Describe the structure of a hair. What causes goose bumps?

Structure of a Hair

A hair consists of three main components: the cuticle, the cortex, and the medulla.

* Cuticle: The cuticle is the outermost layer of the hair and is made up of tightly packed scales that protect the inner layers of the hair from damage.

* Cortex: The cortex is the middle layer of the hair and is responsible for the hair's strength and elasticity. It contains keratin, a type of protein that is also found in nails and skin.

* Medulla: The medulla is the innermost layer of the hair and is made up of loosely arranged cells. It is not present in all hair types.

Goose Bumps

Goose bumps, also known as piloerection, are caused by the contraction of small muscles at the base of each hair follicle. When these muscles contract, they pull the hair shaft up, causing the skin around the hair follicle to rise and form a small bump.

Goose bumps are a natural reflex that is triggered by cold temperatures, fear, or excitement. When the body is cold, the blood vessels in the skin constrict in order to conserve heat. This causes the skin to become pale and cool, and the hair follicles to contract, producing goose bumps. Goose bumps can also be triggered by fear or excitement. In these cases, the body releases hormones such as adrenaline and cortisol, which cause the hair follicles to contract.

Goose bumps are a harmless reflex that do not typically cause any problems. However, in some cases, they can be associated with medical conditions such as hypothyroidism or anorexia nervosa. If you are concerned about your goose bumps, talk to your doctor.