Functions and Structures of Animal Skin

Integumentary system

Includes skin, hair, nails, and glands.

Skin

Largest organ, 12% to 24% body weight.

Vitamin D production

Skin synthesizes vitamin D via sunlight.

Homeostasis

Maintains stable body conditions.

Barrier function

Protects from dehydration and harmful substances.

Protective function

Waterproof shield against UV and injuries.

Immune defense

Contains immune cells to fight infections.

Sensory function

Detects touch, pain, temperature, and pressure.

Exocrine function

Glands secrete sweat, sebum, and wax.

Epidermis

Outer skin layer, no blood vessels.

Dermis

Inner skin layer with connective tissue.

Subcutaneous tissue

Fat layer providing insulation and cushioning.

Stratum corneum

Outermost epidermis layer, dead keratinized cells.

Stratum lucidum

Thin layer, found in thick skin areas.

Stratum granulosum

Contains keratin and waterproofing lipids.

Stratum spinosum

Upper dermis layer with visible tonofilaments.

Stratum basale

Deepest epidermis layer, mitotically active.

Hair

Keratin structure growing from hair follicles.

Sweat glands

Secrete water and salts for cooling.

Sebaceous glands

Produce sebum to lubricate skin and hair.

Ceruminous glands

Produce earwax to protect eardrum.

Mammary glands

Produce milk for newborn nutrition.

Preen gland

Secretes oil for feather waterproofing.

True horns

Permanent, keratin-covered bone structures.

Antlers

Branching bone structures, shed yearly.

Economic importance

Animal skins used for leather and products.

Rabbit fur

Used for coat linings and accessories.

Kangaroo hide

Commonly used for bullwhips.

Feathers

Used for insulation and ceremonial items.