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Explore the integumentary system focusing on the skin and its accessory structures, including the layers of the skin, membranes, cell types, and skin color pigments. Learn about the functions of hair, glands, and the effects of burns on skin health. Enhance your knowledge of the integumentary system for a better understanding of homeostasis and skin disorders.
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Chapter 5The Integumentary System • Skin and its accessory structures • structure • function • growth and repair • development • aging • disorders
General Anatomy • A large organ composed of all 4 tissue types • 22 square feet • 1-2 mm thick • Weight 10 lbs.
Function of Integumentary system • 4 functions:
Focus on Homeostasis • What happens to a burn patient
Overview • 2 Major layers of skin • epidermis is epithelial tissue only • dermis is layer of connective tissue, nerve & muscle • Subcutaneous tissue (subQ or hypodermis) is layer of adipose & areolar tissue • subQ = subcutaneous injection • intradermal = within the skin layer
Membranes • Epithelial layer sitting on a thin layer of connective tissue (lamina propria) • Types of membranes • mucous membrane • serous membrane • synovial membrane • cutaneous membrane (skin)
Mucous Membranes • Lines a body cavity that opens to the outside • mouth, vagina, anus etc • Epithelial cells form a barrier to microbes • Tight junctions between cells • Mucous is secreted from underlying glands to keep surface moist
Serous Membranes • Simple squamous cells overlying loose CT layer • Squamous cells secrete slippery fluid • Lines a body cavity that does not open to the outside such as chest or abdominal cavity • Examples • pleura, peritoneum and pericardium • membrane on walls of cavity = parietal layer • membrane over organs in cavity = visceral layer
Synovial Membranes • Line joint cavities of all freely movable joints • No epithelial cells---just special cells that secrete slippery fluid
Overview of Epidermis • Stratified squamous epithelium • Contains no blood vessels • 4 types of cells • 5 distinct strata (layers) of cells
Cell types of the Epidermis • Keratinocytes--90% • produce keratin • Melanocytes-----8 % • produces melanin pigment • melanin transferred to other cells with long cell processes • Langerhan cells • from bone marrow • provide immunity • Merkel cells • in deepest layer • form touch receptor with sensory neuron
Dermis • Connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages & fat cells • Contains hair follicles, glands, nerves & blood vessels • Major regions of dermis(FYI) • papillary region • reticular region
Skin Color Pigments (1) • Melanin produced in epidermis by melanocytes • same number of melanocytes in everyone, but differing amounts of pigment produced • results vary from yellow to tan to black color • melanocytes convert tyrosine to melanin • UV in sunlight increases melanin production • Clinical observations • freckles or liver spots = melanocytes in a patch • albinism = inherited lack of tyrosinase; no pigment • vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches
Accessory Structures of Skin • Epidermal derivatives • Cells sink inward during development to form: • hair • oil glands • sweat glands • nails
Structure of Hair • Shaft -- visible • Root -- below the surface • Follicle surrounds root • external root sheath • internal root sheath • base of follicle is bulb • blood vessels • germinal cell layer
Hair Color • Result of melanin produced in melanocytes in hair bulb • Dark hair contains true melanin • Blond and red hair contain melanin with iron and sulfur added • Graying hair is result of decline in melanin production • White hair has air bubbles in the medullary shaft
Functions ofHair • Prevents heat loss • Decreases sunburn • Eyelashes help protect eyes • Touch receptors (hair root plexus) senses light touch
Glands of the Skin • Specialized exocrine glands found in dermis • Sebaceous (oil) glands • Sudiferous (sweat) glands • Ceruminous (wax) glands • Mammary (milk) glands
Sebaceous (oil) glands • Secretory portion in the dermis • Most open onto hair shafts • Sebum • combination of cholesterol, proteins, fats & salts • keeps hair and skin from soft & pliable • inhibits growth of bacteria & fungi(ringworm) • Acne • bacterial inflammation of glands • secretions stimulated by hormones at puberty
Sudoriferous (sweat) glands • Eccrine (sweat) glands • most areas of skin • secretory portion in dermis with duct to surface • regulate body temperature with perspiration • Apocrine (sweat) glands • armpit and pubic region • secretory portion in dermis with duct that opens onto hair follicle • secretions more viscous
Burns • Tissue damage caused by excessive heat, electrical,radioactive or chemical substances • Destroys skin cells • 1st degree –sunburn(epidermis) • 2nd degree-blisters (epiderm, dermis) • 3rd degree- full thickness- all three layers (epi, dermis and sub cut)
Homework –chapter 5 • Wordbytes • A1 (diagram), A2,A4,A5,A6,A13 • B2, B8,B9, C1,C2,C3,C4 • Focus on Homeostasis, pg, 167 • Look up the disease Systemic lupus erythematosus in your text. What happens in this disease?