Week 6 Lecture 1 Chapter 5 The Integumentary System

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Week 6 Lecture 1 Chapter 5The Integumentary
System

• Skin and its accessory structures
• structure
• function
• growth and repair
• development
• aging
• disorders

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General Anatomy

• A large organ composed of all 4 tissue types
• 22 square feet
• 1-2 mm thick
• Weight 10 lbs.

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• The skin protects us against environmental
  hazards. Its the FIRST LINE OF DEFENSE
• The skin helps regulate body temperature.
• The skin is always being attacked by
  micro-organisms
• Skin makes up about 16 of the total body weight.
  
• Tanning ancient Rome women lightened their skin
  with lead based cosmetics. At the time of
  Shakespeare before industrial revolution
  un-tanned skin high status
• Europe 18/19th century fair skin with freckles
  was attractive while tan skin manual labor like
  a farmer
• 20th century- indoor work increased. Tan skin
  leisure class. 1920 Coco Channel accidentally got
  tan on French Riviera. She ignited a fad.

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Introduction to the Integumentary System

• Connections
• Cardiovascular system
• Blood vessels in the dermis
• Nervous system
• Sensory receptors for pain, touch, and
  temperature

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Skin Functions

• Protection of underlying tissues and organs
  against impact, abrasion, fluid loss and chemical
  attacks.
• Excretion of salts, water, wastes. 500 ml a day1
  pint
• Temperature- via adipocytes which insulate to
  keep warmer, or evaporative ( sweating ) for
  cooling.
• Synthesis of D3 ( cholcalciferol )Sunlight hits
  the skin, and the subcutaneous cholesterol
  stimulates D3 which will go to the liver where it
  will make some intermediary products which will
  go to the kidney which in turn will make
  Calcitriol. This will increase the absorption of
  calcium and phosphorous from the GI tract and
  increase the deposition to he bones.
• Stores lipids in adipocytes
• Detects touch, pressure, pain, temperature, and
  relays to the neural system.

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Overview

• 2 Major layers of skin
• epidermis is epithelial tissue only
• dermis is layer of connective tissue, nerve
  muscle
• Subcutaneous tissue (subQ or hypodermis) is layer
  of adipose areolar tissue
• subQ subcutaneous injection
• intradermal within the skin layer

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Overview of Epidermis

• Stratified squamous epithelium
• Mechanical protection
• Keeps micro-organisms outside
• Contains no blood vessels
• 4 types of cells
• 5 distinct strata (layers) of cells

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Cell types of the Epidermis

• Keratinocytes--90
• produce keratin
• Melanocytes-----8
• produces melanin pigment
• melanin transferred to other cells with long cell
  processes
• Langerhan cells
• from bone marrow
• provide immunity
• Merkel cells
• in deepest layer
• form touch receptor with sensory neuron

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Epidermis

• Thin Skin
• Covers most of the body
• Has four layers of keratinocytes
• Thick Skin
• Covers the palms of the hands and soles of the
  feet
• Has five layers of keratinocytes

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Layers (Strata) of the Epidermis

• Strata means LAYER
• Stratum corneum
• Stratum lucidum
• Stratum granulosum
• Stratum spinosum
• Stratum basale

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Epidermis

• Stratum Germinativum-basale ( basal cell
  carcinoma )
• The germinative layer
• Has many germinative (stem) cells or basal cells
• Is attached to basal lamina by hemidesmosomes
• Forms a strong bond between epidermis and dermis
• Forms epidermal ridges (e.g., fingerprints)
• Dermal papillae (tiny mounds)
• Increase the area of basal lamina
• Strengthen attachment between epidermis and
  dermis

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Epidermis

• Figure 54 The Epidermal Ridges of Thick Skin.

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Epidermis

• Specialized Cells of Stratum Germinativum
• Merkel cells
• Found in hairless skin
• Respond to touch (trigger nervous system)
• Melanocytes
• Contain the pigment melanin or not with
  albinism
• Scattered throughout stratum germinativum

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Epidermis

• Stratum Spinosum
• The spiny layer
• Produced by division of stratum germinativum
• Eight to ten layers of keratinocytes bound by
  desmosomes
• Cells shrink until cytoskeletons stick out
  (spiny)
• Continue to divide, increasing thickness of
  epithelium
• Contain dendritic (Langerhans) cells, active in
  immune response

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Stratum Granulosum

• 3 - 5 layers keratinocytes
• Show nuclear degeneration
• Contain dark-staining keratohyalin granules
• Contain lamellar granules that release lipid that
  repels water
• Highest level where living cells are found.

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Epidermis

• Cells of Stratum Granulosum
• Produce protein fibers
• Dehydrate and die
• Create tightly interlocked layer of keratin
  surrounded by keratohyalin

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Stratum Lucidum

• Seen in thick skin on palms soles of feet
• Three to five layers of clear, flat, dead cells
• Contains keratin

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Stratum Corneum

• Exposed layer
• 25 to 30 layers of flat dead cells filled with
  keratin and surrounded by lipids
• Continuously shed takes about 15-30 days for
  cells to go from the basal layer to corneum
• Barrier to light, heat, water, chemicals
  bacteria
• Coats surface with lipid secretions form
  sebaceous glands
• Friction stimulates callus formation

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• The skin is water resistant not water proof. So
  we lose about 500 ml or 1 pint of water a day.
  This is called insensible perspiration.
• Ocean water is hypertonic. Water leaves the body
  which results in dehydration. In pool water
  (hypotonic) the water crosses the epithelium and
  can increase the size of cells 4 x the size. This
  is seen in the soles and palms.

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Keratinization Epidermal Growth

• Stem cells divide to produce keratinocytes
• As keratinocytes are pushed up towards the
  surface, they fill with keratin
• 4 week journey unless outer layers removed in
  abrasion. Dead cells can remain an additional 2
  weeks before shedding.
• Hormone EGF (epidermal growth factor) can speed
  up process
• Psoriasis chronic skin disorder
• cells shed in 7 to 10 days as flaky silvery
  scales
• abnormal keratin produced

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Skin Grafts

• New skin can not regenerate if stratum basale and
  its stem cells are destroyed
• Skin graft is covering of wound with piece of
  healthy skin
• autograft from self
• isograft from twin
• autologous skin
• transplantation of patients skin grown in culture

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Dermis

• Connective tissue layer composed of collagen
  elastic fibers, fibroblasts, macrophages fat
  cells
• Contains hair follicles, glands, nerves blood
  vessels
• Major regions of dermis
• papillary region -superficial
• reticular region deeper
• Tattoo ink is held here
• Phagocytes digest the ink

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Papillary Region

• Top 20 of dermis- Superficial layer
• Composed of loose CT elastic fibers
• Finger like projections called dermal papillae
• Functions
• anchors epidermis to dermis
• contains capillaries that feed epidermis
• contains Meissners corpuscles (touch) free
  nerve endings (pain and temperature)
• Its where dermatitis takes place.

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Reticular Region

• Dense irregular connective tissue
• Contains interlacing collagen and elastic fibers
• Packed with oil glands, sweat gland ducts, fat
  hair follicles
• Provides strength, extensibility elasticity to
  skin
• stretch marks are dermal tears from extreme
  stretching

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Skin Color Pigments (1)

• Melanin produced in epidermis by melanocytes
• same number of melanocytes in everyone, but
  differing amounts of pigment produced
• results vary from yellow to tan to black color
• melanocytes convert tyrosine to melanin
• UV in sunlight increases melanin production
• Clinical observations
• freckles or liver spots melanocytes in a patch
• albinism inherited lack of tyrosinase no
  pigment
• vitiligo autoimmune loss of melanocytes in
  areas of the skin produces white patches

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Skin Color Pigments (2)

• Carotene in dermis
• yellow-orange pigment (precursor of vitamin A)
• Found in carrots and squash
• Found in stratum corneum dermis
• Hemoglobin
• red, oxygen-carrying pigment in blood cells
• if other pigments are not present, epidermis is
  translucent so pinkness will be evident
• When scared someone looks white as a ghost b/c
  blood went from skin gt muscles
• Skin gets flushed and red when body temp
  increases b/c superficial blood vessels dilate so
  skin acts as a radiator to lose heat.
• Scarlet fever Strep attacks RBC- the hemoglobin
  leaks into the interstitial cells.

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Skin Color as Diagnostic Clue

• Jaundice
• yellowish color to skin and whites of eyes
• buildup of yellow bilirubin in blood from liver
  disease
• Cyanotic
• bluish color to nail beds and skin
• hemoglobin depleted of oxygen looks purple-blue
• Erythema
• redness of skin due to enlargement of capillaries
  in dermis
• during inflammation, infection, allergy or burns

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Skin Color

• Figure 55b Melanocytes.

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Skin Color

• Function of Melanocytes
• Melanin protects skin from sun damage
• Ultraviolet (UV) radiation
• Causes DNA mutations and burns that lead to
  cancer and wrinkles
• Skin color depends on melanin production, not
  number of melanocytes

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Skin Color

• Capillaries and Skin Color
• Oxygenated red blood contributes to skin color
• Blood vessels dilate from heat, skin reddens
• Blood flow decreases, skin pales
• Cyanosis
• Bluish skin tint
• Caused by severe reduction in blood flow or
  oxygenation

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Skin Color

• Illness and Skin Color
• Jaundice
• Buildup of bile produced by liver
• Yellow color
• Addison disease
• A disease of the pituitary gland
• Skin darkening
• Vitiligo
• Loss of melanocytes
• Loss of color

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Vitamin D3

• Vitamin D3
• Epidermal cells produce cholecalciferol (vitamin
  D3)
• In the presence of UV radiation
• Liver and kidneys convert vitamin D3 into
  calcitriol
• To aid absorption of calcium and phosphorus
• Insufficient vitamin D3
• Can cause rickets

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Vitamin D3

• Figure 57 Rickets.

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Skin Color

• Figure 56 Skin Cancers.

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Hair

• The human body is covered with hair, except
• Palms
• Soles
• Lips
• Portions of external genitalia
• Functions of Hair
• Protects and insulates
• Guards openings against particles and insects
• Is sensitive to very light touch

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Accessory Structures of Skin

• Epidermal derivatives
• Cells sink inward during development to form
• hair
• oil glands
• sweat glands
• nails

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Structure of Hair

• Shaft -- visible
• Root -- below the surface
• Follicle surrounds root
• base of follicle is bulb
• blood vessels
• germinal cell layer

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Hair Related Structures

• Arrector pili
• smooth muscle in dermis contracts with cold or
  fear.
• forms goosebumps as hair is pulled vertically
• Hair root plexus
• detect hair movement

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Hair

• Figure 510 Hair Follicles and Hairs.

A Single Hair Follicle
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Functions of Hair

• Prevents heat loss
• Decreases sunburn
• Eyelashes help protect eyes
• Touch receptors (hair root plexus) senses light
  touch
• Healthy loss is 50 a day.

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Glands of the Skin

• Specialized exocrine glands found in dermis
• Sebaceous (oil) glands
• Sudiferous (sweat) glands
• Ceruminous (wax) glands
• Mammary (milk) glands

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Sebaceous (oil) glands- Holocrine gland

• Secretory portion in the dermis
• Most open onto hair shafts
• Sebum
• combination of cholesterol, proteins, fats
  salts
• keeps hair and skin soft pliable
• inhibits growth of bacteria fungi(ringworm).
  The sebaceous glands forces lipids into the hair
  follicle and onto the skin creating a seal.
• Acne- ( can be a sign of EPA deficiency )
• Bacterial inflammation of glands
• secretions stimulated by hormones at puberty

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Sudoriferous (sweat) glands

• Merocrine (sweat) glands
• most areas of skin
• secretory portion in dermis with duct to surface
• regulate body temperature with perspiration
• Apocrine old name. its now called Merocrine
  (sweat) glands
• armpit and pubic region
• secretory portion in dermis with duct that opens
  onto hair follicle
• secretions more viscous the sweat produced is a
  nutrient for bacteria which intensifies the odor.

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Ceruminous glands

• Modified sweat glands produce waxy secretion in
  ear canal
• Cerumin contains secretions of oil and wax glands
• Helps form barrier for entrance of foreign bodies
• Impacted cerumen may reduce hearing
• Mammary Glands produce milk found in both
  sexes, but rudimentary until puberty. With
  estrogen they develop, with testosterone they are
  inhibited.

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Nails

• Nails protect fingers and toes
• Made of dead cells packed with keratin
• Metabolic disorders can change nail structure
• Nail production
• Occurs in a deep epidermal fold near the bone
  called the nail root

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Structure of Nails

• Tightly packed keratinized cells
• Nail body
• visible portion pink due to underlying
  capillaries
• free edge appears white
• Nail root
• buried under skin layers
• lunula is white due to thickened stratum basale
• Eponychium (cuticle)
• stratum corneum layer
• Nail matrix deep to the nail root is the region
  from which the nail growth occurs

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Nail Growth

• Nail matrix below nail root produces growth
• Cells transformed into tightly packed keratinized
  cells
• 1 mm per week

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Clubbing of the Finger Nails Symptom of
Advanced Lung Cancer
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• It takes about 8 months for a nail to grow out.
• White spots are called Leukonychia.- Caused by
  trauma, fungus, decreased zinc, decreased
  protein, alcoholism, allergy to nail products.
• Brittle nails- Decreased Iron and Biotin, thyroid
  and/or kidney disease
• Clubbed nails- hypoxia, lung cancer, heart or
  liver disease
• Spooning- Iron deficiency anemia, systemic fungal
  infections, B12 deficiency
• Beaus Lines Transverse depression- Acute sever
  illness, diabetes, chemotherapy, decreased
  calcium
• Splinter hemorrhages Red/brown linear streaks,
  bacterial endocarditis, trichinosis( parasite-raw
  food )
• Paronchyia inflammation of nail root,
  manicuring, biting, bacteria, yeast, fungi

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Excretion and Absorption

• 500 mL of water evaporates from it daily
• Small amounts salt, CO2, ammonia and urea are
  excreted
• Lipid soluble substances can be absorbed through
  the skin
• vitamins A, D, E and K, Oxygen and CO2
• acetone and dry-cleaning fluid, lead, mercury,
  arsenic, poisons in poison ivy and oak

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Transdermal Drug Administration

• Method by which drugs in a patch enter the body
• Drug absorption most rapid in areas where skin is
  thin (scrotum, face and scalp)
• Examples
• nitroglycerin (prevention of chest pain from
  coronary artery disease)
• scopolamine ( motion sickness)
• estradiol (estrogen replacement therapy)
• nicotine (stop smoking alternative)

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• In 2002 23,800 pre-mature deaths in U.S form
  cancer due to decreased UVB exposure which
  decreases the VIT D.
• Other research says 50-63,000 die a year from
  decreased Vit. D. this is higher than 8800 deaths
  from Melanoma or squamous cell carcinoma.
• 1 in 5 kids ( 80 hispanics 90 afroamericans)

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Burns

• 1st Degree Sunburn Skin redness erythema
  inflammation of the epidermis.
• 2nd Degree Entire Epidermis and some dermis-
  Blister, pain, swelling. The accessory structures
  usually not effected.
• 3rd Degree Destroys BOTH epidermis and dermis.
  Swelling but less pain b/c sensory nerves are
  destroyed with blood vessels.
• If burns cover more than 20 of the body then
  its life threatening b/c Increased fluid loss,
  evaporating cooling, bacteria on moist skin. This
  will lead to wide spread infection called SEPSIS.
  This is leading cause of death in burn victims.

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• If burns are on 80 of the body 50/50 of
  living.
• Rules of 9 for body parts and of burn
• Arms 9/9 18
• Legs 18/18 36
• Trunk 18/18 36
• Head 9 9
• Genitals 1
• ______________________
• 100

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UVA UVB Rays

• UVA-
• Penetrate the dermis
• Produces oxygen free radicals that disrupt
  collagen and elastic fibers. This is reason for
  severe wrinkling.
• Permeate blood vessels and destroys Folic Acid.
• UVB
• These rays reach the keratinocytes and convert
  cholesterol into pre-vit D, which the kidney will
  later make into vit D.
• The melanin produced protects against DNA damage
  and folate breakdown.

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Repair of the Integument

• Bleeding occurs
• Mast cells trigger inflammatory response
• A scab stabilizes and protects the area
• Germinative cells migrate around the wound
• Macrophages clean the area
• Fibroblasts and endothelial cells move in,
  producing granulation tissue

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Repair of the Integument

• Figure 514 Repair of Injury to the Integument.

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Repair of the Integument

• Figure 514 Repair of Injury to the Integument.

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Repair of the Integument

• Fibroblasts produce scar tissue
• Inflammation decreases, clot disintegrates
• Fibroblasts strengthen scar tissue
• A raised keloid may form

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Repair of the Integument

• Figure 515 A Keloid.

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Importance of the Integumentary System

• Figure 516 The Integumentary System in
  Perspective.

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Importance of the Integumentary System

• Figure 516 The Integumentary System in
  Perspective.

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Importance of the Integumentary System

• Figure 516 The Integumentary System in
  Perspective.

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Importance of the Integumentary System

• Figure 516 The Integumentary System in
  Perspective.