integumentary system - skin layers integumentary system system – skin skin layers divisions of the...

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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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Page 1: integumentary system - skin layers Integumentary System System – Skin Skin Layers Divisions of the Integumentary System The integumentary system is composed of the skin and it’s

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 it’s accessory organs.skin and it’s 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!

Page 2: integumentary system - skin layers Integumentary System System – Skin Skin Layers Divisions of the Integumentary System The integumentary system is composed of the skin and it’s

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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 protein•Why 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

Page 3: integumentary system - skin layers Integumentary System System – Skin Skin Layers Divisions of the Integumentary System The integumentary system is composed of the skin and it’s

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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 Langerhan’sLangerhan’s macrophagesmacrophages

Page 4: integumentary system - skin layers Integumentary System System – Skin Skin Layers Divisions of the Integumentary System The integumentary system is composed of the skin and it’s

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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 ¾ 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

Page 5: integumentary system - skin layers Integumentary System System – Skin Skin Layers Divisions of the Integumentary System The integumentary system is composed of the skin and it’s

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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