why you shouldn't wash your brain with soap

I can't think of any situation where you might be inclined to soap up your brain (except maybe if you had recently been trepanned), but it is still a bad idea.

you can actually buy soap shaped like a brain here. (It smells like bubble gum!)

When used on say, an oily frying pan, soap + scrubbing will trap the oil in little units which can be rinsed off. Without soap, using only water, the oil which is hydrophobic (meaning it would rather stick to anything besides water) will stick to the pan rather than the water. 

Soap + shaking = trapped oil (source)

How does this relate to the brain? Well the cell membrane which helps give the shape to the neurons is made up of a lipid bilayer. These lipids have a hydrophobic tail (which hides in the middle of the layer) and a hydrophilic head which faces outward, just like the oil particles above.

Cell membrane (source)

So basically if you scrubbed your brain cells with soap, the membrane that holds the neuron together would be disrupted. Scientists actually use this principle to get stuff (like DNA) out of a neuron. In DNA extraction, there is a lysis step in which a detergent (like SDS) is applied to the tissue and given a good shake. This disrupts the membrane and allows access to the contents of the neuron.

You can wash your skin with soap because the living skin cells are protected by an outer dead skin cell layer. Though if you soap up too much, you can actually dry out yours skin by stripping it of lipids faster that they can be replenished. See "How much should you shower" for an excuse to stay in bed tomorrow morning rather than get up and shower.


© TheCellularScale