Integumentary system And its appendages!

Membranes Thin, sheetlike structure Lines and protects body surface, body cavities and organs Some secrete lubricating fluids to decrease fluids.

Membranes 2 major categories  Epithelial Made of epithelial and underlying connective tissue  Connective Exclusively connective

Epithelial Membranes 3 types  Cutaneous  Serous  mucous

Cutaneous Membrane Skin Approximately 16% of body weight

Serous membrane Only on surfaces within closed cavities Thin layer of simple squamous epithelium basement membrane – connective tissue that holds and supports the epithelial tissue

Types of serous membranes Parietal portion – lines cavity Visceral portion – lines organs Thoracic cavity – Pleura  Parietal pleura  Visceral pleura Abdominal cavity – Peritoneum  Parietal peritoneum  Visceral peritoneum

Serous membrane conditions Serous membranes secrete a thin watery fluid to help with friction. Pleurisy – condition characterized by inflammation of membrane that line the thoracic cavity and lungs Peritonitis- inflammation of serous membrane in abdominal cavity

Mucous membranes Line body surface openings (to exterior)  Respiratory, digestive, urinary and reproductive tracts Secrete thick, slimy material (mucus) Mucocutaneous junction – area that skin and mucous membranes meet.  Lack accessory organs (hair, glands)  Eyelids, nasal openings, vulva, anus  Sites of common infections/irratiations

The Skin 1 square inch of skin contains  500 sweat glands  1000 nerve endings  Yards of tiny blood vessels  100 sebaceous glands  150 sensors for pressure  75 sensors for heat, 10 for cold  Millions of cells

Structure of skin Epidermis – outermost, stratified squamous Dermis – mostly connective tissue Subcutanous – hypodermis – loose connective tissue and fat (insulation, stored energy)

Epidermis Stratum germinativum  Undergo mitosis and reproduce – skin can repair itself  As new layers form, old move upward and slough off.  Pigment layer – melanin, melanocytes Stratum corneum – tough outer layer (keratin)

Variations in skin  Cyanosis – skin is bluish grey, lack of blood flow  Vitiligo – areas of loss of epidermal melanocytes  Albinism – partial or total lack of melanin  Pregnancy mask – blotchy pigmented areas of brown pigmentation  Freckle – flat macule, genetic in light skin people  Age spots – flat pigmented lesions  Blisters – when specialized junctions between cells are weakened or destroyed.

Dermis Cells are scattered apart with fibers in between (collagen and elastic) Dermal papillae – parallel row of peglike projections (fingerprinting) Stores specialized nerves for pressure, pain, temperature

Variations in dermis Striae – stretch marks As we age – elastic fibers lessen, amount of fat stored in hypodermis lessens = wrinkles Strawberry hemangioma – malformation of dermal blood vessels (birthmarks) Port wine stain – permanent, pigmented vascular birthmark Stork bite – dilation of dermal capillaries

Appendages - Hair Lanugo – hair of newborn, soft, fine Hairless – lips, palms of hands, soles of feet Hair follicle – tube where hair grows from hair papilla in dermis Hair shaft – visible hair Living hair papilla = growth Alopecia – hair loss  Male pattern baldness – inherited Arrector pili muscle – goose bumps – attached to dermal papilla and hair follicle

Receptors Pacinian corpuscle – deep in dermis, detects pressures Meissner’s corpuscle – superficial in dermis, detects light touch

Nails Produced by cells of epidermis Epidermal cells fill with keratin and become hard Cuticle – fold of skin at base of nail Lunula – nail body nearest root, little moon Nail bed – under nail, pink because vascular Onycholysis – lossof nail due to trauma

Skin glands Sweat (sudoriferous) glands  Eccrine – transparent watery liquid, sweat  Apocrine – larger and secrete thicker, milky secretion, odor due to contamination and decomposition of the secretion by skin bacteria. Sebaceous – oil for hair and skin  Secretion – sebum  Increase during puberty – pimples  Acne = papules (inflamed lesions), pustules (pus filled pimples

Functions of skin Protection Temperature regulation Sense organ activity