Hair is produced on 90% of the body. It grows from tiny hair follicles imbedded in the surface of the skin. The follicle is cradled in a microscopic sac or hair bulb commonly called the hair root. Hair follicles are alive and produce an outgrowth of cells that form a dead hair strand. Individual follicles can produce as many as 3 stands at one time and in different phases of growth cycles. Follicles have the incredible ability to fully regenerate when pulled out from the hair sac and skin.
Adjacent to the living follicle are sebaceous glands whose primary function is to produce the sebum or natural oil that moisturizes and softens the skin and hair. The production of sebum is determined by factors such as genetics, age, hormones and skin health. Sebum also protects the skin from toxins and damage. Chemicals such as isopropyl alcohol break down this natural barrier.
The only sensation attributed to hair is due to the autonomic and sensory nerves in the skin surrounding the follicle. Each follicle is also enriched with both types of nerve fibers attached to it. Nerve fibers do not live in the outgrowth of hair cells and therefore it is painless to cut, burn, alter or damage hair strands.
A microscopic capillary is attached to each hair bulb/sac. This capillary is how the body feeds the follicle providing essential nutrients to the cells before they harden and produce the horny outgrowth we know as a hair strand. When hair is pulled directly from the hair sac, a tiny, usually microscopic, drop of blood can be released. This normally goes unnoticed even if the whole follicle is removed.
Skin, hair and nails contain an amino acid protein chain we know as alpha keratin. Sulfur, oxygen, hydrogen, nitrogen, carbon and amino acid chains make up the basic building blocks of hairs physiology. Hard keratin forms hair, nails, feathers, horns, talons, claws, hooves and the enamel on teeth. Soft keratin is in skin, internal organs and tissue of animals, amphibians and reptilian bodies.
Keratin is innately insoluble, meaning that it is impossible to dissolve in water and is NOT a dietary protein that can be synthesized by your body. This means your body CANNOT absorb and use keratin to nourish your hair or any other part of your body. Keratin supplements are a gimmick. Keratin is a byproduct of the body's innate ability to synthesize amino acid proteins in blood to fortify cells from minor damage. A healthy diet rich in dietary proteins contained in legumes and meat is the best source of supplementing the bodies ability to produce keratin. Even vegans can get enough protein in their diet to mainitain strong hair and a healthy body.
Ingested keratin such as nails and hair strands can build up in the stomach and block its ability to digest food and can require surgical removal. It's innately very strong and highly resistant to digestive acid. The oldest known existing hair piece is over 2000 years old proving that hair is also very resistant to decay. Do not ingest liquid keratin in beauty products it is toxic.
With all this information and with so much more available about the biology and science of hair, we know that hair is a dead outgrowth of cells, an unfeeling appendage of the skin. Even though dead cells cannot heal you CAN however, TEMPORARILY REPAIR the damage and dryness created by hot water, environmental factors, heating appliances, chemicals treatments, poor nutrition and adverse health issues.