integumentary system - skin layers integumentary system system – skin skin layers divisions of the...
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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!
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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 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
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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 LangerhansLangerhans macrophagesmacrophages
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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 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
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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