Integumentary System

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Integumentary System Body Membranes

• EQ How does the structure of the integumentary
  system relate to its functional role in
  protecting the body maintaining homeostasis?

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GPS

• SAP2. Students will analyze the interdependence
  of the integumentary, skeletal, and muscular
  systems as these relate to the protection,
  support and movement of the human body.
• a. Relate the structure of the integumentary
  system to its functional role in protecting the
  body and maintaining homeostasis.

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Body Membranes

• Function of body membranes
• Cover body surfaces epithelial tissue
• Line body cavities epithelial tissue
• Form protective sheets around organs connective
  tissue

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Classification of Body Membranes

• Epithelial membranes
• Cutaneous membranes
• Mucous membranes
• Serous membranes
• Connective tissue membranes
• Synovial membranes

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Cutaneous Membrane

• Cutaneous membrane skin
• Dry membrane
• Outermost protective boundary
• Superficial epidermis is composed of keratinized
  stratified squamous epithelium
• Underlying dermis is mostly dense connective
  tissue

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Mucous Membranes

• Surface epithelium type depends on site
• Stratified squamous epithelium (mouth, esophagus,
  vagina, anus, nose, ears, eyes)
• Simple columnar epithelium (rest of digestive
  tract, upper respiratory tact)
• Underlying loose connective tissue (AKA lamina
  propria)
• Lines all body cavities that open to the exterior
  body surface
• Often adapted for absorption or secretion

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Serous Membranes

• Surface- simple squamous epithelium
• Underlying layer-thin layer of areolar connective
  tissue
• Lines open body cavities that are closed to the
  exterior of the body
• Serous membranes- 2 layers separated by serous
  fluid-
• 1. Visceral layer ( inner layer) covers the
  outside of the organ.
• 2. Parietal layer (outer layer) lines a portion
  of the wall of ventral body cavity.

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Serous Membranes

• Specific serous membranes
• Peritoneum (parietal visceral)
• Abdominal cavity
• Pleura (parietal visceral)
• Around the lungs
• Pericardium (parietal visceral)
• Around the heart

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Connective Tissue Membrane

• Synovial membrane
• Connective tissue only
• Lines fibrous capsules surrounding joints
• Secretes a lubricating fluid called synovial
  fluid (which may become inflamed/ infected)

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Integumentary System

• Skin (cutaneous membrane)
• Skin derivatives (accessory organs/ appendages)
• Sweat glands (sudoriferous glands)
• Oil glands (sebaceous glands)
• Ear glands (ceruminous glands)
• Hair
• Nails

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Functions

• 1. Protection from
• physical/mechanical injury
• pathogen entry
• Chemical prevention of pathogen entry-acid pH
• UV radiation
• Drying out/ dessication
• 2. Sensation
• 3. Thermoregulation

• 4. Metabolic functions- Aids in excretion of
  waste- urea/ uric acid
• 5. Make vitamin D

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2 main Skin Layers

1. Epidermis- top layer
2. Dermis- middle
3. Hypodermis (Subcutaneous Layer (SubQ/SQ))- not a
   real part of skin layer of fat.

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Skin Layers

• Epidermisouter/ superficial layer
• Stratified squamous epithelium
• keratinized (hardened by keratin protein)
• .07-.12 mm thick/ 4-5 cell layers
• avascular
• 4 main cell types
• Keratinocytes-make keratin, a protein which
  replaces cell contents and protects skin
  (Structure)
• Merkel Cells- (nerve cells/ sensation)
• Melanocytesproduce melanin, a black brown
  pigment which protects us against UV light
  (pigment)
• Langerhans cells respond to microbes (immunity)

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Skin Layers

• 2. Dermis
• Dense fibrous CT
• Some areolar CT
• Highly vascularized
• Contain all the skin accessory structures
• 2 layers (papillary reticular)

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Skin Structure

• 3. Subcutaneous tissue (hypodermis) is deep to
  dermis (Not real part of the skin)
• Made up of lipids/ fats- fatty layer
• Anchors skin to underlying organs
• What type of connective tissue is this?
• What role/ function do you think this layer serve?

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Layers of the Epidermis

• Stratum basale (stratum germinativum)
• Deepest layer
• Attached to dermis via basement membrane.
• highly mitotic w/ rapid regeneration rate
• Daughter cells are pushed upward to become the
  next layer above it (more superficial layers)

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Layers of the Epidermis

• 2. Stratum spinosum
• 2nd deepest layer
• 8-10 cell layers thick
• Lower mitotic rate
• Make keratin as cessl get pushed up.
• AKA spiny/ prickly layer- b/c when they beign to
  shrink, the desmosomes connecting adjacent cells
  look like spikes.
• Recall What are desmosomes what do they do?

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Do you see the spines?
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Layers of the Epidermis

• 3. Stratum granulosum
• 3-5 cell layers thick
• Cells begin to flatten die out.
• Contains keratin a waterproofing protein
• ( if water cant diffuse upward, how would the
  cells above this layer receive nutrients? What
  would happen to them?)

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Layers of the Epidermis

• 4. Stratum lucidum
• 3-5 cell layers of flat, dead keratinocytes
• Formed from dead cells of the deeper strata
  (layer)
• Occurs only in thick, hairless skin of the palms
  of hands and soles of feet
• Gives palms/ soles it light color.

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Layers of the Epidermis

• 5. Stratum corneum
• 20-30 layers of flat, keratinized, dead cells.
• toplayer of epidermis (most superficial)
• Shingle-like dead cells are filled with keratin
  (tough, protective protein prevents water loss
  from skin)
• AKA cornified layer
• (What type of tissue make up this layer?)
• (Why do you think the cells died out the farther
  they move up? How do cells in the epidermis get
  their nutrients?)

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Skin Color

• Due to 3 pigments
• Melanin
• Carotene
• Hemoglobin

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Melanin

• Pigment (melanin) produced by melanocytes
• Melanocytes are mostly in the stratum basale
• Color is yellow to reddish-brown to black
• All people have the same of melanocytes,
  individual variation in skin color due to how
  much what types of melanin is made.
• Amount of melanin produced depends upon genetics
  and exposure to sunlight
• Protects DNA from UV damage from sun

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Carotene

• Carotene
• yellow- to orange pigment in plants not made by
  humans/ animals.
• (how do you think it gets in our skin
  contribute to color?)
• When large amts are eaten, it can deposit in the
  stratum corneum of thick thin. (Which layer is
  that)?
• Temporary.

• Hemoglobin
• Pigment produced in blood cells that transport
  oxygen.
• Visible in fair-skinned individuals when blood
  rushes to surface of skin.

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Dermis

• Overall dermis structure
• Collagen elastic fibers located throughout the
  dermis
• Collagen fibers give skin its toughness
• Elastic fibers give skin elasticity
• Blood vessels play a role in body temperature
  regulation (HOW?)

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Dermis- 2 layers

• Papillary layer (upper 1/5 of dermal region)
• Projections called dermal papillae
• Some contain capillary loops
• pain receptors touch receptors
• Loose (areolar) CT
• Form ridges of fingerprints
• Lots of blood vessels- (constrict in cold, dilate
  in warm weather-WHY?)
• Sweat oil glands
• Deep pressure / sensory receptors

• 2. Reticular layer (deepest skin layer- lower 4/5
  of dermis)
• Dense irregular CT
• (What type of fibers does this layer of CT
  contain?
• What properties will this fiber-type confer to
  this layer? How does this help the skin?)
• Contain majority of accessory structures

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Dermal Papillae Reticular layer
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Skin Structure
Figure 4.4
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Subcutaneous Tissue/ Hypodermis

• A.k.a. the hypodermis or the superficial fascia.
• Deep to the dermis.
• Consists of primarily adipose tissue plus some
  areolar connective tissue.
• Stores energy, provides insulation padding.
• Anchors the skin to underlying structures,
  especially muscles.
• Different distribution btwn the sexes.

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Skin Appendages/ Accessory Structures

• Cutaneous glands are all exocrine glands (What
  does this means)?
• Sebaceous (oil) glands
• Sudoriferous (sweat) glands
• Ceruminous (ear) glands
• Hair/ hair follicles
• Nails

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4
2
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Sebaceous (oil) glands

• Produce oily, lipid-rich
• secretion called sebum.
• Lubricates softens skin
• Prevents brittle hair
• Decreases skin permeability
• to water
• Kills bacteria (bactericidal)
• Most have ducts that empty into hair follicles
  others open directly onto skin surface
• Glands are activated at puberty (How is this
  related to acne in teens? Why dont kids get
  acne?)
• Found everywhere except palms soles

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Appendages of the Skin
Figure 4.6a
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The sebaceous gland is indicated by the arrow.
Note how its duct is unbranched and how it
empties into a hair follicle.
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Sudoriferous (sweat) glands

• Produce sweat
• Widely distributed in skin- except nipples part
  of external genitalia.
• gt 2.5 million/person
• Two types
• Eccrine (Merocrine) sweat glands
• Apocrine sweat glands
• Ducts empty into hair follicles

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Sweat and Its Function

• Composition
• Mostly water
• Salts (mostly NaCl) and vitamin C, lactic acid
• Some metabolic waste urea, uric acid, ammonia
• Fatty acids and proteins (more in apocrine)
• Function
• Helps dissipate excess heat (how does this help
  maintains homeostasis?)
• Excretes waste products

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Eccrine sweat glands

• More numerous than apocrine glands
• Prominent on the palms, soles forehead
• Ducts empty in pores on skin surface
• Major function is to cool the body-
  thermoregulation.
• Mostly water salts (mainly NaCl)
• Acid pH of 4-6 acid environment kills bacteria
  (i.e. chemical protection)

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Apocrine sweat glands

• Located in axillary, pubic, anal regions.
• Larger thicker than eccrine glands.
• Ducts empty into hair follicle, not directly
  through pore.
• Contain more lipids proteins- when degraded by
  bacteria a foul, sometimes musty odor is formed.
• Milky or yellow in color.
• Active during puberty
• Secretes during times of pain, stress sexual
  activity.
• No role in thermoregulation.
• (What causes the yellow stains you sometimes see
  on t-shirt in the underarm area?)
• (What causes the musty odor?)

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Ceruminous glands

• Modified apocrine glands in the inner lining of
  the external ear canal.
• Secretes a sticky waxy substance called cerumen
  (earwax). It combines w/ sebum dead epidermal
  cells to form a bitter compound that offers a
  barrier to entry of the ear.
• How does this keeps your
• ear germ-free?

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Appendages of the Skin- HAIR

• Hair is a flexible strand made of highly
  keratinized dead cells.
• The keratin in both hair nails is hard keratin,
  a stiffer, more compact version of the soft
  keratin that dominates the epidermis. It is
  tougher its cells do not individually flake
  off.
• The hair is made by the living hair follicle.
• Melanocytes provide pigment for hair color.
• Found all over except- palms, soles,
• nipples, lips.

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HAIR

• The hair consists of 3 concentric regions
• Medulla ? the innermost region consisting of
  large cells and air spaces.
• Cortex ? surrounds the medulla and consists of
  flattened keratinized cells
• Cuticle ? outer layer of flat keratinized cells
  that overlap like shingles with their free edges
  pointing upward.

Figure 4.7b
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HAIR
Figure 4.7c
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Hair and Hair Follicles

• Hair Follicle Dermal and epidermal sheath
  surround hair root.
• Wrapped around the bulb of the follicle is a
  network of sensory nerve endings known as the
  hair root plexus. Allow the hairs to serve a
  sensory function.
• Attached to each hair is a bundle of smooth
  muscle known as an arrector pili muscle. In
  times of fright or cold, these muscles contract
  and cause the hair to stand on end and produces
  goose bumps.
• (Increases airflow in mammals with significant
  hair (i.e., not humans) and increases the
  apparent size of an animal with significant hair.
  Vestigial function in humans).

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HAIR
Figure 4.7a
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Notice the hair shaft, hair follicle, papilla,
and the multiple sebaceous glands. Where is the
epidermis?
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HAIR
Figure 4.8
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Notice the 3 layers of the hair itself.
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NAILS

• Scale-like modifications of the epidermis
• Heavily keratinized dead (hard keratin) cells
• Stratum basale extends beneath the nail bed
• Responsible for growth
• Lack of pigment makes them colorless. (What
  protein is lacking)? (Why do nails look pink?)
• (What structure does the nails correspond to in
  cow, horses, birds, etc.)?

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NAIL

• Nail structures
• Free edge
• Body- is the visible attached portion
• Root- embedded in skin
• Nail folds- skin folds form from overlapping
  cells.
• Cuticle- is the proximal nail fold that projects
  onto the nail body

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NAIL

1. Nail bed- extension of the stratum basale beneath
   the nail.
2. Nail matrix- thicken proximal are of nail bed
   causes nail growth.
3. Lunula- crescent- thicken, white crescent at
   base of nail.

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Appendages of the Skin
Figure 4.9
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Skin Homeostatic Imbalances

• Imbalance in homeostasis is often revealed in the
  skin. More than 100 different skin conditions.
• Allergies, bacterial, viral or fungals infection.
• Burns
• cancer
• Infections
• Athletes foot (tinea pedis)
• Caused by fungal infection
• Boils and carbuncles
• Caused by bacterial infection
• Cold sores
• Caused by virus

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Skin Homeostatic Imbalances

• Infections and allergies
• Contact dermatitis
• Exposures cause allergic reaction
• Impetigo
• Caused by bacterial infection (Staph)
• Psoriasis
• Cause is unknown
• Triggered by trauma, infection, stress

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Skin Homeostatic Imbalances
Figure 4.10
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Skin Homeostatic Imbalances

• Burns
• Tissue damage and cell death caused by heat,
  electricity, UV radiation, or chemicals
• Associated dangers
• Dehydration
• Electrolyte imbalance
• Circulatory shock

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Rule of Nines

• Way to determine the extent of burns
• Body is divided into 11 areas for quick
  estimation
• Each area represents about 9 of total body
  surface area

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Rule of Nines
Figure 4.11a
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Severity of Burns

• First-degree burns
• Only epidermis is damaged
• Skin is red and swollen
• Second-degree burns
• Epidermis and upper dermis are damaged
• Skin is red with blisters
• Third-degree burns
• Destroys entire skin layer
• Burn is gray-white or black

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Severity of Burns
Figure 4.11b
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Critical Burns

• Burns are considered critical if
• Over 25 of body has second-degree burns
• Over 10 of the body has third-degree burns
• There are third-degree burns of the face, hands,
  or feet

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Skin Cancer

• Cancerabnormal cell mass
• Classified two ways
• Benign
• Does not spread (encapsulated)
• Malignant
• Metastasized (moves) to other parts of the body
• Skin cancer is the most common type of cancer

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Skin Cancer Types

• Basal cell carcinoma
• Least malignant
• Most common type
• Arises from stratum basale

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Skin Cancer Types
Figure 4.12a
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Skin Cancer Types

• Squamous cell carcinoma
• Metastasizes to lymph nodes if not removed
• Early removal allows a good chance of cure
• Believed to be sun-induced
• Arises from stratum spinosum

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Skin Cancer Types
Figure 4.12b
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Skin Cancer Types

• Malignant melanoma
• Most deadly of skin cancers
• Cancer of melanocytes
• Metastasizes rapidly to lymph and blood vessels
• Detection uses ABCD rule

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Skin Cancer Types
Figure 4.12c
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ABCD Rule

• A Asymmetry
• Two sides of pigmented mole do not match
• B Border irregularity
• Borders of mole are not smooth
• C Color
• Different colors in pigmented area
• D Diameter
• Spot is larger then 6 mm in diameter