Question

What are the three phases of the hair growth cycle? What occurs during each phase?

A) Anagen phase: Active growth phase where hair follicles produce new cells.
B) Catagen phase: Transition phase, during which hair growth slows down.
C) Telogen phase: Resting phase where the hair follicle is dormant before shedding.
D) Exogen phase: Shedding phase where old hairs are released and new ones begin to grow.

Answer 1

The hair growth cycle includes three phases: the anagen phase of active growth, the catagen transition phase, and the telogen resting phase, after which the hair is shed and a new cycle begins.

Step-by-step explanation:

Hair Growth Cycle

The hair growth cycle consists of three main phases: the anagen phase, the catagen phase, and the telogen phase. During the anagen phase, which can last from 2 to 7 years, cells divide rapidly at the root of the hair, causing the hair to grow. This is followed by the catagen phase, a brief transitional period lasting 2 to 3 weeks, where the hair growth slows down. The cycle concludes with the telogen phase, a resting phase lasting about 2 to 4 months, after which the hair is shed and a new anagen phase begins, replacing the old hair with new growth.

Hair loss can occur when more hair is shed than what is replaced, a scenario that might be influenced by hormonal changes, dietary factors, aging, or other hormonal influences. Hair growth begins in the follicle with the division of stem cells which produce new keratinocytes, and the basal cells in the hair matrix give rise to both the hair and its sheath. The rate of hair growth during the anagen phase is approximately 0.3 mm per day.