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Integumentary system
 

Integumentary system

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    Integumentary system Integumentary system Presentation Transcript

    • Integumentary System Tissues in combination
    • Functions of Integument
      • Protection of underlying tissues
      • Excretion of salts, water, organic waste
      • Maintenance of normal body temp
      • Synthesis of vitamin D
      • Storage of nutrients
      • Sensitivity to touch, pressure, pain, temp
    • Skin is the largest organ of your body – 16% by weight
      • 2 Functional components
        • Cutaneous membrane – layers of tissues
        • Accessory structures – hair, nails, glands
      • Cutaneous membrane has 3 regions
        • Epidermis – epithelial layer
        • Dermis – CT layers
        • Hypodermis – fat layer (deep)
    • Epidermis
      • Stratified squamous epithelium in 4 (or 5) layers
        • 1. Stratum Germinativum (basale)
          • Deepest layer – basement membrane
          • Stem cells – replace shed cells
      • 2. Stratum spinosum
        • Bound together by desmosomes
        • Several cells thick
        • Spiky looking under microscope
      • 3. Stratum granulosum
        • Grainy layer
        • Make keratohyalin
      • 4. Stratum lucidum *
        • *only found on palms and soles
        • Clear layer
        • Makes eleidin
      • 5. Stratum corneum
        • True keratin develops from keratohyalin and eleidin
          • Keratin is tough, flexible, water resistant, fibrous protein
    • S. Corneum cont.
      • Cells become thin and flat
      • Become packed with keratin
      • Organelles break down and cells die
      • Eventually sloughed off
      • From mitosis; 6 weeks to new epidermis
      • Relatively dry – unattractive to microorganisms
      • Lipids are secreted by glands to maintain barrier
      • Xerosis – dry skin
    • Cornification
      • Accumulation of keratin – keratinized
      • Occurs everywhere except the surface of the eyes
      • Thin skin – 1.5 to 4mm; epidermis is .08mm, about 20 cell layers thick
      • Palms and soles have 30+ layers
    • Epidermal Ridges
      • Deeper layers of epidermis form ridges
      • Increased contact with dermis – diffusion of nutrients
      • Base for fingerprints (genetically determined)
        • Fingerprints provide grip
      • Monitored by nerves for touch, pressure, pain, temp. info.
    • UV Radiation
      • Vitamin D synthesis – sterol altered by UV
      • Stresses skin
        • Breaks down underlying CT
          • Wrinkles
        • Skin cancer
        • Destroys folate – folate helps protect against spina bifida
        • Tanning beds are as risky as the sun
    • Color of epidermis
      • 1. Underlying blood vessels – reddish
        • In dermis
      • 2. Carotene – orange yellow pigment
        • In epithelia
      • 3. Melanin – yellow brown to black
        • In between stem cells
    • Melanin
      • Secreted by melanocytes, passed to adjacent cells
        • Everyone has approximately the same number of melanocytes; but activity, and color and size of granules of melanin differs
      • Absorbs UV radiation, protects deeper layers
      • Activity increases with exposure to UV
        • Accelerates slowly – maxes about 10 days after initial exposure
    • Dermis
      • 1. Papillary (superficial) layer
      • 2. Reticular (deep) layer
      • Both contain fibers, blood vessels, lymphatic vessels, fat cells, muscle cells, nerve endings, and accessory structures
    • Papillary layer
      • Loose CT
      • Capillaries and nerves that supply epidermis
      • Named for dermal papillae (bumps) that project between epidermal ridges
    • Reticular layer
      • Dense irregular CT
      • Collagen fibers extend into papillary layer
      • Elastin fibers
    • Lines of Cleavage
      • Bundles of collagen tend to run parallel
      • Different areas of body are oriented differently
      • Surgeons use these lines to minimize scarring, heal faster
      • Stretch marks – bundles that have been pulled apart by rapid weight gain or pregnancy (perpendicular to lines of cleavage)
    • Hypodermis
      • Subcutaneous layer
      • Adipose tissue
      • Insulates against heat loss
      • Energy reserve
      • Cushioning for kidneys and babies
      • Collagen fibers extend into here from dermis
      • Hypodermic needle introduces drugs into fat layer, slowly enters circulation
    • Skin cancers
      • Basal cell carcinoma – S. germinativum cells are affected, most common type
      • Squamous cell carcinoma – also epithelial, more deadly than basal cell
      • Melanoma – cancer of melanocytes, most deadly form, more likely from severe burns
        • Size, shape, color
      • Moles – benign tumors of melanocytes
    • Accessory Structures
      • Hair
        • Found everywhere except: sides and soles of feet, palms of hands, sides of fingers and toes, lips, portions of external genitalia
        • Color – variations in melanin
          • Gray – pigment lessens
          • White – air bubble in shaft
    • Hair Follicle
      • Tube hair occupies
      • Deep into dermis
      • Structure
        • Papilla – bump containing nerves and blood vessels
        • Matrix – epithelium at base of follicle that forms hair, basal cells divide, cornification of outer layers
    • Hair Structure
      • Medulla – soft core closest to center of papilla; soft keratin
      • Cortex – farther out – hard keratin, stiffness
      • Cuticle – superficial – hard keratin coats hair
      • Root – enclosed by matrix, bulb of follicle
      • Shaft – the hair itself
        • Straight hair – round in cross section
        • Curly hair – flat or oval in cross section
    • Hair types
      • 1. Vellus hair – peach fuzz
      • 2. Terminal hair – heavy, dark, hair on head, eyebrows, eyelashes, etc.
      • 3. Intermediate hair – hair on arms and legs
      • Hormones change hair from one form to another
        • Puberty
        • Male pattern baldness
    • Hair loss may also be caused by
        • Drugs (chemo)
        • Dietary factors
        • Radiation
        • High fever
        • Stress
        • Pregnancy hormones
      • Hair grows 1/3mm per day
      • Stays in scalp for 2 – 5 years
      • 50 hairs lost per day is normal
    • Hair Functions
      • Control heat loss
        • Arrector pili – small smooth muscle that pulls on follicle to make hair stand up
          • Increases trapped air insulation
          • Causes goosebumps in humans
      • Reduces friction
    • Nails
      • Made of keratin at the nail root (not visible)
      • Lunula – pale crescent at base of nail
        • Blood vessels are obscured
      • Protection of finger and toe tips (claws in some animals)
    • Glands
      • Sebaceous glands
        • Holocrine glands found along hair follicles
        • Secrete sebum
          • Inhibits bacterial growth
          • Lubricates and protects hair shaft and skin
        • Contraction of arrector pili helps squeeze sebum onto skin surface
        • Sebaceous follicles discharge directly onto skin
    • Sweat glands
      • 1. Apocrine sweat glands – stinky sweat (bacteria that eat this sweat contribute to the smell)
        • Found in armpits, around nipples, groin
        • Associated with hair follicles
        • Send social chemical messages in mammals about sex
      • 2. Merocrine sweat glands – watery sweat (99% water, some salt, waste)
        • Cools the body “sensible perspiration”
        • Discharge onto skin surface
        • Palms and soles – 3000 per sq. in.
        • Flushes out microorganisms
        • Smaller than apocrine glands
    • Control of sweat glands
      • Sebaceous and apocrine are hormonally controlled; all on or all off
      • Merocrine are nerve controlled, can be regional
        • Sweaty palms
    • Ceruminous glands
      • Modified sweat glands in ear canal
      • Secretions mix with sebum to make cerumen – ear wax
        • Protection
        • Bug repellent
    • Nerve endings
      • Pain – free nerve endings in epidermis
      • Touch
        • Merkel’s discs – in epidermis
        • Meissner’s corpuscles – in papillae
        • Root hair plexus – around hair at base of follicle
      • Pressure – Pacinian corpuscle – in hypodermis
      • Cold – Krause corpuscle – in dermis, round
      • Heat – Ruffini corpuscle – in dermis, flattened
    •