THE INTEGUMENTARY SYSTEM OVERVIEW Integumentary System – consists of the skin and its accessory Skin and subcutaneous tissue organs hair, nails, and cutaneous glands functions of the skin Most visible system and more attention paid to this organ epidermis and dermis system hypodermis Inspp,,gpection of the skin, hair, and nails is significant part of a thick and thin skin physical exam skin color Skin is the most vulnerable organ skin markings exposed to radiation, trauma, infection, and injurious chemicals Hair and nails Receives more medical treatment than any other organ system Cutaneous glands Dermatology – scientific study and medical treatment of the Skin disorders integumentary system 6-1 6-2 SKIN AND SUBCUTANEOUS TISSUE FUNCTIONS OF THE SKIN Resistance to trauma and infection Sensation The body’s largest and heaviest organ keratin skin is our most extensive sense 2 covers area of 1.5 -2.0 m acid mantle organ 15 % of body weight Other barrier functions Thermoregulation Consists of two layers: thermoreceptors epidermis – stratified squamous waterproofing epithelium UV radiation vasoconstriction / vasodilation dermis – connective tissue layer harmful chemicals Nonverbal communication Hypodermis – another connective Vitamin D synthesis acne, birthmark, or scar tissue layer below the dermis Hairs skin first step Transdermal absorption MtMost skin is 1 – 2 mm thic k Sweat pores Dermal papilla Tactile corpuscle Epidermis liver and kidneys complete administration of certain drugs Ranges from 0.5 mm on eyelids to 6 (touch receptor) steadily through thin skin – mm between shoulder blades Blood capillaries process Hair follicle Dermis adhesive patches Sebaceous gland Thick skin – on palms and sole, and Hair receptor corresponding surfaces on fingers and Apocrine sweat gland Copyright © The McGraw-Hill Companies, Inc. 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Hair bulb Hypodermis toes (subcutaneous fat has sweat glands, but no hair follicles Sensory Merocrine sweat or sebaceous (oil) glands nerve fibers gland Piloerector muscle Cutaneous blood vessels epidermis 0.5 mm thick Lamellar (pacinian) corpuscle (pressure receptor) Motor nerve fibers Thin skin – covers rest of the body epidermis about 0.1 mm thick possesses hair follicles, sebaceous glands and sweat glands (a) (b) 6-3 6-4 EPIDERMIS AND CELL TYPES CELL TYPES AND LAYERS OF THE OF THE EPIDERMIS Epidermis – keratinized stratified squamous Sweat pore Stratum corneum Exfoliating Stratum lucidum epithelium keratinocytes Stratum granulosum Dead keratinocytes Five types of cells of the epidermis Sweat duct stem cells Living keratinocytes undifferentiated cells that give rise to keratinocytes Dendritic cell in deepest layer of epidermis (stratum basale) Stratum spinosum keratinocytes Tactile cell great majority of epidermal cells synthesize keratin Melanocyte melanocytes occur only in stratum basale Stem cell synthesize pigment melanin that shields DNA from UV radiation Stratum basale branched processes that spread among keratinocytes Dermal papilla tactile (merkel) cells in basal layer of epidermis Tactile nerve fiber touch receptor cells associated with dermal nerve fibers dendritic (Langerhans) cells Dermis Dermal blood vessels macrophages originating in bone marrow that guard against pathogens found in stratum spinosum and granulosum stand guard against toxins, microbes, and other pathogens that penetrate skin 6-5 6-6 1 STRATUM BASALE STRATUM SPINOSUM Consists of several layers of keratinocytes A single layer of cuboidal to low columnar stem cells and Thickest stratum in most skin in thick skin, exceeded by stratum keratinocytes resting on the corneum basement membrane Deepest cells remain capable of melanocytes and tactile cells are scattered among the stem mitosis cells and keratinocytes cease dividing as they are pushed upward Produce more and more keratin filaments which causes cell to flatten Stem cells of stratum basale higher up in this stratum, the flatter the divide cells appear give rise to keratinocytes that Dendritic cells found throughout this migrate toward skin surface stratum replace lost epidermal cells Named for artificial appearance created in histological section numerous desmosomes and cell shrinkage produces spiny appearance 6-7 6-8 STRATUM GRANULOSUM STRATUM LUCIDUM Seen only in thick skin Consists of 3 to 5 layers flat keratinocytes Thin translucent zone superficial to stratum granulosum Contain coarse dark-staining keratohyalin granules Keratinocytes are densely packed with eleidin Produces lipid-filled vesicles Cells have no nucleus or that release a glycolipid by exocytosis of waterproof the other organelles skin Zone has a pale, featureless forms a barrier between surface cells and deeper layers of the epidermis appearance with indistinct cuts off surface strata from nutrient supply boundaries 6-9 6-10 STRATUM CORNEUM LIFE HISTORY OF KERATINOCYTES Keratinocytes are produced deep in the epidermis by stem cells in stratum basale some deepest keratinocytes in stratum spinosum also multiply and Up to 30 layers of dead, scaly, increase their numbers keratinized cells Mitosis requires an abundant supply of oxygen and nutrients deep cells acquire from blood vessels in nearby dermis Form durable surface layer once epidermal cells migrate more than two or three cells away from surface cells flake off the dermisdermis,, their mitosis ceases (exfoliate) Newly formed keratinocytes push the older ones toward the surface Resistant to abrasion, penetration, and water loss In 30 - 40 days a keratinocyte makes its way to the skin surface and flakes off slower in old age faster in skin injured or stressed calluses or corns – thick accumulations of dead keratinocytes on the hands or f 6-11 6-12 2 DERMIS Hypodermis Dermis – connective tissue layer Subcutaneous tissue beneath the epidermis More areolar and adipose than Ranges from 0.2 mm (eyelids) – 4 mm (palms & soles) dermis Composed mainly of collagen with Pads body elastic fibers, reticular fibers, and fibroblasts Binds skin to underlyyging tissues Well supplied with blood vessels, sweat glands, sebaceous glands, and nerve Drugs introduced by injection endings highly vascular & absorbs them quickly Dermal papillae - extensions of the dermis into the epidermis Subcutaneous fat forming the ridges of the fingerprints energy reservoir Layers papillary layer thermal insulation reticular layer is deeper part of dermis 6-13 8% thicker in women 6-146-14 SKIN COLOR OTHER FACTORS IN SKIN COLOR Melanin – most significant factor in skin color produced by melanocytes accumulate in the keratinocytes of stratum basale and stratum spinosum eumelanin – brownish black pheomelanin - a reddish yellow sulfur-containing pigment People of different skin colors have the same number of melanocytes dark skinned people produce greater quantities of melanin melanin granules in keratinocytes more spread out than tightly clumped melanin breaks down more slowly melanized cells seen throughout the epidermis Hemoglobin - red pigment of red blood cells light skinned people adds reddish to pinkish hue to skin melanin clumped near keratinocyte nucleus melanin breaks down more rapidly Carotene - yellow pigment acquired from egg little seen beyond stratum basale yolks and yellow/orange vegetables Amount of melanin also varies with exposure to concentrates in stratum corneum and subcutaneous fat ultraviolet (UV) rays of sunlight 6-15 6-16 ABNORMAL SKIN COLORS SKIN MARKINGS Cyanosis - blueness of the skin from deficiency of oxygen in the circulating Friction ridges – the markings on the fingertips that leave oily fingerprints on blood surfaces we touch airway obstruction (drowning or choking) everyone has a unique pattern formed during fetal development and remain unchanged throughout life lung diseases (emphysema or respiratory arrest) not even identical twins have identical fingerprints cold weather or cardiac arrest allow manipulation of small objects Erythema – abnormal redness of the skin due to dilated cutaneous vessels Pallor – pale or ashen color when there is so little blood flow through the skin Flexion lines (flexion creases) – lines on the flexor surfaces of the digits, that the white color of dermal collagggen shows through palms, wrists, elbows marks sites where the skin folds during flexion of the joints emotional stress, low blood pressure, circulatory shock, cold, anemia Albinism – genetic lack of melanin that results in white hair, pale skin, and Freckles and moles – tan to black aggregations of melanocytes pink eyes freckles are flat, melanized patches have inherited recessive, nonfunctional tyrosinase allele moles (nevus) are elevated melanized patches often with hair Jaundice - yellowing of skin and sclera due to excess of bilirubin in blood moles should be watched for changes in color, diameter, or contour may suggest malignancy (skin cancer) cancer, hepatitis, cirrhosis, other compromised liver function Hematoma – (bruise) mass of clotted blood showing through skin Hemangiomas (birthmarks) – patches of discolored skin caused by benign tumors of dermal blood capillaries Bronzing - golden-brown color of Addison disease (deficiency of glucocorticoid hormone) some disappear in childhood -- others last for life 6-17 capillary hemangiomas, cavernous hemangiomas,