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