Integumentary System – Skin Layers Updated by S. Mendoza 8/2013 Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Skin Structure page 101 (This is on pg 4 of notes – You need know all of your diagrams! Figure 4.4 Slide 4.13b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Begin pgs 5-6 of notes Look at diagrams carefully to see which layer the information is referring to. Remember: Structure determines Function!

Epidermis – page 6 of notes - fill in text box on left side of diagram Epidermis – outer layer – color code brackets Keratinized stratified squamous epithelium Avascular (hardened by keratin) Renews itself ~ every 35 - 45 days Need to know this slide! Slide 4.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Dust Mites – eat your dead keratinocytes

Epidermis – cell types – Go to page 5 of notes & fill in cell info (upper right) Keratinocytes 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 Slide 4.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Keratinocyte Growth

Epidermis – cell types – pg 5 Melanocytes Produce melanin 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 Slide 4.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Melanocytes

Label the 5 strata on page 5 left side

From deep to superficial Stratum basale highly mitotic 5 epidermal strata– place info on page 5 right side From deep to superficial Stratum basale highly mitotic Approx. 25% melanocytes Stratum spinosum Slightly mitotic Contains Langerhan’s macrophages Slide 4.10a

5 strata of the Epidermis Stratum granulosum Also contains Langerhans cell contains keratin granules Stratum lucidum found in thicker epidermis – palms, soles, callus Completely keratinized (and dead!) Slide 4.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

5 strata of the Epidermis Stratum corneum Also completely keratinized (& dead) Tough, waterproofing protection AGAIN: Why is waterproofing important? Slide 4.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

How it all fits together

Dermis – back to page 6 Left side: Strong, flexible CT - 2 layers Right side - Papillary dermis Contains areolar CT Dermal papillae – indent into the epidermis – form fingerprints What else is important about these? Give us grip ! Also contain nerve receptors, capillary loops etc. Slide 4.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Blister: add in margin pg 6 Dermal – epidermal junction Held together by desmosomes Blister - separation due to mechanical stress What 2 sublayers actually separate? Think about this!!

Dermis Page 6 right side Reticular 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 stretch marks – dermal tears Slide 4.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cleavage lines

Dermis

Hypodermis – pg 6 left side 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 Slide 4.10b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

5 Tissues There have been 5 types of tissues during the previous slides Find the 5 types & write them in the margin on page 6: You will need to MEMORIZE the location/function/slide of these 5 for this unit test