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INTEGUMENTARY SYSTEM. Chapter 5. Cutaneous Membrane superficial epithelium-epidermis underlying connective tissue-dermis underneath the dermis-subcutaneous layer. Accessory structures located in the dermis -hair nails exocrine glands (sebaceous and sweat glands).
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INTEGUMENTARY SYSTEM Chapter 5
Cutaneous Membrane superficial epithelium-epidermis underlying connective tissue-dermis underneath the dermis-subcutaneous layer Accessory structures located in the dermis -hair nails exocrine glands (sebaceous and sweat glands) Components of Integumentary System
Functions of the Skin • Protection-of underlying tissues and organs • Excretion-of salts, water and organic wastes • Maintenance of normal body temperature • Synthesis of Vitamin D3 • Storage of nutrients • Sensory function-detection of touch, pressure, pain and temperature.
EPIDERMIS • Provides mechanical protection. • Helps keep microorganisms outside the body. • Layer consists of stratified squamous epithelium. • The most abundant epithelial cells, the keratinocytes form different layers. • Thick skin (5) and thin skin (4)-refer only to the epidermis.
EPIDERMAL LAYERS • Stratum Germinativum (basale) • Stratum Spinosum • Stratum Granulosum • Stratum Lucidum • Stratum Corneum
Stratum Germinativum • This layer is firmly attached to the basement membrane. • Epidermal Ridges • Most of the cells are keratinocytes. • Stem cells divide and replace with the cells on top (keratinocytes) • these cells are also nourished by the adjoining tissues in the dermal layer. • The accessories arise from this layer.
Stratum Spinosum • This consists of 8-10 layers of cells • Also contain Langerhans cells, part of the immune system (defense against microorganisms and cancers). • Cannot be distinguished in standard histological procedures.
Stratum Granulosum • This is also called the grainy layer. • Contains 3-5 layers of keratinocytes. • Manufacture keratohyalin and keratin. • Keratin is the basic component of hair and nails.
Stratum Lucidum • In the thick skin of the palms and soles. • Cells in this layer are flattened, densely packed and filled with keratin.
Stratum Corneum • These contain 15-30 layers of keratinized cells. • This layer is water-resistans but not waterproof. • Takes 15-30 days to move from base to top. • Coated with lipid secretions from sebaceous and sweat glands. • Insensible vs.sensible persipiration. • Xerosis
Skin Pigmentation • Interaction between pigment composition and concentration and the dermal blood supply. • Pigments are melanin and carotene. • Melanocytes secrete melanin. Amount of pigment varies. • Melanin is produced from the amino acid tyrosine.
Skin Pigmentation • Carotene, a yellow orange pigment is a precursor of vitamin A. This is found in the stratum corneum and fatty areas of the dermis and subcutaneous layer. • Melanin protects against UV damage. • Albinism is an inherited disorder, where the individual is unable to produce melanin. • Vitiligo, irregular white spots.
Dermal Circulation • Red blood cells contain hemoglobin. • When bound to oxygen-bright red color • when oxygen is removed-darker red tone. Seen from surface a bluish coloration called cyanosis. • Also response to respiratory or circulatory disorders.
DERMIS • Pappilary layer -consists of loose connective tissue, capillaries and neurons. • reticular layer - dense irregular connective tissue. • Accessory organs of epidermal origin, such as hair follicles and sweat glands extend into the dermis. • Sensory receptors_ Meissner’s and Pacinian
Accessory StructuresHair • Anatomy of hair • Hair Growth • Hair color • Hair functions-protection from UV light, cushion a blow and insulate the head, prevent entry of foreign materilas. • Arrector pilli muscle. • Types of hair-velllus and terminal
Accessory StructuresGlands • Sebaceous Glands- holocrine, secrete sebum. Provides lubrication and inhibits growth of bacteria. • Sudoriferous Glands (sweat glands)-apocrine or merocrine. Coolong the surface of skin, excretion and protection. • Mammary Glands- • Ceruminous Glands
Accessory StructuresNails • Anatomy of the nail-consists of dead, tightly compressed cells packed with keratin. • Function of the nail
Injury and Repair • Scab • Granulation Tissue • Scar Tissue • Keloid
Aging and the Integumentary System • Epidermis thins • Langerhans cells decrease • Vitamin D production decreases • Melanocyte activity declines • Glandular activity declines • Blood supply to dermis is reduced • Dermis thins