What is Extracellular matrix, why does it concern us and what can we do about the health of this extra cellular space (in a future post)
Cells congregate (come together) to form structural and functional associations. These are called tissues. There are four basic tissues in the body, epithelium, connective tissue, muscle and nervous tissue. All these tissues are. composed of cells and extracellular matrix (ECM). Extra being outside the cell. It is a complex environment composed of non living macromolecules created by cells which then get exported to this space outside the cell. ECM was once believed to be an inert element of tissue but now it is believed to assist in many adaptational functions of cells.
Connective tissue ECM, consists of a matrix of collagen fibres and something called ground substance. Ground substance is an amorphous gel like substance. The content includes Glycoaminoglycans, proteoglycans and glycoproteins. Which in a future post I will go further in depth into their functions. The fibres are proteins which fall into two major categories. Non elastic collagen. Which are quite flexible and that has great tensile strength. As well as elastic fibres, that can be stretched up to 150% of their resting length before breakage occurs.
The activity of ECM in the intra/extracellular activity of cells include;
- Modify the morphology and functions of cells
- Modulate the survival of cells
- Influence the development of cells
- Regulate the migration of cells
- Direct mitotic activity of the cells
- Form junctional associations with cells
A Major function of ECM is the stability it provides cells. The scaffold like environment of the collagen helps cells resist tensile forces as well the ground substance assists in the ability for cells to resist compressive forces. When compressed or heated the ground substance goes through a Thixotropic change, which is the ability for a substance to go from a solid substance to a liquid substance. Essentially when stress is applied it becomes less viscous reducing fluid flow, which is also important to have proper fluctuating fluids. Its when this ECM starts to break down that you have a poorly adapting system and cells don’t get proper information passing cell to cell through a process called “Mechanotransduction”. Mechanotransduction is the ability for mechanical tension or a stimulus to be able to pass cell to cell to encourage proper cell signalling. Allowing proper transcription of cell mediated growth factors and allow the the body recover from the stress we enact on our cells day to day. Tendon overuse injuries is a breakdown of the ECM of the tendon and mechanical strain can further change the ECM in a negative way.
A fascinating structure living in our body the ECM and its constituents vary depending on the tissue that you examine. The overarching term connective tissue relates the body as a whole as a connected whole through this vast collagenous network. Information is disseminated through chemical mediators and mechanical stimuli through link proteins such as integrins (which cells are very sensitive to mechanical stimuli)
In future posts I will go further into the various elements of this wonderful part of our body and delve deeper into the differences tissue to tissue if I can, but for now here is another basics series on a fascinating aspect of human physiology.
Crux Osteopathy 