Showing posts with label permeability. Show all posts
Showing posts with label permeability. Show all posts

Tuesday, November 27, 2018

→ Diffusion- Chemical Science & Embalming

To be up front, do NOT consider this to be the greatest source of information about chemistry.  In fact, failing in a chemistry class among students a couple years older than I was the beginning of my chemistry education.  Let this instead be the most practical explanation of "diffusion" and why it matters to embalmers.

Diffusion, at a basic understanding, can be described as a process where molecules are evenly dispersed over time. This transport will happen from an area of high concentration to low concentration. Gravity and edema is a fitting example any embalmer can understand. Consider gravity and its affect on water retained in the body. In this example we can expect fluid to be retained in the legs.  Logically the greatest volume or concentration of fluid would be at the lowest parts of the legs. If we would elevate the legs into the air, fluid would move from a high concentration area to a lower concentration area.  To be more specific, fluid would move from the legs towards the abdomen. In science we describe this process as diffusion.

There are many factors which can influence diffusion.  Understanding these factors assists the embalmer to apply the most effective techniques.  For instance, temperature is a way to influence diffusion.  It is also a reason many experts suggest using warm water within the fluid solution. On the micro level, molecules when cold move the slowest, while molecules hot move the fastest. The movement or lack there of aides and inhibits the transport of molecules which occurs during the diffusion process. This is part of the challenge which many embalmers face during extreme refrigerated cases.

Several other factors contribute to our complete understanding of diffusion. Permeability of cell walls can be drastically affected by polar ions such as calcium, chloride or salts.  Talking permeability, smaller molecules will have an easier time passing as compared to larger molecules. Also, thicker walls are harder to pass while thinner walls are easier to pass. Considering all of this, we wouldn't be able to pass anything without force.  We measure force as pressure. Pressure is a quantitative measurement of force which can be taken at any site or location. As in our example, legs elevated, we are using gravity to generate negative pressure in the low fluid concentration area ( abdomen ) and generate positive pressure in the high fluid concentration area ( legs ). Similarly under injection we are using the pump motor to force fluid and generate postive pressure against the vascular wall. As the pressure increases, the speed at which fluid ( high concentration ) diffuses into the low concentration areas ( the tissues ) increases.

Do you agree having covered temperature, pressure and permeability as it relates to diffusion benefits embalmers? In my opinion, the preservation of not only the deceased but also the art and science of embalming depends on it. Diffusion is what embalmers today count on to saturate and restore tissue for viewing purposes.