The Integumentary System Chapter 6

Membranes All derived from epithelial or connective tissue Epithelial membranes Line exposed cavities Line organs Secrete serous fluid lubricate

Mucous Membranes Line cavities and tubes exposed to outside Secrete mucus Line respiratory, digestive, urinary and reproductive tracts

Serous Membranes Line joint cavities and covers organs Secrete serous fluid (synovial fluid in joint cavities)

Cutaneous Membranes Covers body surfaces exposed to external environment Dry membrane Skin

Protects from water loss, foreign invasion Maintains body temp. Integumentary System Function Protects from water loss, foreign invasion Maintains body temp. Excretes water, salt, nitrogenous wastes

Sensory organ Produces vitamin D Limited absorption regenerative

Structure – 2 major layers; Epidermis & Dermis Epidermis – 5 layers named for their appearance; produce melanin and carotene to give skin color Stratum corneum – top layer; as cells die they become keratinized (“cornified”); scalelike with no nucleus

Stratum lucidum – several rows of clear flat cells; found only on skin of palms and soles Stratum granulosum – 3 – 5 layers of flattened cells; transition layer

Stratum spinosum – 8-10 layers of polyhedral cells Stratum basale (germinativum) – single layer of cuboidal or columnar cells that are constantly dividing; accelerated by friction or pressure

Dermis – below epidermis; thicker Has many upward projections (dermal papillae) Binds epidermis to underlying tissue Composed of collagen and elastic fibers in a gooey matrix

Provides strength and elasticity Vascular; bed sores are a problem here. Innervated (sensory and motor – for arrector pili muscles) Divided into 2 regions Papillary – upper Reticular - lower

Reticular layer contains accessory organs: Hair follicles Sebaceous glands Arrector pili muscles Sudoriferous glands

Blood vessels Nerves Attaches dermis to bone & muscle by way of subcutanous layer (adipose tissue)

Hair Formed by epidermal cells at base of follicle; growth due to division of cells in base of follicle = root As cells die; they keratinize

Glands A) Merocrine – fluid B) Apocrine – pts of cells & fluid C) Holocrine – whole cell rlsd & disintegrates

Sebaceous glands Sebum – produced in cytoplasm of cell and is discharged when cell dies (holocrine gland) Secreted into hair follicles; helps keep hair and skin soft and pliable.

Sudoriferous glands Armpits/hair; triggered by stress (apocrine glands) Forehead, neck, back; triggered by temp. (merocrine glands)

Nails Produced by epithelial cells at root Nail bed Lanula – highly mitotic Keratinization – harder than other keratin

Skin Pathology Burns – evaluated by degree; each degree is deeper into the skin Danger of burns is infection and dehydration Rule of nines – body is broken into 9 sections; % of burned area is determined by how many of these parts are affected.

1o burn Erythema of the skin Top layers of epidermis affected

2o burn Erythema and blistering Epidermis and dermis affected

3o burn – most serious Charred, or white appearance Epidermis, dermis and subcutaneous tissue burned Skin grafts needed Critical Pain is minimal after burn until nerves begin to regenerate Hair usually does not grow back

Skin Colorations Albinism Vitiligo Freckles Mongolian spots Cyanosis Jaundice Hemangioma Erythema nevi

Skin Eruptions (contact dermatitis) Urticaria - hives Insect bites blisters

Lesions Viral – cold sores, “pox”, genital warts Bacterial – chankers, Impetigo, boils, carbuncles Fungal – moniliasis, Tinea pedis, ringworm Ulcerative - bedsores

Growths Warts - viral Corns – pressure on skin of feet Callus – pressure on skin

Sebacceous Glands Whiteheads Acne Seborrhea Blackheads Psoriasis eczema

Seborrhea Eczema Psoriasis

Alopecia – nongenetic hair loss Wrinkles – loss of collagen and elastic fibers Scarring – growth of connective tissue above epithelial tissue; genetically determined

Stretch marks – growth of connective tissue due to rapid stretching of skin; genetically determined