Accessory Structures of the Skin: Hair, Nails, and Glands

Accessory Structures

Include hair, nails, sweat, and sebaceous glands.

Hair Follicle

Epidermal penetration in dermis where hair originates.

Hair Shaft

Part of hair exposed above skin surface.

Hair Root

Anchored part of hair below skin surface.

Hair Bulb

Enlarged base of hair root containing matrix.

Hair Matrix

Layer of mitotically active basal cells.

Hair Papilla

Connective tissue structure with blood capillaries.

Arrector Pili

Smooth muscle causing hair to stand up.

Goosebumps

Visible reaction from arrector pili contraction.

Hair Functions

Includes protection, sensory input, thermoregulation, communication.

Eccrine Sweat Gland

Produces hypotonic sweat for thermoregulation.

Apocrine Sweat Gland

Associated with hair follicles, thicker sweat.

Sebaceous Gland

Oil gland that lubricates skin and hair.

Sebum

Oily secretion that keeps skin pliable.

Nail Bed

Specialized epidermis structure for nail formation.

Nail Body

Protective part of the nail formed on bed.

Nail Root

Base of nail where growth occurs.

Nail Cuticle

Overlapping skin at proximal end of nail.

Lunula

Crescent-shaped region at base of nail.

Hyponychium

Thickened layer beneath the free edge of nail.

Hair Growth Rate

Hair grows approximately 0.3 mm per day.

Hair Loss Rate

Average loss of 50 hairs daily.

Melanin

Pigment responsible for hair color.

Hormonal Influence

Hormones affect hair growth and loss.

Thermoregulation

Process of maintaining body temperature.

Pheromone Response

Biological response to chemical signals in sweat.

Antiperspirants

Use aluminum compounds to block sweat glands.