Hair Science and Structure Flashcards

Which layer of the hair shaft is responsible for the hair's strength and elasticity?

Answer: Cortex

The cortex makes up the majority of the hair shaft and contains the fibrous proteins (keratin) that give hair its strength, elasticity, and colour.

What is the primary protein that makes up human hair?

Answer: Keratin

Keratin is a tough, fibrous protein that is the primary structural component of hair, nails, and the outer layer of skin.

Which type of melanin produces red and yellow hair colours?

Answer: Pheomelanin

Pheomelanin is the pigment responsible for red and yellow tones in hair. Eumelanin produces brown and black colours.

What chemical bond in hair is broken by water and heat and reforms when hair dries or cools?

Answer: Hydrogen bond

Hydrogen bonds are weak physical bonds that are easily broken by water and heat. They are responsible for temporary styling changes like blow-drying and curling.

During which phase of the hair growth cycle does the hair actively grow?

Answer: Anagen phase

The anagen phase is the active growth phase of hair follicles, lasting 2 to 7 years. Approximately 85-90% of scalp hairs are in this phase at any time.

What is the function of the arrector pili muscle attached to the hair follicle?

Answer: It causes goosebumps by contracting

The arrector pili muscle is a small involuntary muscle attached to the hair follicle. When it contracts, it causes the hair to stand upright, creating goosebumps.