Epidermis, Dermis, and Subcutaneous Layer

Subcutaneous Layer

Fatty tissue providing insulation and padding

Hair

Filamentous structure originating from the epidermis, providing insulation, protection, sensory input, and communication

Protection

Function of hair physically protecting the skin from UV rays, abrasions, etc.

Insulation

Function of hair providing warmth through underfur and arrector pili muscle

Secondary Sexual Character

Function of hair supporting male/male competition and female choice

Communication

Function of hair to interact with the immediate surroundings

Sensory

Function of hair to sense the immediate surroundings

Bristles

Long hairs often used for visual signals (e.g., lion's mane)

Wool

Long, soft, and usually curly hair

Guard hairs

Longer, often coarse hairs that complement underfur

Epidermis

Outer layer of dead keratinized cells

Mammary glands

Specialized epidermal glands in females that produce milk

Spines

Stiff and enlarged guard hairs (e.g., porcupines)

Dermis

Connective tissue with blood vessels and nerves

Sebaceous glands

Glands associated with hair follicles that secrete oily products

Eccrine glands

Glands not associated with hair that secrete watery secretions to help cool through evaporation

Apocrine glands

Glands that produce viscous fluids acting as chemical signals (pheromones)

Eumelanin

Hair pigment that produces shades of black or brown

Pheomelanin

Hair pigment that produces shades of red or yellow

Angora

Hair that grows continuously to produce long shafts, may or may not be shed

Definitive

Hair that grows to a fixed length then falls out (e.g., single coated dogs)

Scent glands

Modified sebaceous or apocrine glands that use pheromones for communication signals

Vibrissae

Sensory 'whiskers' that are long and stiff

Forensics

The use of scale patterns in hair for identification purposes