Thursday, March 11, 2010

Chemistry of skin: Desquamation

When your skin cells reach the top layer of the stratum corneum, they will sit there for about 14 days before sloughing off. This process is called desquamation or exfoliation. Interestingly enough, there is so much scientists don't know about this process. Scientists know there are enzymes that will break the bonds between the corneocytes, but there's still so much to be learned about the entire process!

The corneocytes are linked in the lower levels of our stratum corneum by corneodesmosomes (which are macromolecular glycoprotein complexes). As they move from the lower to outer region of the stratum corneum, they are degraded by enzymes, found in the intercellular spaces. The activity of these enzymes is affected by the content of the lipids found in the spaces and the water content of our skin.

Ideally our skin would have about 10% to 20% water content. When the amount falls below this, we see dry, flaky skin. The stratum corneum becomes thicker (called hyperkeratosis), and instead of detaching cell by cell, the corneoctyes detach in sheets or scales. This is why we see that white or grey flakiness on our skin!

The desquamation process varies with skin type and skin colour. Darker skin usually has a higher spontaneous desquamation rate than paler skin (up to 2.5 times faster), which can lead to increased levels of dry skin.

We can speed up this process by exfoliating through mechanical or chemical means. We can use things like alpha-hydroxy acid, salicylic acid, papaya extract, MSM or sulphur, white willow bark extract, grapeseed extract (to a minor degree), or honeysuckle extract as exfoliating inclusions in our products. Or you can use a lovely scrub, loofah, or pumice stone to get rid of those dead cells.

Join me tomorrow for more about the chemistry of your skin!

1 comment:

Sophia1105 said...

I am aware that I am a year late to post this, but just reading through all of your posts. My goodness, you are VERY knowledgeable!!! WOW!! I am trying to think back to some of my A&P classes, just wishing that you were the teacher!

Thank you, SO VERY MUCH!