1. Integumentary System

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

3. 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

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

5. 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

6. 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

7. 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

8. Epidermis Merkel Cells
help provide animals with sensory information from whiskers

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

10. 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

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

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

13. 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

14. 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

15. 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

16. Skin Appendages
Sweat glands
on feet
minor role in cooling

17. 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

18. 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

19. 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