karvankasvysyklien

The term karvankasvysyklien refers to the hair growth cycles that regulate the growth, rest, and shedding of hair follicles. Each hair follicle on the scalp, face, or body undergoes a repeating sequence of growth phases, leading to the continuous renewal of hair. This biological process is governed by genetic, hormonal, and environmental factors that influence the duration and frequency of each phase.

Anagen, the active growth phase, is the longest period of the hair cycle. During anagen, cells in the hair bulb rapidly divide, elongating the hair shaft. The length of the anagen phase determines how long a hair can grow, ranging from a few months for eyebrow hair to several years for scalp hair. The end of anagen is triggered by specific signaling pathways that signal the follicle to transition to the next stage.

Catagen, the transitional phase, lasts only a few weeks. In this phase, hair growth stops as the outer root sheath shrinks and the inner root sheath separates from the matrix cells, forming a club hair. Catagen is mediated by changes in hormones such as dihydrotestosterone and growth factors that modify the cellular environment within the follicle.

Telogen, the resting phase, precedes shedding and lasts about one to three months. During telogen, the follicle stays dormant while the old hair remains attached to the follicle. After telogen ends, the follicle reenters anagen. The proportion of hairs in each phase determines hair density and thickness. Factors such as aging, hormonal imbalances, nutritional deficiencies, and medical conditions can alter these phases, leading to hair thinning or baldness.