Arrector Pili

Chapter 7

Trichology

Arrector Pili

Comes from cells in the dermis that attach to the follicle just below the sebaceous gland. This is the muscle that causes the hair to stand on end when a person is scared or cold.

Anagen stage

The active or growing stage of hair, during which time each hair bulb has an attached root sheath.

Albinism

Congenital failure of the skin to produce melanin pigment.

Alopecia

Excessive hair loss.

Androgenetic alopecia

Hair loss caused by a combination of heredity, hormones and age that causes progressive shrinking or miniaturization of certain scalp follicles.

Alopecia areata

Sudden loss of hair in round or irregular patches without display of an inflamed scalp.

Catagen stage

A brief transitional stage of hair growth, when all cell division stops.

Cuticle

The outer covering of the hair shaft.

Cortex

The inside the second layer of the hair fiber (gives hair most of its pigment and strength [elasticity]).

Density

The number of active hair follicles per square inch on the scalp.

Dandruff

Pityriasis; overabundance of epithelial cells that have accumulated on the scalp or fallen to the shoulders.

Effleurage

Light, gliding massage strokes or circular motions made with the palms of the hands or pads of the fingertips; often used to begin and/or end a treatment; used on the face, neck and arms.

Elasticity

Ability of hair to stretch and return to its original shape without breaking.

Eumelanin

Type of melanin that produces brown/black hair color.

Friction

Circular or wringing movement with no gliding used on the scalp or with a facial when less pressure is desired; applied with the fingertips or palms; a way in which the hair cuticle can be damaged by combing and brushing.

Follicle

Cluster of cells in the upper layer of the skin; the cell cluster pulls the upper layer down with it, creating a tubelike pocket called the root sheath, out of which the hair will grow.

Keratization

The process whereby cells change their shape, dry out and form keratin protein; once keratinized, the cells that form the hair fiber or strand are no longer alive.

Lice

Parasitic insects transmitted directly from one person to another, or by contact with articles that have come in contact with an infested person (such as combs and brushes, etc.).

Medulla

Central core of the hair shaft, also called the pith (often absent in fine or very fine hair).

Melanin

A pigment that gives skin and hair their color.

Pheomelanin

Type of melanin that produces red hair color.

Petrissage

Light or heavy kneading and rolling of the muscles; performed by kneading muscles between the thumb and fingers or by pressing the palm of the hand firmly over the muscles, then grasping and squeezing with the heel of the hand and fingers; generally perfo

Porosity

Refers to the ability of the hair to absorb moisture, liquids or chemicals.

Postpartum alopecia

The temporary hair loss at the conclusion of pregnancy.

Psoriasis

Round, dry patches of skin, covered with rough, silvery scales; condition is chronic and not contagious.

Ringworm

A highly contagious, fungal infection of the skin or scalp.

Scabies

Medical term for itch mite; red and watery vesicles or pus-filled areas caused by an animal parasite.

Telogen stage

The resting stage of hair growth when each bulb has no attached root sheath, at which time hair falls out; eventually, cell division is again stimulated, producing new hair, and the growth cycle starts again.

Trichology

Study of hair

Vellus

Hair that covers most of the body, including the head; often not visible to the naked eye.