Hair is composed of keratin, which is a strong fibrous protein, and is built from cells similar to skin cells. The number of hairs on a human scalp on average would be around 100,000 – 120,000, this varies depending on the type of hair you have, with redheads having less and blondes generally have more.
Each person is born with a set amount of hair follicles. Hair grows from the follicles that enclose the hair root in the person’s scalp. Hair normally grows at a rate of around 1.25cm or 0.5 inches per month and around 6 inches per year. A healthy hair can stretch up to 30% of its length and can absorb its weight in water.
HAIR CHEMICAL COMPOSITION
The hair itself is composed of 28% protein, around 2% lipid and 70% water, with the most abundant protein being keratin. Keratin consists of polypeptide chains rich in cysteine.
The main elements are:
Carbon (c) with 45%, Oxygen (O) with 30%, Nitrigen (N) with 15%, Hydrogen (H) with 6% and Sulfur (S) with 5%.
There is also Calcium (Ca), Copper (Cu), Cadmium (Cd), Mercury (Hg), Zinc (Zn), Lead (Pb), Iron (Fe), Arsenic (As), Silicon (Si), Magnesium (Mg), Uranium (U), Vanadium (V), Sodium (Na) and Potassium (K).