Studied by 0 people
Looks like no one added any tags here yet for you.
what is extracellular matrix
network of extracellular macromolecules such as collagen, enzymes and glycoproteins - provide structural and biochemical support of surrounding cells
what is extracellular matrix made up of
basement membranes - thin, fibrous tissues that separate epithelia, mesothelial and endothelia and the fibrillar matrix which is 3D and contains collage i, fibronectin, elastin and proteoglycans
what is the basement membrane made up of
basal lamina - secreted by epithelial cells - composed of laminin and collagen type 4 and reticular lamina - connective tissue secreted by reticular cells - thin branching structure of collagen type 3
cell adhesion
where cells adhere
cell junction
structures which enable cell adhesion
desmosomes
- pairs of dark disk button structure at cell-cell contacts
1. helps connect cells to each other
hemisdesmosomes
link cells to the ECM eg the basal lamina, 1. connects cells to the basal lamina
2. desmosomes and hemidesmosomes anchor intermediate filaments inside the cell
3. intermediate fiber networks of adjacent cells are indirectly connected to, one another through desmosomes and to basal lamina through hemidesmosomes - this mechanically strengthens the entire epithelial tissue
4. defects of the intermediate fibers, desmosome, hemidesmosome or basal lamina could lead to fragility of skin or other epithelia.
tight junction
- surrounds apical circumference of cell that sits tight like a headband
- its function is to be a fence - controls flow direction -apical and basolateral membrane proteins cannot diffuse beyond
- be a barrier - keeps molecules in the body and block harmful ones
gap junctions
- canal/pores between cells - controls permeability
- they form pores penetrating neighbouring cells
- only ions and small molecules can pass through
adherents junction
- sits under the tight junction
- squeezes cells due to underlying actomyosin bundle
- provides mobile force for epithelial folding
- maintain cell to cell adhesion in epithelial cells
e-cadherin
main component of adherent junctions, causes cell sorting
ca2+ alters the cadherin structure and activity
also component of desmosomes
integrins
component of hemidesmosomes
focal adhesion
connects cell to ECM
1. Integrin ( transmembrane protein ) binds to ecm outside of cell
2. connected to actin filaments by linker proteins - inside plasma membrane
3. can generate movement
4. pivotal to force transduction and migration of cells
