Scalp hair grows about 1–1.5 cm per month; fingernails about 3–4 mm per month. Toenails grow more slowly at about 1.5 mm per month. Growth slows after age 60.

Hair follicles cycle through anagen (growth, 2–7 years), catagen (transition, 2–3 weeks), telogen (rest/shedding, ~3 months). 85–90% are in anagen; 50–100 hairs shed daily is normal.

A hair follicle is a tiny skin organ that produces hair via stem cells and blood supply. The dermal papilla signals growth; matrix cells make the hair shaft.

Hair stops growing because the anagen phase has a genetically set time limit. When it ends, the hair sheds.

Nails grow from the base, from the nail matrix under the cuticle. Damage to the matrix can cause permanent deformity.

Each body region has a genetically programmed anagen duration. Scalp: years; eyebrows: months. Hormones also affect length.

Color comes from melanin. Gray hair happens when melanocyte stem cells decline with age, stress, or nutrition.

No. It appears longer because skin dehydrates and retracts.

Fingers have better blood flow and more activity, supporting faster matrix growth.

Genetics, nail matrix shape, fingertip bone structure, and age. Vertical ridges are normal with aging.

Thickness depends on the length of the nail matrix (genetic). Longer matrix = thicker nail.

The lunula is the visible part of the nail matrix. It looks white because new cells are not fully transparent.