Cell Junctions Flashcards
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
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
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
4
Q
adhesion junction
A
- adherens
- Desmisomes
- Hemidesmisomes
5
Q
cadherin
A
holds one cell to the next, part of adhesion
6
Q
basal lamina
A
- “basement membrane” of epithelial cell
- extracelllular matrix secreted by epithelial cells
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
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
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
10
Q
disease attacking desmosome
A
- autoimmune disease that causes blistering
- epithelial cells blister because they are not held down correctly
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