Integumentary System Chapter 5 Notes PDF

Integumentary system The epidermis ◦ composed of epithelial cells ◦ Outermost protective shield of the body ◦ Non vascularized Epidermis ◦ Nutrients reach epidermis by diffusion The underlying dermis ◦ composed mostly of connective tissue ◦ Tough...

Integumentary system The epidermis ◦ composed of epithelial cells ◦ Outermost protective shield of the body ◦ Non vascularized Epidermis ◦ Nutrients reach epidermis by diffusion The underlying dermis ◦ composed mostly of connective tissue ◦ Tough Dermis ◦ Making up the bulk of the skin ◦ Vascularized The subcutaneous tissue ◦ lies deep to the skin Subcaneous ◦ not part of the skin but shares hypodermis protective functions ◦ Composed of adipose tissue and areolar connective tissue ◦ Anchors the skin to underlying structures ◦ Also known as ‣ hypodermis ‣ Super cial fascia Cells of the epidermis Keratinocytes ◦ produce keratin ◦ Most cells are keratinocytes ◦ Tied together by desmosomes for strength ◦ Arise at stratum basale ◦ Continuous mitosis ◦ New epidermis every 25 to 45 days Melanocytes ◦ spider shaped cells ◦ Made in melanosomes ◦ Deepest layer of epidermis ◦ Synthesize the pigment melanin ‣ Keratinocytes accumulates melanin on their super cial portion forming a UV-blocking pigment layer  Dendritic cells ◦ star shaped ◦ Arise from bone marrow and migrate to epidermis ◦ Ingest foreign substances ‣ immune system Tactile epithelial cells ‣ Phagocytes ◦ may be present in the epidermal-dermis junction ◦ Spiky hemisphere shaped ◦ Functions as sensory receptor for touch Layers of epidermis Stratum Corneum ◦ 20 to 30 layers (3/4 of epidermis layer) ◦ Sheds regularly ◦ Keratin Stratum Lucidum ◦ only found in thick skin ‣ palms, soles, ngertips Stratum ◦ Consists of dead keratinocytes Corneum Stratum Granulosum ◦ consist of 1 to 5 layers ◦ Keratinization begins ◦ Keratin and glycolipids are found in extracellular space Stratum Spinosum ◦ Resist cell tension Stratum ◦ Anchored to the desmosomes granulosum ◦ Pre keratin Stratum Basale Stratum ◦ deepest layer ◦ Continually renewing cells Spinosum ‣ youngest keratinocytes ◦ Mitosis occurs here Stratum ‣ one daughter cell is pushed into basale the cells layer to begin forming mature keratinocytes and the other daughter cell remains in basal layer to produce new keratinocytes ◦ 10-25% of cells are melanocytes Layers of the dermis Papillary layer Derm ◦ composed of areolar connective tissue Papill ‣ collagen and elastic bers Papa Allows phagocytes patrol are for bacteria ◦ Dermal papillae contains Dermisre ‣ Capillary loops ‣ Free nerve endings ‣ Tactile corpuscles Reticular layer ◦ 80% of thickness of dermis ◦ Dense irregular connective tissue ‣ Extracellular matrix of reticular dermis epidermis contains collagen and elastic ◦ Cleavage (tension) lines ‣ Separation between the bundles of collagen bers ‣ Incisions made parallel to cleavage lines (heals rapidly) p pipit ◦ Flexture lines ‣ folds near joints, wrist, ngers, soles Refastar and toes ‣ Dermis tightly secured to deeper structures ◦ Stretch marks Cleavage ie ‣ tear of dermis During pregnancy or fast muscle lines growth Flexurelines 885 Melanin Made of tyrosine It’s two forms range in color from reddish yellow to brownish black Melanin synthesis depends on tyrosinase Difference is skin color re ect the kind and amount of melanin made and retained Carotene Yellow to orange pigment ◦ fount in certain plant products such as carrots accumulates in ◦ stratum corneum ◦ Fat of subcutaneous tissue Blueness (cyanosis) Can be converted to vitamin A Poor oxigynation results in bluish-gray ◦ normal vision and epidermal health tint Hemoglobin ◦ nails beds and mucous membranes Pinkish hue of or fair skin that circulates Sign of cardiovascular and respiratory through dermal capillaries issues Epidermis is almost transparent allowing Pallor or blanching color to show Emotional stress Bruses Blood moves from skin to organs ◦ person looks white Redness or erythema May indicate blushing, fever, in ammation, or allergy Yellowness If liver doesn’t function properly to eliminate bilirubin, yellow pigments Cyanosis starts to accumulate in body tissue ◦ example: white part of eyes Yellowness Red/purple/green/yellow marks Pallor Bruises/ecchymoses/ hematomas ◦ occurs when blood vessels are damaged and leak Black or brown necklace of bruises ◦ dark areas in the axillae and neck ‣ sometimes mistaken for being Brown dirty ◦ may be a sign of insulin resistance and elevated blood glucose Structure of hair AT Hair or pili ◦ exible strands produced by hair follicles FFEIIfii.IE ◦ consist mainly of dead keratinized Harroo cells Cuticle 3 concentric layers of keratinized cells ama ◦ Medulla Cortex ‣ central core Medull ‣ consist of large cells and air Haatrix spaces ‣ contains soft keratin HairPapi Melanocyte ‣ absent in ne hairs ◦ Cortex ‣ bulky layer around medulla ‣ consist of several layers of at cells ‣ Melanin uptake via cortical cells (keratinocytes) Hair pigment ◦ Cuticle Made by melanocytes ‣ formed when single layer of ◦ Made at the base of the hair follicle and cells overlap one another transferred to cortical cells ‣ helps separate neighboring Different concentrations of melanin produce hair color hair ◦ Red comes from pheomelanin doesn't mat When melanin production decreases ‣ most keratinized ◦ Air bubbles replace melanin and hairs turn gray or ‣ Provide strength and keeps white them tightly compact Hairshaft Arrector pili muscle ◦ found outside the wall of the hair follicle ◦ Causes goose bumps Vellus hair ◦ children and adult women ◦ pale and ne hair Arreaty ‣ arm, ngers I Terminal hair Sebgg ◦ coarser, longer and darker hair ‣ lashes, brows, scalp Hairroot Hairbulb  Folliculewall Hair follicle Fold down from epidermal surface into Periphedelsee subcutaneous tissue Glasshembrane It expands and forms a hair bulb ERSExt ◦ a sensory nerve ending wraps around bulb rootsheath Hair papilla Int rootsheath Dermal papillae ◦ Protrudes into hair bulb ◦ Supplies nutrients to growing hair and signals to grow Wall of hair follicle and its components Peripheral connective tissue sheath ( brous sheath) Nails contain hard keratin (like hair) ◦ derived from dermis Epidermis has soft keratin ◦ Forms external layer of wall Nail plate rest on nail bed Glassy membrane ◦ deep to nail plate ◦ junction of the brous sheath and epithelial ◦ contains deep layers of epidermis roots sheath nail matrix ◦ Basement membrane of follicle epithelium ◦ responsible for nail growth ◦ Derived from epidermis ◦ Nails cells produced by matrix Epithelial root sheath become heavily keratinized and the ◦ derived from epidermis nail body slides over nail bed ◦ Two components Lunule ‣ external ◦ white crescent continuation from epidermis Hyponychium ‣ internal ◦ Dirt accumulates derived from matrix cell Cuticle also called eponychium Eee lunule Poit plate ease noblate cuticle pagged matrix hatefold Cuticle bone Hyponychium 191 Sweat glands (sudoriferous glands) All over body ◦ except nipples and parts of external genitalia Moonamommodamseat sees up to 3 million per person Two types ◦ eccrine and apocrine Myoepithelial ◦ cells that contract when stimulated by nervous system Eccrine glands aa.si oWmMaoM They are merocrine ◦ meaning they are secreted by exocytosis as they are produced More than apocrine glands More Found everywhere but mainly ◦ palms, soles, and forehead simple coiled tubular gland Secretory part is coiled in dermis and duct extends to the skin surface as a pore ◦ sweat is secreted ‣ helps cooling Some antibacterial properties sweat features ◦ released by exocytosis ◦ 99% water, salts, metabolic waste, dermcidin ◦ PH between 4 and 6 ◦ Role is to prevent the body overheating Apocrine sweat glands They are merocrine ◦ meaning they are secreted by exocytosis as they are produced ‣ secretes true sweat, fatty substance and proteins odorless until bacteria decomposes organic molecules About 2000 glands Begins functioning at puberty (may act as sexual scent glands) ◦ androgens Found in ◦ axillary, anogenital area Larger than eccrine, lie deeper in dermis, ducts empty in hair follicles May be human equivalent of other animals sexual glands ◦ sexual foreplay increases activity ◦ They enlarge and recede with the phases of women cycle ◦ Their secretions may act as pheromones  Modi ed apocrine glands Ceruminous glands ◦ found in lining of the external ear canal ◦ Secretion mixes with sebum produced by sebaceous glands ‣ secretion is earwax or cerumen Mammary glands ◦ secretes milk ◦ Found in breast tissue Sebaceous gland they are holocrine ◦ Meaning they release product until rupture ◦ Simple branched alveolar glands Increase activity during puberty ◦ under the in uence of male sex hormones ‣ androgens Found all over body ◦ except soles, thigh skin of hands small on body trunk and limbs ◦ but large in face neck and upper chest Secrete sebum ◦ into hair follicle ◦ Occasionally pore on the skin surface ‣ softens and lubricates skin ‣ Sebum help prevent water loss and antibacterial properties Skin protection Chemical barriers ◦ skin secretions and melanin ‣ acid mantle pH is so low that slows down bacteria multiplication ‣ also secretes defensins punch holes in bacteria making them leaky Physical barrier ◦ Hardness of keratinized cells provide barrier Biological barriers ◦ Dendritic cells ‣ in epidermis ‣ Patrol on skin surface - engul ng any invaders then leaving the skin to the nearest lymph node ◦ Dermal macrophages ‣ second line of defense Cutaneous sensation Tactile (meissners) corpuscles ◦ in dermal papillae ◦ Makes us aware of the feeling of our clothes Lamellar (pacinian) ◦ Deeper dermis or subcutaneous tissue ◦ Alerts us to vibration or deep pressure Body tempt regulation As long as the external temperature is lower than body temperature, the skin will lose heat to the air Metabolic functions Sunlight stimulates modi ed cholesterol molecules Skin cancer Basal cell carcinoma ◦ least malignant and most common ◦ Stratum básale cells grow rapidly, invading dermis and subcutaneous tissue ◦ Develops from the youngest keratinocytes ◦ Occur most often on sun exposure areas of the face ‣ appear shiny dome shaped ‣ Layer develops to a ulcer with pearly edge Squamous cell carcinoma ◦ Second most common ◦ From the keratinocytes of the stratum spinosum ◦ Looks like a scaly reddened papule ‣ appears at the scalp, ears, lower lip and hands ◦ grow rapidly if not removed Melanoma ◦ most dangerous ◦ Melanoma can begin wherever there’s pigment ◦ Appear spontaneously ◦ Black to brown patch ◦ One third develop from moles ◦ Tried to get to surroundings of lymph and blood vessels Burns Tissue in icted by intense 1st ◦ heat, chemicals, electricity, radiation etc Loss of body uids First degree burn Only epidermis is Second degree burn damaged Damages epidermis and upper dermis 2nd Redness, swelling and pain Blisters also appear Heals in 2 to 3 days Heals in 3 to 4 weeks without attention Third degree burn Full thickness burns No pain since nerve ending have been destroyed Skin grafting is advised 3rd Considered critical if ◦ over 25% of the body has 2nd degree ◦ Over 10% of the body has 3rd degree determine by rule of 9s ◦ Divides body into 11 areas ‣ each counts for 9% of total body areas ‣ Genitals counts for 1%