There are two key components to your hair structure: the hair follicle and the hair shaft. While working together, each has a distinct role in the composition of your strands, as the National Center for Biotechnological Information (NCBI) explains.
Hair Follicles
The hair follicle sits underneath the skin’s surface and extends down into the dermis layer of your skin. Each follicle has a sebaceous gland that produces lipid-rich sebum (an oil) which naturally protects the hair and moisturizes the scalp. At the base of the hair follicle is a hair bulb. This is where the actual hair growth process occurs.
Hair grows as your blood vessels deliver nutrients to the cells inside of the hair bulb. As hair cells grow, they are attached to the follicle and the older cells are pushed outwards resulting in the strand-like appearance of your hair.
Hair Shaft
The hair shaft is the hard filamentous strands visible above the skin’s surface. The shape of the hair shaft and the angle it grows from the dermis plays a major role in determining your hair type. The hair shaft is made of three layers.
The Medullar: The innermost layer is made up of the sugar and amino acids, glycogen, and citrulline.
The Cortex: The middle layer that surrounds the medulla. It contains keratin bonds that aid in elasticity and melanocytes, special cells that produce melanin pigment that determines hair color.
The Cuticle: The outermost layer of the hair. It’s covered by a single molecular layer of lipids that repels water and gives hair its shine.
Source: L'Oréal
