Follikulaarit

Follikulaarit, scientifically known as hair follicles, are specialized structures in the epidermis of mammals, including humans, responsible for growing hair. Each follicle is a complex organ composed of various cell types and tissues that work together in a cyclical process of growth, rest, and shedding.

The primary function of a hair follicle is to produce keratin, a tough structural protein that forms hair shafts. This process begins in the bulb of the follicle, where actively dividing cells, called matrix cells, surround a dermal papilla, a small cone of connective tissue that provides nutrients and signals for hair growth. As these cells multiply and differentiate, they are pushed upward and keratinize, forming the hair shaft that emerges from the skin's surface.

Hair follicles are also associated with sebaceous glands, which secrete sebum, an oily substance that lubricates the hair and skin, and arrector pili muscles, small muscles that contract to cause hair to stand on end, a phenomenon known as goosebumps. The activity of hair follicles is influenced by hormones, genetics, and various environmental factors. The hair growth cycle, which includes anagen (growth phase), catagen (transitional phase), and telogen (resting phase), determines the length and duration of hair on different parts of the body. Disruptions to this cycle can lead to conditions like alopecia, or hair loss.