Integumentary System

Integumentary System Skin and its appendages Largest and most visible organ of the body Distinct regions Epidermis Basement Membrane Zone Dermis Subcutis/Hypodermis

Integumentary System Functions: Enclosing barrier preventing the loss of water, electrolytes, and cells Protection from the environment Allowing motion Temperature regulation Storage Pigmentation Immunosurveillance Production of vitamin D Sensory perception Excretory secretions

Epidermis outer layer provides protection from foreign substances composed of several cells: Keratinocytes Melanocytes Langerhans cells Merkel cells

Epidermis Keratinocytes provide a protective layer constantly being renewed (keratinization) new skin cells are created near the base of the epidermis and migrate upwards, producing a compact layer of dead cells on the skin surface keeps in fluids, salts, and nutrients keeps out infectious or foreign agents

Epidermis Melanocytes located at base of epidermis, outer root sheath of hairs, and ducts of sebaceous and sweat glands produce melanin (pigment) helps protect cells from UV radiation

Epidermis Langerhans Cells part of immune system damaged when exposed to excessive UV light and glucocorticoids (anti-inflammatory drugs) play an important role in the skin's response to foreign substances Ex: rash development if animal is exposed to an irritant

Epidermis Merkel Cells help provide animals with sensory information from whiskers

Basement Membrane Zone located at the base of the epidermis, connecting it to the dermis protective barrier between the epidermis and the dermis

Dermis supports and nourishes the epidermis and skin appendages (via blood vessels) blood vessels also regulate skin and body temperature sensory nerves are located in the dermis and hair follicles secretes proteins: collagen and elastin give support and elasticity immune cells defend against infectious agents

Subcutis/Hypodermis innermost layer contains subcutaneous fat and muscles fat provides: Insulation reservoir for fluids, electrolytes, and energy shock absorber

Skin Appendages hair follicles, oil and sweat glands, and claws grow out of the epidermis and dermis

Skin Appendages hair follicles cats and dogs are compound follicles have a central hair surrounded by 3 to 15 smaller secondary hairs all exiting from one pore born with simple hair follicles that develop into compound hair follicles. growth of hair is affected by nutrition, hormones, and change of season size, shape, and length of hair are controlled by genetics and hormones

Skin Appendages coat protects the skin from physical and UV light damage coat helps regulate body temperature trapping dead air space between secondary hairs conserves heat cold-weather coat is longer and finer to facilitate heat conservation coat can also help cool the skin warm-weather coat has shorter, thicker hairs and fewer secondary hairs anatomic change allows air to move easily through the coat

Skin Appendages Oil Glands (sebaceous glands) Sebum secrete sebum into the hair follicles and skin present in large numbers near the paws, back of the neck, rump, chin, and tail area Sebum mixture of fatty acids keeps skin soft, moist, and pliable Makes coat look shiny has antibiotic properties

Skin Appendages Sweat glands on feet minor role in cooling

Hereditary Hair Loss (Alopecia) born totally or partially without hair hairlessness can also develop with age can be associated with abnormal teeth, claws, and eyes, or with skeletal and other developmental defects prone to hair follicle infections and inflammation caused by foreign objects

Albinism always associated with pink or pale irises visual defects and increased risk of skin damage from sunlight some animals with extreme piebaldism (spotted or blotched with black and white) or dominant white have associated nervous system abnormalities or deafness in one or both ears

Ringworm infection of skin, hair, or claws caused by a dermatophyte (fungus); ZOONOTIC develop circular, bald, scaly patches with broken hairs in ring-like whirls common areas: face, ear tips, tail, & feet Diagnosis: fungal culture, UV lamp, and skin scraping (microscope) Treatment: antifungal medications, medicated shampoos, isolation, disinfect all fomites