Hair Science and Structure Flashcards

What is the outermost layer of the hair shaft called?

Answer: Cuticle

The cuticle is the outermost protective layer of the hair shaft, consisting of overlapping scales that protect the inner cortex from damage.

Which bond in the hair is the strongest and can only be broken by chemical treatments?

Answer: Disulfide bond

Disulfide bonds are strong covalent bonds formed between sulfur atoms of cysteine amino acids. They can only be broken by chemical processes such as perming or relaxing.

What does the pH scale measure?

Answer: Acidity or alkalinity of a solution

The pH scale measures the acidity or alkalinity of a solution on a scale from 0 to 14, with 7 being neutral. Hair and skin have a natural pH of approximately 4.5 to 5.5.

What is the approximate natural pH of healthy hair and skin?

Answer: 4.5 to 5.5

Healthy hair and skin have a natural pH of approximately 4.5 to 5.5, which is slightly acidic. This is often referred to as the acid mantle.

The telogen phase of the hair growth cycle is best described as what?

Answer: The resting and shedding phase

The telogen phase is the resting phase lasting about 3 to 4 months, during which the hair follicle is at rest and the old hair is eventually shed to make room for new growth.

What structure at the base of the hair follicle provides nourishment for hair growth?

Answer: Dermal papilla

The dermal papilla is a small, cone-shaped structure at the base of the follicle that contains blood vessels and nerves. It supplies nutrients essential for hair growth.