POS - ECM Flashcards
Why is the ECM inportant?
It determines the physical properties of a tissue whilst providing a scaffold for its cells. The organisation of the ECM creates a functionally appropriate structure,
What is meant by “dynamic reciprocity”?
The fact that there is a reciprocal relationship between cells and their ECMs. Cells determine the ECM produced and its turnover whilst receiving signals from the ECM that regulate these.
Give an example of where cytoskeletal orientation determines ECM organisation.
Fibroblasts being stretched.
Why do GAGs have the ability to resist compressive forces?
They are highly negatively charged and thus hydrophilic giving them gel like properties.
How are proteoglycans linked to hyaluronan?
The protein core is ionically linked to hyaluronan.
Give an example of how proteoglycans regulate signalling molecules.
TGF-beta stimulates cells to synthesis ECM, but also decorin. Decorin is a PG that blocks this pathway therefore regulates its own secretion.
How can proteoglycans act as co-receptors?
When in the plasma membrane they can localise signalling molecules and facillitate effective signalling.
What makes up a collagen fibres?
3 alpha-chain polypeptides arranged in a triple helix (gamma-helix) that form into collagen fibrils that then form into collagen fibres.
What cells secrete the basal lamina?
Those for which it forms a base.
What are the three functions of the basal lamina?
- To seperate - barrier to cells
- Act as a scaffold for regenerating cells (also provide signals for repair)
- Act as a selective molecular filter.
What are the categories and classes of cell junctions?
Cell-cell, Cell-matrix
Tight
Anchoring
Gap
What are the three components of anchoring junctions?
- Intracellular attachment proteins
- Trans-membrane linker proteins (adherins/integrins)
- Actin/Intermediate filaments
What do gap junctions facilitate?
Communication through the movement of both metabolites and electrical ions.
