Cell Junctions Flashcards

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1
Q

Epithelium

A
  • tissues that line a void in the body – tend to be held tightly together by cell junctions and rest upon a basal lamina (basement membrane)
  • have microvilli
  • prevents things from leaking into tissues
  • APICAL- top part, BASAL LAMINA- basement membrane
  • things cannot move from apical to basal
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2
Q

cellular junctions

A
  • tight junctions tend to occur up near the microvilli surface and immediately behind those are adherence junction
    1. sealing
    2. adhesion
    3. communication
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3
Q

tight junctions

A
  • near top of cell, and forms seal all the way around cells
  • nothing from the lumen can pass between the cells and get into the tissue or blood on the baso-lateral side
  • Restricts movement within the plane of the membrane such that proteins (including channels and transporters) and phospholipids in the apical membrane domain cannot freely diffuse into the baso-lateral domain and vice versa
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4
Q

adhesion junction

A
  1. adherens
  2. Desmisomes
  3. Hemidesmisomes
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5
Q

cadherin

A

holds one cell to the next, part of adhesion

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6
Q

basal lamina

A
  • “basement membrane” of epithelial cell

- extracelllular matrix secreted by epithelial cells

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7
Q

Hemidesmisomes (bottom)

A
  • adhering type of junction
  • always at the bottom basal side
  • instead of cadherin, it has integrins
  • half a demisome, but different composition
  • anchors intermediate filaments to basal lamina
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8
Q

Desmosome (anywhere)t

A
  • adhering type of junction
  • protein plaque with cadherins (connecting proteins)
  • joins intermediate filaments from one cell to another
  • can be anywhere
  • occur in spots
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9
Q

Adherens junction (top)

A
  • adhering type of junction= adhesion belt
  • bundles of actin filaments, hold cell together
  • cadherins- connecting proteins between cells
  • at the top of cell right below tight junctions
  • cancer- lose cadherin function–> cell is metastatic
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10
Q

disease attacking desmosome

A
  • autoimmune disease that causes blistering

- epithelial cells blister because they are not held down correctly

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11
Q

gap junction

A
  • plasma membrane from one cell juxtaposing plasma membrane from another cell
  • allows passage of small water soluble ions
  • connexin protein used to form it
  • cytoplasm of one cell lines up with cytoplasm of another
  • ex. found in cardiac muscle–> allows ions to flow and heart muscle gives signals through gap junctions (not nerves)
  • ex. also gap junctions in inner ear–> if you have a defect, could cause deafness
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