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