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Skin and the Integumentary System

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Chapter 6. Skin and the Integumentary System. Functions of the Skin. Maintain homeostasis Protective covering Contains immune cells Synthesizes vitamin D Excretes wastes Slows water loss Regulates body temp Houses sensory receptors. Cut-, skin Derm -, skin Epi -, upon Hypo -, below.

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functions of the skin
Functions of the Skin
  • Maintain homeostasis
  • Protective covering
  • Contains immune cells
  • Synthesizes vitamin D
  • Excretes wastes
  • Slows water loss
  • Regulates body temp
  • Houses sensory receptors
layers of skin
Cut-, skin

Derm-, skin

Epi-, upon

Hypo-, below

Layers of Skin
  • 3 layers:
    • Epidermis
      • Outer layer
    • Dermis
      • Inner layer
    • Subcutaneous
      • Hypodermis layer
epidermis
Epidermis
  • Thickest on palms and soles
    • 0.8-1.4mm
  • Accessory structures
    • Hair follicles
    • Nails
  • Melanocytes
    • Provide melanin
epidermis1
Epidermis
  • Composed of stratified squamous epithelium
  • Keratinized
    • Cells synthesize keratin packed cells
  • Separated from dermis by basement membrane
  • Lacks blood supply
layers of epidermis
Layers of Epidermis
  • Stratum corneum
    • corneum= horn (Latin)
    • Outer keratinized layer, dead
    • Desquamation
  • Stratum lucidum
    • lucid= clear (Latin)
    • Palms, soles
  • Stratum granulosum
    • granulose= granular (Latin)
    • Flat, granular (keratohyalin)
layers of epidermis1
Layers of Epidermis
  • Stratum spinosum
    • Spiny, prickly
    • Dividing, melanocyte branches
  • Stratum basale (germinativum)
    • Basal = basement, bottom layer
    • Melanocytes, dividing, deepest layer
dermis
Dermis
  • Bind epidermis to underlying tissue
  • Irregular dense CT
  • Muscle fibers
    • Smooth & skeletal
  • Dermal papillae
    • Increased surface area to nourish epidermis
    • Fingerprints
    • Friction for gripping
  • Average thickness
    • 1.0-2.0mm
dermis1
Dermis
  • Accessory structures
    • Nerve cell processes
      • Pacinian (heavy touch/pressure)
      • Meissner’s (light touch/pressure)
      • Free nerve endings (temperature, pain)
    • Blood vessels
    • Sweat glands
subcutaneous layer
Subcutaneous Layer
  • “Hypodermis”
  • Loose CT & adipose tissue
  • Major blood vessels
  • Insulation
hair follicles
Hair Follicles
  • From epidermal cells
  • Extends into dermis
    • Contains hair root
  • Hair color
    • Melanin production
      • Albinism
  • Arrectorpili muscle
    • Smooth muscle
    • Attaches to each follicle
      • Autonomic innervation
hair growth
Hair Growth
  • Cyclic growth
    • Formed by cells in follicle
    • Keratinize and die
    • Form hair shaft
  • Type of hair
    • Eyelash
      • Grow 30 days, 100 days rest
    • Scalp
      • Grow 3-6 years, rest few months
      • 0.3 mm/day
sebaceous glands
Sebaceous Glands

Seb-, grease

  • Associate with hair follicles
    • Absent on palms and soles
  • Holocrineglands
    • Release entire cells
  • Secrete sebum
    • Mixture of fatty acids and cellular debris
    • Secreted into hair follicle
  • Excess sebum  acne
clinical application
Clogged gland

Excess sebum, epithelial cells

Blackheads & whiteheads

Good environment for anaerobic bacteria

Clinical Application
  • Acne
    • Disorder of sebaceous glands
  • Hormonally influenced
    • At puberty
    • Adrenals  androgens
    • Stimulates sebum production
clinical application1
Clinical Application
  • Immune system triggers inflammation
    • Pimple
  • Treatment options
    • Antibiotics
    • Estrogen
    • Retinoic acid (Vitamin A derivatives)
      • Accutane
nails
Nails
  • Protective coverings on fingers, toes
  • Made of:
    • Nail plate
    • Nail bed (skin)
    • Lunula
      • White region
      • Half-moon shape
      • Active in growth
  • Reflection of health status
    • Blue = cyanosis; white = anemia; pigment = injury or melanoma; depressions/furrows = anemia, malnourishment; red streaks = ulcers, hypertension, RA
  • Growth rate
    • 0.5-1.2 mm/day
sweat glands
Sweat Glands
  • Sudoriferous glands
    • Widespread in skin
      • Deep dermis or subcutaneous layer
  • Eccrine glands
    • Most numerous
  • Apocrine glands
    • Active in puberty
  • Modified sweat glands
    • Ceruminous
    • Mammary
sweat glands1
Sweat Glands
  • Eccrine glands
    • Most numerous
    • Response to
      • High temp
      • Exercise
      • Stress (on hands)
    • Open as pore
      • Forehead, neck, back
sweat glands2
Sweat Glands
  • Apocrine glands
    • Onset @ puberty
    • Response to
      • Fear
      • Pain
      • Distress
    • Open into hair follicle
      • Armpit
      • Groin
    • Odor
      • Bacterial metabolism of secretions

Sympathetic response

sweat
Sweat
  • Water
  • Salts
    • Sodium
    • Chloride
    • Potassium
    • Magnesium
  • Wastes
    • Urea
    • Lactate
regulation of body temp
Regulation of Body Temp
  • Heat
    • Product of cellular metabolism
  • Active cells are major heat producers
    • Skeletal muscle
  • As body temp , body releases heat
  • Homeostasis
    • Maintain body temp at 37C or 98.6F
releasing body heat
Releasing Body Heat
  • Radiation (2)*
    • Most of heat loss
    • Infrared heat rays escape from warmer to cooler surroundings
  • Evaporation (5)*
    • At high temp, eccrine sweat glands release sweat onto skin
    • Heat carried away as skin cools
  • Conduction
    • Heat transferred from body directly to cooler object
    • Ex. Cold car seats
  • Convection (4)
    • Warm air circulates away from body
conserving body heat
Conserving Body Heat
  • Dermal blood vessels
    • Reduce heat-carrying blood thru skin
  • Muscle activity
    • Increased cell respiration
      • Heat production
    • Shivering
      • Small groups of muscles contract
      • Produce heat
problems in body temp regulation
Problems in Body Temp Regulation
  • Hyperthermia
    • Abnormally high
    • Humid air prevents evaporation of sweat
      • No cooling
    • High air temp reduces radiation cooling
  • Hypothermia
    • Abnormally low
    • Shivering  mental confusion, lethargy, loss of reflexes, shut down of major organs
      • Some surgeries (heart, brain) require body to be cooled  less oxygen is required
skin color
Skin Color
  • Genetic Factors
    • Melanocytes
      • Same # in all people
    • Melanin production
      • Varies by person
    • Melanin production
      • High  darker skin
      • Low  fairer skin
    • Albinism
      • No melanin
  • Environmental factors
    • Darken existing melanin
    • Stimulate production
      • Sunlight
      • UV light from
        • Sunlamps
      • X rays
    • Tans fade
      • Pigmented epidermal cells keratinize
      • Wear away
skin color1
Skin Color
  • Physiological Factors
    • Blood vessels in dermis adds color
      • Content of vessels
        • High oxygen  hemoglobin is bright red
          • Pinkish hue to skin
        • Low oxygen  hemoglobin is dark red
          • Bluish hue to skin (cyanosis)
      • State of vessels
        • Dilation  skin reddens
        • Constriction  skin pales
  • Dietary influences
    • Carotene  yellow/orange skin tone
  • Health influences
    • Jaundice  yellowish skin (liver)
healing of wounds and burns
Healing of Wounds and Burns
  • Inflammation
    • Response to injury or stress
    • Healing events depend on nature of injury
  • Cuts
    • Shallow
      • Epithelial cells divide  fill in gap
    • Deep cut
      • Blood vessels break  blood clot
healing of wounds and burns1
Healing of Wounds and Burns
  • Clot
    • Scab formation
      • Fibrin, blood cells, platelets, fluids
  • Fibroblasts
    • Secrete collagen
      • Binds wound together
  • Scar
    • Extensive wound
    • Connective tissue on skin surface
burns
Burns
  • First degree
    • Superficial partial thickness
      • Injuring epidermis only
      • Healing in 2-3 days
    • Common examples
      • Sunburn
      • Scalding water
      • Chemicals
    • Treatment
      • Flush with cool water (no ice)
      • Aloe (no oil)
      • Clean, dry bandage
burns1
Burns
  • Second degree
    • Deep partial thickness
      • Injures epidermis and dermis
      • Fluid escapes capillaries  blisters
      • Healing time 1-2 weeks
    • Common examples
      • Prolonged sunburn or scalding water
      • Brief exposure to flame
    • Treatment
      • Flush with water, bandage
      • Do NOT break blisters
      • > 2-3 inches, see physician
        • Hydration
        • Antibiotics
        • Grafting
burns2
Burns
  • Third degree
    • Full-thickness
      • Epidermis, dermis, accessory organs
      • Healing time: weeks to months
    • Common examples
      • Contact with flame
      • Corrosive chemicals
      • Immersion in hot liquids
    • Treatment
      • Burn center
      • Debridement
      • Grafting
grafting
Grafting
  • Autograft
    • “Auto”  self
      • Remove skin from unburned part of body and “transplant” it to injured site
  • Homograft
    • “Homo”  like
      • Cadaveric skin used if can’t do autograft
  • Skin substitutes
    • Amniotic membrane
    • Artificial membrane
    • Cultured epithelial cells
  • Scarring
healing of burns
Healing of Burns
  • Treatment of patient:
    • Requires estimate of body surface injury
      • Replace body fluids and electrolytes
      • Determine amount of skin needed for graft
    • Use “rule of nines”
      • Divide skin surface into regions
      • Each region = 9% (or multiple of 9%)
life span changes aging skin shows many signs
Life Span ChangesAging skin shows many signs…
  • Cell cycle slows
  • Age (liver) spots
  • Dermis reduced
    • Connective tissue growth slows
      • Slower wound healing
    • Loss of fat
      • Wrinkles & sagging skin
  • Melanin production slows
    • Hair grays/whites
  • Less vitamin D production
    • Needed for calcium uptake in bones
life span changes aging skin shows many signs1
Life Span ChangesAging skin shows many signs…
  • Hair growth slow
    • Thins and # follicles decreases
  • Lowered blood supply to nail beds
    • Dulls/hardens nails
  • Sensory receptors decline
    • Less sensitive to pain/pressure
  • Inability to control body temperature
    • # sweat glands drop & dermis blood vessel numbers
common skin disorders
Common Skin Disorders
  • Athlete’s foot
    • Skin fungus infection (Tineapedis)
  • Boil
    • Bacterial infection, bacteria enter skin via follicle
  • Chickenpox
    • Varicella-zoster infection; blistery lesions that scab
common skin disorders1
Common Skin Disorders
  • Eczema
    • Dry, itchy, scaly skin (genetic)
  • Mole
    • Benign skin tumor (nevus) usually pigmented brown black
  • Psoriasis
    • Red skin w/ silvery scale
rashes
Rashes
  • Infectious
    • Roseola
    • Measles
    • Rubella
    • 5th disease
    • Shingles
    • Impetigo
    • Lyme disease
    • RMSF
    • Meningitis
    • Candidiasis
  • Allergic
    • Hives
    • Penicillin
    • Food allergies
    • Poison ivy
    • Cosmetics
  • Autoimmune
    • Lupus
    • Psoriasis
skin cancer types
Skin CancerTypes
  • Basal cell carcinoma
    • Most common
    • Basal layer of epidermis
    • Nodule, shiny bump, scar-like lesion
  • Squamous cell carcinoma
    • 2nd most common
    • Upper layers of skin (squamous)
    • Begin as scaly red patches, open sores, elevated with centralized depression
    • Typically superficial
skin cancer types1
Skin CancerTypes
  • Malignant melanoma
    • Most deadly
    • Brown/black patches, nodules
    • Look like or arise from moles
skin cancer risks
Skin CancerRisks
  • Fair skin, hair, eye color
  • Family history
  • Personal history
  • Chronic sun exposure
  • History of sunburns early in life
  • Certain types of moles, # moles
  • Freckles
    • Sun sensitivity, sun damage
skin cancer detection
Skin CancerDetection
  • A
    • Asymmetry
  • B
    • Border irregularity (scalloped, notched)
  • C
    • Color variation
  • D
    • Diameter > ¼ inch
  • E
    • Evolution
skin cancer treatment
Skin CancerTreatment
  • Excision
    • Virtually all types of skin cancer are 100% curable if caught early
  • Invasive
    • Lymph node testing
    • Chemotherapy
    • Immunotherapy
suggested homework problems
Suggested Homework Problems
  • Chapter assessments
    • 3-6, 9, 11-14, 17, 19-25, 27, 28
  • Integrative Assessments/Critical Thinking
    • 1-7
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