Hair Structure

What is your hair really made up of?

Noob Knowledge

This is a very simple diagram of what people may already know about human hair. The average person would know the actual hair, the skin, and the follicle. People that are more into science or that have learned this, may know that sebum is an oil that comes from the sebaceous gland and travels up the follicle to the hair. This knowledge, is extremely basic. Hair is much more intricate and complex. Let's take a deeper look. 

A Single Hair- The Alpha Helix Coil

Even in the single hair shaft in the picture above, there is so much information behind it. 
First, it is important to understand that hair is 90% made out of a hard, fibrous protein called keratin. Keratin is made up of polypeptide chains of amino acids such as glycine, alanine, and cysteine. The individual amino acids are held together by polypeptide bonds, and there are multiple other complex bonds involved. The picture to the left shows the alpha helix which is the polypeptide chain that makes up human hair. In one single strand of hair, three alpha helices are twisted together to form a protofibril. Then, nine protofibril join together in a circle around two or more to form an 11 stranded cable that is called microfibril. Then, hundreds of these microfibrils are cemented into an irregular fibrous bundle called macrofibril. These macrofibrils are then joined to make the cortex or main body of the hair fiber. 

Broken Down

I know that information is extremely overwhelming and scary the first time you read it. So here it is broken down for you again in simpler terms:

amino acids--> polypeptide chain called keratin/ alpha helix--> d protofibril (3 twisted alpha helices --> microfibril (9 protofibrils around 2 or more in a chainlike form) --> macrofibril (hundreds of microfibrils in a bundle) --> cortex (macrofibrils joined)

Hair Layers

As shown in the diagram to the right, there are three layers to hair. Now that you know what exactly it is made of, it is time to learn about the layers of hair. As you know, macrofibrils joining together form the cortex. The cortex provides strength to the hair shaft and also determines the color and texture of your hair. This cortex  is protected by the outermost layer, the cuticle. Because the cuticle is on the outside, it has the most contact with things that can damage it. The cuticle acts as protective armor for the inner layers, which is why most haircare products seek to condition and improve the state of it. The medulla is the innermost part of the hair  which is only found in thick, large hair. You would think that it would be the most solid, core part of the hair. But as you can partially see in the picture, it is made up of a lot of empty space; it hardly contributes to the chemical or physical makeup of our hair.