Chapter 5 Integument Skin

Skin-Characteristics Largest organ in the body Weighs about 10 pounds Covers the entire body

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Layers of the Integument Epidermis- outer layer Dermis-under the epidermis Hypodermis-not part of skin; skin attached to it

The saying “beauty is only skin deep” is only pertinent to the __________ layer, which is outwardly visible. epidermal dermal hypodermal integumentary Answer: a. epidermal

Epidermis Keratinized Stratified Squamous Epithelium Cell Types-Keratinocytes (most abundant) - Melanocytes (produce melanin which protect against UV radiation; tanning - Merkel cells-sensory receptor for touch - Langerhans- macrophages

Layers of Epidermis Basale-bottom; location of melanocytes/Merkel cells Spinosum-several cells thick; location of Langerhans cells Granulosum-keratohyaline granules (keratin)/ Lamellated granules (waterproofing glycolipid)

Layers of Epidermis (con’t) Lucidum-visible only in thick skin Corneum- 20 to 30 cell layers thick; outermost layer; most of the thickness of the epidermis All the cells in these layers are dead

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A patient taking a drug that inhibits cell division (such as certain chemotherapy drugs) would expect which layer of the epidermis to be most noticeably affected? Stratum corneum Stratum lucidum Stratum spinosum Stratum basale Answer: d. Stratum basale

Dermis Strong, flexible connective tissue Rich supply vessels, nerve fibers Contains hair follicles, oil, and sweat glands which are derived from the epidermis but seen in the dermis Contains Pacinian Corpuscles that respond to deep touch

Layers of the Dermis Papillary Layer Reticular Layer

Papillary Layer Areolar Connective Tissue Dermal papillae  folds of tissue Meissner’s Corpuscles (Light touch receptors) part of what makes fingerprints

Reticular Layer Dense Irregular Connective Tissue contain cleavage and flexure lines contain the collagen that gives skin strength/resilience

Homeostatic Imbalance Striae  stretch marks

Skin Color Melanin- the more that is produced the darker the skin Carotene-yellow/orange pigment in plants Hemoglobin- causes the pink color of fair skin when well oxygenated

Homeostatic Imbalance Cyanosis  appear blue, poorly oxygenated blood Jaundice  yellow cast, bilirubin build up

Sweat Glands Eccrine Sweat Glands (Merocrine)- most numerous; found all over but most on palms, soles, forehead; produce sweat Apocrine Glands- axillary/ano-genital area Ceruminous-ear; cerumen (ear wax) Mammary Glands-produce milk

Sebaceous Glands (Oil) Found everywhere except palms/soles secrete sebum holocrine secreting blockage causes acne associated with hair follicle

Homeostatic Imbalance Acne  infected sebaceous gland Whitehead, Blackhead Seborrhea  cradle cap

One critical function of sebum, in addition to roles in waterproofing and skin softening, is that it provides protection against ____________. overexposure to the sun overheating harmful bacteria abrasions or cuts to the skin Answer: c. harmful bacteria

Nails Covers distal ends of fingers/toes Contains hard keratin Matrix is responsible for nail growth

Hair Located everywhere except palms, soles, lips, nipples, and parts of genitalia Contains 3 layers Medulla-inner layer Cortex- surrounds the medulla Cuticle-outer layer; single layer of cells; arranged like shingles

Hair Follicle Usually found in the dermis Hair matrix in the bulb produces the hair Associated with arrector pili-smooth muscle that will pull hair straight up with cold/anxiety

Functions of Integument Protection Chemical Barriers- acid mantle; melanin Physical Barriers- keratin, water proofing glycolipid Biological Barriers- Langerhans cells

Functions of Integument (con’t) Cutaneous Sensation-sensors that are part of the nervous system Meissner’s Corpuscles/ Merkel’s Discs- light touch Pacinian Corpuscles- deep pressure

Functions of Integument (con’t) Metabolic Functions- convert inactive Vitamin D to active Vitamin D Blood Reservoir- ~ 5% of total blood volume Excretion- very small amount of nitrogenous waste; large amounts of salt and water

Skin Cancer Basal Cell Carcinoma-starts in basale cell layer; almost always curable Squamous Cell Carcinoma- starts in the spinosum layer; almost always curable Melanoma- starts in melanocytes; > 4 mm and chance of cure almost zero; deadliest form of cancer

Use at least 30 sun block both for UVA and UVB rays Stay out of Sun!!!! Use at least 30 sun block both for UVA and UVB rays

No tanning booths!

Burns First Degree Burn- red, painful, only epidermis Second Degree Burn- red, blistered, epidermis and upper dermis Third Degree Burn- gray white, ashen, cherry red; all layers involved

Rule of Nines Used to determine the percentage of body covered in burns