Anatomy 101 - A look at the Hair Strand from Root to Tip

What's a hair blog without taking a look at the strand itself? 

This post leans more to the scientific side, learning about the strand, thus providing a greater understanding into why we utilize the techniques and products we do. This is not my area of expertise, nonetheless, I'll share what I do know with you, cuz' that's what I do :-) Let's get started. 

The Follicle 

A strand of hair is much more than the eyes can behold. As a matter of fact, the only living part of a strand of hair is below the surface of the scalp. Hair growth starts in follicles found in the dermis. These contain hair bulbs formed by actively growing cells. These cells produce hair fibers, primarily made up of protein, particularly keratin. At the base of the hair bulb is the dermal papilla containing a vessel tuft, which provides nourishment to growing hairs. Within the skin, sheaths cover the hair follicles, the most important of which is the sebaceous gland, which produces and secretes the natural oils lubricating hairs called sebum. 

The Shaft

This is the part of the hair seen above the skin.  It is made up of dead cells that have turned into keratin and binding material, along with small amounts of water. The hair shaft consists of three layers

1. The innermost layer - the medulla, seen only in large and thick hairs. 
2. The middle layer - the cortex, made of keratin fibers which gives strength, color and texture to a hair fiber. 
3. The outermost layer - the cuticle. This thin and colorless layer made up of between six to ten overlapping layers of long cell remnants, serves as a protection to the cortex. 

Hair growth cycle 

Each hair follicle lives in a cycle (which is genetically determined) consisting of 3 stages: 

• ANAGEN (GROWING) STAGE typically lasts about 3 to 5 years. 
• CATAGEN (INTERMEDIATE) STAGE - This is the transition period where hair follicles prepare themselves for the resting phase. This stage usually lasts about 1 to 2 weeks. 
• TELOGEN (RESTING or SHEDDING) STAGE - It is usually 3 to 4 months in length and at the end of this period older hairs that have finished their life will fall out and newer hairs will begin to grow. 

The growing (anagen) phase constitutes about 90% (1000 days or more) of the growth cycle of a hair follicle, while intermediate (catagen phase; 10 days) and shedding (telogen phase; 100 days) phases constitute only 10% of it. That is, at a given time, about 10% of hair follicles are in the intermediate and shedding phases; thus, not growing. These hair follicles, however, are randomly distributed over the scalp, so that no bald spots are seen. 

(Credit )

I hope this simplified look at the strand enlightens you about your hair so you can make educated decisions on your hair journeys.

XOXO,

Abbi