INTEGUMENTARY SYSTEM

INTEGUMENTARY SYSTEM CHAPTER 6

INTEGUMENTARY SYSTEM • SKIN • Largest organ by weight • ACCESSORY STRUCTURES

SKIN • FUNCTIONS: • MAINTAIN HOMEOSTASIS • PROTECTIVE COVERING • PREVENT WATER LOSS • REGULATE BODY TEMPERATURE • SENSE RECEPTORS • SYNTHESIZES CHEMICALS • IMMUNE SYSTEM CELLS • EXCRETES SOME WASTE

CUTANEOUS MEMBRANE • EPIDERMIS • STRATIFIED SQUAMOUS EPITHELIUM • DERMIS • THICKER • CONNECTIVE TISSUE: DENSE IRREGULAR; AREOLAR; SMOOTH MUSCLE; NERVOUS TISSUE; BLOOD BASEMENT MEMBRANE: SEPARATES BOTH

SUBCUTANEOUS LAYERHYPODERMIS • AREOLAR AND ADIPOSE TISSUE • BINDS TO UNDERLYING ORGANS • FIBERS CONTIGUOUS WITH DERMIS • INSULATION: • CONSERVE HEAT? • MAJOR BLOOD VESSELS • RETE CUTANEUM

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EPIDERMIS • STRATIFIED SQUAMOUS • NO BLOOD VESSELS • LAYERS: • STRATUM BASALE (STRATUM GERMINATIVUM/ BASAL CELL LAYER) • STRATUM SPINOSUM • STRATUM GRANULOSUM • STRATUM LUCIDUM • STRATUM CORNEUM

STRATUM BASALE • LIVING: DIFFUSION • MITOSIS • NUCLEI • SINGLE ROW OF CUBOIDAL • MELANOCYTES

STRATUM SPINOSUM • MANY LAYERS • LARGE, CENTRAL, OVAL NUCLEI • KERATIN FIBERS FORMING • CELLS STARTING TO FLATTEN

STRATUM GRANUSLOSUM • 3-5 LAYERS • FLATTENED GRANULAR CELLS • KERATIN • SHRUNKEN NUCLEI

STRATUM LUCIDUM • IN THICKEST SPOTS: PALMS, SOLES • CLEAR CELLS: NUCLEI, ORGANELLES CAN’T BE SEEN

STRATUM CORNEUM • DEAD • KERATINIZED • DESMOSOMES • NONNUCLEATED • SQUAMOUS

EPIDERMAL HOMEOSTASIS • RUBBED OFF CELLS = MITOSIS • INCREASES IN AREAS OF HEAVIER WEAR • CALLUSSES, CORNS

EPIDERMAL FUNCTIONS • PROTECTION: • PREVENTS WATER LOSS • AGAINST MECHANICAL FORCE • AGAINST HARMFUL CHEMICALS • PREVENTS ENTRANCE OF PATHOGENS

MELANOCYTES • MELANOSOMES PRODUCE MELANIN FROM TYROSINE • SKIN COLOR • ABSORBS UV RADIATION • IN STRATUM BASALE BUT CELLULAR EXTENSIONS (PROCESSES) ALLOW MELANIN TO PASS TO KERATINOCYTES • KERATINOCYTES SEEM TO STIMULATE MELANOCYTES TO RELEASE MELANIN

SKIN COLOR • GENETICS & ENVIRONMENT • SAME NUMBER OF MELANOCYTES BUT DIFFER IN HOW MUCH MELANIN IS PRODUCED • DARK SKIN: MORE MELANIN; SINGLE, LARGE PIGMENT GRANULES • LIGHTER SKIN: SMALLER AND 2-4 GRANULES • ALBINISM: NO PIGMENT • SUNLIGHT, UV AND X-RAYS INCREASE PRODUCTION OF MELANIN: FADES • OXYGENATED BLOOD IN SKIN: LOTS OF BLOOD= PINK • CYANOSIS: LOW O2: DARK RED HEMOGLOBIN

DERMIS • DERMAL PAPILAE- ? • FINGERPRINTS • BINDS EPIDERMIS • DENSE IRREGULAR CONNECTIVE TISSUE • 1-2 MM (.5MM-3.0MM) • SMOOTH MUSCLE; SKELETAL MUSCLE • NERVE CELL PROCESSES: SENSORY AND MOTOR • SENSE RECEPTORS (CHAP 12)

ACCESSORY STRUCTURES • NAILS • NAIL PLATE, NAIL BED- SPECIALIZED EPITHELIAL CELLS • LUNULA- MITOSIS-TINY KERATINIZED SCALES

HAIR FOLLICLES • GROWTH CYCLE: 2-6 YEARS, REST, FALLS OUT, REPLACED • ON MOST SURFACES BUT NOT ALL AS DEFINED • HAIR FOLLICLE: EPIDERMAL CELLS AT BASE, HAIR ROOT: NOURISHED BY DERMAL BLOOD VESSELS • MOVE UP, KERATINIZE, DIE = HAIR SHAFT • BALDNESS: GENETIC DOMINANT/RECESSIVE

HAIR COLOR • GENES DETERMINE PIGMENT TYPE AND AMOUNT • MELANOCYTES: • EUMELANIN: DARK HAIR • PHEOMELANIN BLONDE, RED • TRICHOSIDERIN: RED • NO PIGMENT: WHITE • MIX OF WHITE AND PIGMENTED: GRAY: SOME INTERMEDIATE COLOR = GRAY

ARRECTOR PILI MUSCLE • ON EACH HAIR FOLICLE: GOOSE BUMPS • SMOOTH MUSCLE • INVOLUNTARY

SEBACEOUS GLANDS • SPECIALIZED GLANDULAR EPITHELIAL CELLS ASSOCIATED WITH HAIR FOLLICLES: PILOSEBACEOUS UNIT • BRANCHED ACINAR GLAND • HOLOCRINE: FATTY MATERIAL: SEBUM: BURSTS CELL: LIPID, WAX, CELL DEBRIES • INTO HAIR FOILLICLE; SOME TO SWEAT PORES (AREAS WITHOUT HAIR) • KEEPS HAIR AND SKIN SOFT, PLIABLE AND WATERPROOF • SCATTERED; NOT ON PALMS, SOLES; NOT ALL WITH FOLLICLES • SPECIALIZED: MEIBOMIAN GLANDS: SECRETION SLOWS EVAPORATION OF TEARS

SWEAT GLANDS • SUDORIFEROUS GLANDS • WIDESPREAD • BALL IN DERMIS OR SUBCUTANEOUS • SPECIALIZED GLANDULAR EPITHELIAL CELLS • MOST NUMEROUS/ FOUND IN MOST AREAS: ECCRINE: RESPOND TO INCREASED BODY TEMPS • ARE MEROCRINE: ODORLESS; MOSTLY H2O AND SALT, A LITTLE UREA • CONTROLLED BY SYMPATHETIC NERVOUS SYSTEM • APOCRINE GLANDS: ARE ACTUALLY MEROCRINE • MORE VISCOUS FLUID; DEVELOP SCENT FROM SKIN BACTERIA; ACTIVATED AT PUBERTY • IN ARMPITS, AREOLA, GENITALANAL AREA; HAIR FOLLICLES • STIMULATED BY ADRENALINE

MODIFIED SWEAT.T GLANDS: CERUMINOUS GLANDS AND MAMMARY GLANDS

REGULATION OF BODY TEMPERATURE • HOMEOSTASIS: HEAT PRODUCED= HEAT LOST • HEAT PRODUCTION: • CELLULAR RESPIRATION • SET POINT IN: • HYPOTHALAMUS: • VASODILATION/VASOCONSTRICTION • HEART

HEAT LOSS • RADIATION: • MAJOR PROCESS; • INFRARED • CONDUCTION: • TO COOLER OBJECT IN CONTACT (CHAIR/AIR) • CONVECTION: • WARMER AIR MOVES AWAY AND COOLER AIR IS THEN HEATED • EVAPORATION: • ECCRINE SWEAT GLANDS RELEASE SWEAT • EVAPORATES AND CARRIES HEAT AWAY

HEAT RETENTION • VASOCONSTRICTION: • STOPS RADIATION, CONDUCTION, CONVECTION, • SWEAT GLANDS INACTIVE • STOPS EVAPORATION • CONTRACTION OF MUSCLES WHICH COULD LEAD TO SHIVERING

HEAT REGULATION PROBLEMS • HOT, HUMID DAY: • NO EVAPORATION • HYPERTHERMIA • IF HOTTER THAN BODY TEMP MAY GAIN HEAT FROM ENVIRONMENT • PROLONGED COLD EXPOSURE/SICKNESS: • HYPOTHERMIA • SHIVERING • MENTAL CONFUSION, LETHARGY, LOSS OF REFLEXES, LOSS OF CONSCIOUSNESS, MAJOR ORGANS SHUT DOWN, DEATH • BODIES CORE CAN ONLY DROP A FEW DEGREES, EXTREMETIES CAN SURVIVE DROPS TO 20-30° F • RISK: HOMELESS, AGED, YOUNG, VERY THIN

HEALING • INFLAMMATION: • BLOOD VESSELS DILATE AND INCREASE PERMEABILITY: EDEMA • BECOME: RED, SWOLLEN, HOT, PAINFUL ? • BENEFIT: • PROVIDE MORE O2 AND NUTRIENTS

HEALING CUTS • SHALLOW: • EPITHELIAL CELLS INCREASE MITOSIS • DEEP: • BLOOD VESSEL CUT: CLOTTING • FIBRIN FORMED FROM ANOTHER BLOOD PROTEIN WHICH TRAPS PLATELETS • DRIES: SCAB • EPITHELIAL CELLS REPLICATE • FIBROBLASTS MOVE IN AND SECRETE COLLANGENOUS FIBERS • CONNECTIVE TISSUE MATRIX RELEASES GROWTH FACTORS INCREASE MITOSIS • BLOOD VESSELS EXTEND IN • PHAGOCYTES REMOVE DEAD CELLS AND DEBRIS • SCAB SLOUGHS OFF • SCAR COULD FORM

SCAR • TOO WIDE • GRANULATIONS FORM: • NEW BLOOD VESSEL AND FIBROBLASTS • SECRETE COLLAGENOUS FIBERS • BLOOD VESSELS ARE RESORBED, FIBROBLASTS MOVE • SCAR IS MOSTLY COLLAGENOUS FIBERS

BURNS • 1ST DEGREE: • PARTIAL THICKNESS: ONLY EPIDERMIS; REDNESS, MILD EDEMA,MAY SHED; • MILD SUNBURN • HEALS QUICKLY, NO SCARRING • 2ND DEGREE: • DEEP PARTIAL THICKNESS: EPIDERMIS AND SOME DERMIS;FLIUID LEAKS FROM CAPILLARIES: BLISTERS; DARK RED TO WAXY WHITE; • HOT OBJECTS OR LIQUIDS, FLAMES, BURNING CLOTHES; HEALING DEPENDS ON EPIDERMAL STEM CELLS IN ACCESSORY STRUCTURES OF DERMIS ?; • NO SCARRING UNLESS INFECTED

BURNS • 3RD DEGREE: FULL THICKNESS: • DESTROYS EPIDERMIS, DERMIS AND ACCESSORY STRUCTURES; LEATHERY, RED TO WHITE OR BLACK; • IMMERSION IN HOT LIQUIDS, PROLONGED EXPOSURE TO HOT OBJECTS, FLAMES OR CORROSIVE CHEMICALS; • SCARRING; GRAFTING MAY BE NEEDED: WHY? • AUTOGRAFT • ALLOGRAFT (MUST BE REPLACED) • SKIN SUBSTITUTES AMNIOTIC MEMBRANE, ARTIFICIAL MEMBRANES, CULTURED EPITHELIAL CELLS,

LIFE SPAN CHANGES • EPIDERMIS: • MITOSIS SLOWS: LARGER, IRREGULAR BUT LESS; SCALY: KERRATIN BONDS; ‘AGE SPOTS’ FROM OXIDATION OF GLANDS; • DERMIS: • FIBER PRODUCTION SLOWS: THINS; WITH LOSS OF ADIPOSE (SUBCUTANEOUS): WRINKLING; HEALING SLOWWS (LESS FIBROBLASTS); OIL PRODUCTION DECREASES: SKIN DRIES; • ACCESSORY GLANDS: • LESS MELANIN: WHITE HAIR; HAIR GROWTH SLOWS, HAIRS THIN, FOLLICLE NUMBER DECREASES, BALDNESS (MALES); LESS BLOOD TO NAILS: SLOWS GROWTH, HARDEN; LESS PAIN AND PRESSURE RECEPTORS;

LIFE SPAN CHANGES (CONT.) • TEMPERATURE CONTROL LESSENS: LESS SWEAT GLANDS AND LESS CAPILLARIES TO GLANDS; SHIVERING ABILITY LESSENS; LESS DEEPER BLOOD VESSELS AND LESS ABILITY TO SHUNT BLOOD TO INTERIOR: FEEL COLD; PALE: LESS BLOOD VESSELS IN SKIN; BED SORES: CHANGES IN BLOOD VESSELS; • GET LESS VITAMIN D AND GET OUTSIDE LESS: AFFECTS BONE MAY NEED SUPPLEMENTAL VITAMIN D;

THINGS TO KNOW • What is the integumentary system? The parts, membrane type, functions . • Layers, what is found there, functions • Layers of epidermis: what is present, purpose, melanocytes, • What determines skin color • Accessory structures: nails, hair, oil glands, sweat glands • How body temperature is regulated, heat is lost, retained, problems with regulation

How healing occurs in the different layers, scar formation • Characteristics of different types of burns, healing, grafting • Life span changes: epidermis, dermis, accessory glands, temperature control

INTEGUMENTARY SYSTEM