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1 Integumentary Integumentary System System – Skin Skin Layers Layers Divisions of the Integumentary Divisions of the Integumentary System System The integumentary system is composed of the The integumentary system is composed of the skin and it’s accessory organs. skin and it’s accessory organs. The skin has three distinct layers. The skin has three distinct layers. Epidermis Epidermis Dermis Dermis Subcutaneous fat or hypodermis. Subcutaneous fat or hypodermis. Divisions of the Integumentary Divisions of the Integumentary System System Accessory organs. Accessory organs. Hair, Nails, and Glands (sweat and oil). Hair, Nails, and Glands (sweat and oil). All of the accessory organs are based and formed All of the accessory organs are based and formed from epidermis, although they are located in the from epidermis, although they are located in the dermis. dermis. General Facts General Facts The skin has a surface area of between 1.5 and The skin has a surface area of between 1.5 and 2.0 square meters. 2.0 square meters. The skin weighs 4 The skin weighs 4-5 kg (9 5 kg (9-11 lbs). 11 lbs). Each cm Each cm 2 of skin contains: of skin contains: 70cm of blood vessels. 70cm of blood vessels. 55cm of nerves 55cm of nerves 100 sweat glands 100 sweat glands 15 oil glands 15 oil glands 230 sensory receptors. 230 sensory receptors. Skin Structure page Skin Structure page 153 (This is on 153 (This is on pg 4 of notes pg 4 of notes – You need know all You need know all of your diagrams! of your diagrams! Figure 4.4 Begin pgs 5 Begin pgs 5-6 of notes 6 of notes Look at diagrams carefully to see Look at diagrams carefully to see which layer the information is which layer the information is referring to. Remember: Structure referring to. Remember: Structure determines Function! determines Function!

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  • 1

    Integumentary Integumentary

    System System Skin Skin

    LayersLayers

    Divisions of the Integumentary Divisions of the Integumentary

    SystemSystem

    The integumentary system is composed of the The integumentary system is composed of the

    skin and its accessory organs.skin and its accessory organs.

    The skin has three distinct layers.The skin has three distinct layers.

    EpidermisEpidermis

    DermisDermis

    Subcutaneous fat or hypodermis.Subcutaneous fat or hypodermis.

    Divisions of the Integumentary Divisions of the Integumentary

    SystemSystem

    Accessory organs.Accessory organs.

    Hair, Nails, and Glands (sweat and oil).Hair, Nails, and Glands (sweat and oil).

    All of the accessory organs are based and formed All of the accessory organs are based and formed

    from epidermis, although they are located in the from epidermis, although they are located in the

    dermis.dermis.

    General FactsGeneral Facts

    The skin has a surface area of between 1.5 and The skin has a surface area of between 1.5 and

    2.0 square meters.2.0 square meters.

    The skin weighs 4The skin weighs 4--5 kg (95 kg (9--11 lbs).11 lbs).

    Each cmEach cm22 of skin contains:of skin contains:

    70cm of blood vessels.70cm of blood vessels.

    55cm of nerves55cm of nerves

    100 sweat glands100 sweat glands

    15 oil glands15 oil glands

    230 sensory receptors.230 sensory receptors.

    Skin Structure page Skin Structure page 153 (This is on 153 (This is on pg 4 of notes pg 4 of notes You need know all You need know all

    of your diagrams!of your diagrams!

    Figure 4.4

    Begin pgs 5Begin pgs 5--6 of notes6 of notes

    Look at diagrams carefully to see Look at diagrams carefully to see

    which layer the information is which layer the information is

    referring to. Remember: Structure referring to. Remember: Structure

    determines Function!determines Function!

  • 2

    Epidermis Epidermis page 6 of notes page 6 of notes -- fill in fill in

    text box on left side of diagramtext box on left side of diagram

    Slide Slide

    4.10a4.10a

    Epidermis outer layer color code brackets

    Thick keratinized stratified squamous epithelium (4 or 5 layers)

    Avascular (hardened by keratin)

    Renews itself ~ every 35 - 45 days

    Has 4 distinct cell types

    Need to know this slide!

    Dust Mites Dust Mites eat your dead eat your dead

    keratinocyteskeratinocytes

    Epidermis Epidermis cell cell types types Go to page 5 Go to page 5 of notes & fill in cell info (upper right)of notes & fill in cell info (upper right)

    Keratinocytes

    Makes ups majority of epidermal cells

    produce keratin waterproofing proteinWhy important? To keep you from gaining/losing water

    Originate in deeper layers & get pushed to surface becomes keratin filled & dies

    Reminder: Connected to each other by desmosomes & tight junctions

    Cell production & keratinization are accelerated in areas of friction

    Callus thickened skin for protection

    Epidermis Epidermis cell cell types types pg 5pg 5 Melanocytes

    Found in the stratum basale Produce melanin (gives us skin color)

    which accumulates on superficial

    (between nucleus & sun) side of nucleus

    Why that location? to prevent DNA

    mutation from the UV radiation

    Mutation can change growth

    instructions & cause cancer

    MelanocytesMelanocytes

    All people have ~ the same number of All people have ~ the same number of

    melanocytesmelanocytes..

    Skin coloring differences are due to Skin coloring differences are due to

    melanocytemelanocyte activity, or the rate of melanin activity, or the rate of melanin

    catabolism within catabolism within keratinocyteskeratinocytes

  • 3

    Epidermal CellsEpidermal Cells

    Langerhans cells are formed in the bone Langerhans cells are formed in the bone

    marrow and migrate to the epidermis.marrow and migrate to the epidermis.

    These starThese star--shaped cells are macrophage that shaped cells are macrophage that

    help to activate the immune system.help to activate the immune system.

    Macrophage are cells that phagocytize foreign Macrophage are cells that phagocytize foreign

    materials (like pacmaterials (like pac--man).man).

    Epidermal CellsEpidermal Cells

    Merkel Cells. These cells are found at the Merkel Cells. These cells are found at the

    epidermal/dermal junction and are associated epidermal/dermal junction and are associated

    with sensory nerve endings. The combination with sensory nerve endings. The combination

    of a merkel cell and a nerve ending is called a of a merkel cell and a nerve ending is called a

    Merkel disc, and act as a sensory receptor for Merkel disc, and act as a sensory receptor for

    touch.touch.

    Label the 5 strata on page 5 left Label the 5 strata on page 5 left

    sideside

    5 5 epidermal strata (layers)epidermal strata (layers)

    place info on page 5 right sideplace info on page 5 right side

    From DEEP TO SUPERFICIALDEEP TO SUPERFICIALDEEP TO SUPERFICIALDEEP TO SUPERFICIAL Stratum basale

    Most important layer highly mitotic Approx. 25% melanocytes Attached to dermis along a wavy border

    Stratum Stratum spinosumspinosum

    WebWeb--like system of filaments made of bundles like system of filaments made of bundles of keratinof keratin

    Several layers thickSeveral layers thick

    Slightly mitoticSlightly mitotic

    Contains Contains LangerhansLangerhans macrophagesmacrophages

  • 4

    5 strata of the Epidermis5 strata of the Epidermis

    Stratum granulosum

    3-5 cell layers thick

    Keratinocytes flatten & lose organelles

    Also contains Langerhans cell

    contains keratin granules-major factor in slowing water loss from epidermis

    Stratum Stratum lucidumlucidum

    found in thicker epidermis found in thicker epidermis palms, palms, soles, callussoles, callus

    Few rows of clear, flattened, DEAD Few rows of clear, flattened, DEAD keartinocyteskeartinocytes

    5 strata of the Epidermis5 strata of the Epidermis Stratum corneum

    Also completely keratinized (& dead)

    Outer most layer 20-30 cells thick

    Accounts for of the epidermal thickness

    Tough (protects from abrasions & penetration), also waterproofing protection

    AGAIN: Why is waterproofing important?

    Average people shed 18 kg (40 lbs) in a lifetime

    How it all fits togetherHow it all fits together

    Dermis Dermis back to page 6back to page 6

    Left side: Strong, flexible CT - 2 layers

    Semi-fluid matrix with many collagen, elastin, & reticular fibers

    Cells found in dermis:

    Fibroblast form connective fibers

    Macrophage phagocytic cells

    Mast cells immune cells, detect foreign material

    White blood cells immune cells

    Right side Right side -- Papillary dermisPapillary dermis

    Contains Contains areolarareolar CTCT

    Dermal papillae Dermal papillae indent into the indent into the epidermis epidermis form fingerprintsform fingerprints

    What else is important about these? What else is important about these? Give us grip !Give us grip !

    Also contain Also contain

    nerve receptors,nerve receptors,

    Lots of blood vesselsLots of blood vessels

    Dermis Dermis back to page 6back to page 6

  • 5

    Blister: add in margin pg 6Blister: add in margin pg 6

    Dermal Dermal epidermal junctionepidermal junction

    Held together by Held together by desmosomesdesmosomes

    Blister Blister -- separation due to mechanical stressseparation due to mechanical stress

    What What 2 2 sublayerssublayers actually separateactually separate? Think about this!!? Think about this!!

    DermisDermis

    Page 6 - right side

    Reticular Dermis 80% of dermis

    Reticular CT & Dense irregular CT also contains Blood vessels, Nerve receptors, Glands

    cleavage lines direction of fibers in collagen bundles used in plastic surgery to reduce scarring

    flexure lines dermis secured to hypodermis

    Obvious dermal folds located around the joints that allow skin to fold when joints move

    stretch marks dermal tears

    Cleavage linesCleavage lines DermisDermis

    Hypodermis Hypodermis pg 6 left sidepg 6 left side

    Slide Slide

    4.10b4.10b

    Deep to dermis is the hypodermis -superficial fascia

    Anchors skin to underlying organs, shock absorption, insulation

    Composed mostly of adipose tissue

    Very vascular

    Site of subcutaneous injections

    5 Tissues5 Tissues

    There have been 5 types of tissues during the There have been 5 types of tissues during the

    previous slidesprevious slides

    Find the 5 types & write them in the margin on Find the 5 types & write them in the margin on

    page 6: You will need to MEMORIZE the page 6: You will need to MEMORIZE the

    location/function/slide of these 5 for this unit location/function/slide of these 5 for this unit

    testtest