karvakasvua

Karvakasvu, or karvakasvua in its grammatical form, denotes the growth of hair produced by follicles in the skin of mammals, including humans. The process involves hair follicles generating keratinized strands that emerge from the epidermis and project through the skin surface. Hair growth occurs through repeating cycles that include anagen (growth phase), catagen (transitional phase), and telogen (resting phase). Some descriptions also include exogen, the shedding phase. The length and duration of the anagen phase determine the maximum length of hair in a given region. On the scalp, anagen can last several years, while body hair generally has shorter growth periods.

Growth rate and characteristics vary by region and individual. Scalp hair typically grows about 0.3–0.4 millimeters per day (roughly 1 centimeter per month), with growth influenced by age, hormones, nutrition, and genetics. Hair fibers differ in thickness and pigmentation, and follicles produce either vellus hairs (fine and often barely pigmented) or terminal hairs (thicker and usually pigmented).

Regulation of karvakasvu is complex and involves hormonal and genetic factors. Androgens influence the distribution and thickness of terminal hair, while genetics determine baseline density and regional patterns. External factors such as nutrition, illness, medications, and stress can alter growth rate or cycle timing.

Clinical relevance and variation are observed in humans and animals. In humans, patterns of growth and shedding relate to conditions such as hirsutism, androgenetic alopecia, and alopecia areata. In many mammals, hair growth serves functions including insulation, camouflage, and protection, with seasonal shedding in several species.