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The Hair Cycle: The Growth and Shedding of Hair

Written by: Angyelisa Hernandez


Everyone’s hair is unique because we mostly have different hair structures, textures, lengths, colors, and strands of hair. Hair is made of keratin, a protein that grows from the dermis (middle layer of tissue). Proper nutrition and care are needed to maintain healthy hair.

A normal and healthy hair cycle goes through 3 phases:


1. Anagen or growth

2. Catagen or transitional phase

3. Telogen or resting phase



Anagen Phase

Normal and healthy hair is in the anagen phase for about 2-6 years. This is the most prolonged phase in the hair cycle. In this phase, the hair is in active growth. This means the hair is continuously growing since the cells in the root of the hair are quickly dividing and producing new cells. About 80% to 90% of hair follicles are in the anagen phase.



Catagen Phase

Hair is in the catagen phase for about 2-4 weeks. In this phase, the hair stops growing and detaches itself from the base of the hair follicle and the blood supply.




Telogen Phase

Hair is in the telogen phase for about 3-5 months. In this phase, the hair follicle is at rest as it prepares for the next hair cycle. Hence, the hair is fully developed in the telogen phase. About 10% through 20% of hair follicles are in the resting phase.




Cycle Starts Over

Soon after the telogen phase once the hair has finished resting, new hair begins to grow to replace the resting hairs which leads the hair to naturally shed.




Hair Structures:

The hair has two different hair structures:


1. Hair Shaft - visible outside of the skin.-

  • The hair shaft is a non-living component of keratinized epithelial cells.

  • Belongs to the cortical layer which determines the strength, texture, and color.

2. Hair Follicle- underneath the surface of the skin.-

  • The hair follicle is a living component that forms the hair bulb

  • Main structure that allows hair to grow


Hair Loss

People who are more prone to experience a lot of hair loss have hormonal changes that cause some people to have a shorter Anagen phase. Which can cause shorter and thinner hair.




Sources:

Image Source: Happy Head


Growth Cycle. (n.d.). Hair Restoration | Hair Again Fresno. Retrieved September 24, 2022, from https://www.fresnohair.com/blog/growth-cycle


Hoover E, Alhajj M, Flores JL. Physiology, Hair. [Updated 2021 Jul 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499948/


Disclaimer: This organization's content is not intended to provide diagnosis, treatment, or medical advice. Content provided on this website is for informational and educational purposes only. Please consult with a physician or other healthcare professional regarding any medical or health-related diagnosis or treatment options. Information on this website should not be considered as a substitute for advice from a healthcare professional.


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