Integumentary system
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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
  •