease (Multi)
  60. Apocrine gland is
    Bud their secretions off through the plasma membrane producing membrane bound vesicles in the lumen. One example is the arm pits.
  61. Merocrine gland is
    Excretions via exocytosis from secretory vesicles
  62. Holocrine gland is
    Rupture of the plasma membrane (oily secretions)