Term
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Definition
| Cell junction - contact point between plasma membranes of tissue cells |
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Term
| main role of TIGHT junctions |
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Definition
| prevents leakage& passage of materials between cells |
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Term
| how are tight junctions formed? |
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Definition
| plasma membranes of two cells are fused with a strip of proteins |
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Term
| two main locations (tissue + organ)where cells are connected via tight junctions |
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Definition
1. epithelium of bladder (prevents urine leakage)
2. epithelium of intestine & stomach (prevents food leakage) |
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Term
| true/false: in tight junctions the two cells are connected via plaque proteins |
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Definition
| FALSE: tight junctions DO NOT INVOLVE PLAQUE PROTEINS! |
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Term
| type of cell junction whose main role is to hold epithelial cells together |
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Definition
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Term
| role of Adherens junctions |
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Definition
| holds EPITHELIAL cells together & help them resist separation during CONTRACTILE activities (passage of foods through intestine) |
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Term
| 3-part structure of Adherens junctions |
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Definition
1. PLAQUE (dense layer of protein inside cell membrane)
2. transmembrane glycoproteins (CADHERINS): cross the plaques of the two connected cells
3. microfilaments of ACTIN extend through cytoplasm |
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Term
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Definition
| Cadherins = transmembrane glycoproteins that cross the plaques of two adjacent cells in ADHERENS junctions |
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Term
| in which cell junctions are CADHERINS found |
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Definition
| cadherins are found in Adherens junctions & Desmosomes |
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Term
| cell junction that resists cell separation and disruption during TENSION & provide cellular support for CARDIAC muscle |
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Definition
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Term
| 2 functions of desmosomes |
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Definition
1. resist cell separation and disruption during TENSION
2. cellular support of cardiac muscle |
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Term
| 3-part structure of desmosomes |
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Definition
1. Plaque
2. transmembrane glycoproteins (cadherins)
3. Intermediate filaments (Keratin) |
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Term
| from structural perspective, how are Adherens and Desmosome junctions different |
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Definition
Adherens have microfilaments made of actin.
Desmosomes have intermediate filaments made of keratin |
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Term
| two locations of desmosomes |
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Definition
1. epidermis
2. cardiac muscle cells |
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Term
| role of Hemidesmosomes? What makes them different form other cell junctions? |
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Definition
Hemidesmosomes anchor cells to the basement membrane!!!!
Hemidesmosomes DO NOT link adjacent cells! |
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Term
| type of cell junction that doesn't involve the connection of adjacent cells |
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Definition
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Term
| structure of hemidesmosomes |
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Definition
1. usually NO Plaque
2. Glycoproteins = INTEGRINS |
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Term
| what are the glycoproteins found in hemidesmosomes? |
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Definition
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Term
| where are hemidesmosomes widely distributed? |
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Definition
| within EPITHELIA (which has basement membrane) |
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Term
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Definition
| Gap junctions= tiny intercellular gap between the plasma membranes |
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Term
| which cell junction makes the small space between two cells |
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Definition
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Term
| what is specific to the structure of gap junctions |
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Definition
| gap junctions are crossed by CONNEXONS= protein channels between the two plasma membranes, filled with fluid |
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Term
| in which cell junctions are connexons found? |
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Definition
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Term
| role of connexons in gap junctions |
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Definition
| throught connexons, cells exchange ions and small molecules |
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Term
| true/false: in gap junctions the two cells are connected through plaque |
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Definition
| FALSE: There is NO PLAQUE in gap junctions!!! |
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Term
| 3 locations of gap junctions |
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Definition
1. involuntary muscle (cardiac & smooth)
2. osteocytes
3. epithelia of gut |
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