Hemi-desmosomes: The Coolest Sounding Cellular Junction
So what keeps your epithelial cells anchored to your basal lamina? It’s a question that, without a doubt, keeps you up all night.
A more familiar version is what keeps your skin cells from falling apart? Well as anyone studying for the USMLE can tell you, it’s a great many things!
Note: I’m thankful to live in the modern day and age when all this information is freely available and composable, thanks to the efforts of countless others who came before me. All relevant links to primary and secondary sources have been posted on the term, and for any that sources I have missed citing, I will work to update this to include those references.
Disclaimer: None of the literature contained in this article is medical advice or to be taken as medical advice. This article is for informational purposes and potentially subject to errors which I’m constantly working to correct. Consult a physician if you have a medical issue.
Basic anatomical knowledge reminds us that many of your non free floating cells (epithelial cells, skin cells, endothelial cells of your blood vessels, etc) are connected to each other by several types of cell junctions.
These cell junctions descend from the apical region of your cell (the top) down to the basal region of your cell (the bottom), and are of increasing complexity and strength. They also vary in function, from providing a selectively permeable barrier to certain types of molecules, to providing tensile strength to prevent your skin cells from separating.
One of the coolest sounding cell junctions, in my opinion, is an inter-cellular membrane protein complex called a “hemidesmosome”.
It sounds like something out of a Greek Epic, I know.
Hemi-desmosomes are different than the other kind of cell to cell junctions, in that they don’t connect cells to other cells, hence the hemi-prefix. Rather they connect to your basal lamina. Think of the basal lamina as “the rest of you” and the basal plasma membrane, pictured above in light green, as the bottom of your cells.
The hemidesmosome consists of several parts, but the most prominent are the integrin molecules. The part of the integrin complex outside of the cell, connects to the layer of connective tissue known as the basal lamina.
Within your cells the integrin molecule, at its terminal end, connect to keratin filaments, which are basically one of several fibrous proteins that provide structure to the inside of your cells.
In short, the hemi-desmosome complex anchors your cells to your connective tissues. Without them, your skin would literally fall apart, as well as many if your organ boundaries, your cardiac cells, and your blood vessels.
I mean even your urogenital tract would disassociate, which I’m sure would make some people turn their heads!
Well that’s it for my super-short nano-dissertation on connective tissue elements! Until next time…
