1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Objective 5 Name the tissue types composing the dermis and epidermis; including layers and functions.

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Structure  Epidermis – outer layer  Stratified squamous epithelium  Often keratinized (hardened by keratin)  Dermis  Dense connective tissue Figure 4.3

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Structure  Deep to dermis is the hypodermis  Not part of the skin  Anchors skin to underlying organs  Composed mostly of adipose tissue

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layer of Epidermis  Stratum basale (“base” – deepest layer)  Cells undergoing mitosis  Lies next to dermis  Stratum spinosum  Web-like system of filaments  Stratum granulosum  3-5 layers thickWaterproof  Last layer with capillaries/blood

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layer of Epidermis  Stratum lucidum  Occurs only in thick skin  Clear, flat dead cells  Stratum corneum – only layer you can see!  Shingle-like dead cells  75% of the epidermis  Protection  “Beauty is Only Skin Deep?” …  All we see are dead cells!!! HAHAHAHA…

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Melanin  Pigment (melanin) produced by melanocytes  Color is yellow to brown to black  Melanocytes are mostly found in the stratum basale  Amount of melanin produced depends upon genetics and exposure to sunlight (tanning)

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Dermis  Two layers  Papillary layer  Projections called dermal papillae  Pain receptors  Capillary loops  Reticular layer  Blood vessels  Glands  Nerve receptors

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Structure Figure 4.4