1. List four functions of the integumentary system.
Objective 4
List four functions of the integumentary system.

2. Skin Functions 1. Protects deeper tissues from:
Mechanical, Chemical, Bacterial, Thermal damage
Ultraviolet radiation
Desiccation (water-proof)
Only lipid-based substances can pass through (some drugs, poison ivy, nail polish remover, etc.)

3. Skin Functions 2. Aids in heat regulation
blood vessels swell to add heat, constrict to conserve heat
3. Aids in excretion of urea and uric acid
through sweat
4. Synthesizes vitamin D to make melatonin and other important body chemicals (“cabin fever”)

4. Objective 5
Name the tissue types composing the dermis and epidermis; including layers and functions.

5. Skin Structure Dermis (lowest layer) Dense connective tissue
Epidermis – outer layer
Stratified squamous epithelium
Often keratinized (hardened by keratin)
Figure 4.3

6. Skin Structure Deep to dermis is the hypodermis Not part of the skin
Anchors skin to underlying organs
Composed mostly of adipose tissue

7. Skin Structure
Figure 4.4

8. Dermis Two layers Papillary layer Projections called dermal papillae
Pain receptors
Capillary loops
Reticular layer
Blood vessels
Glands
Nerve receptors

9. 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)

10. 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 thick Waterproof
Last layer with capillaries/blood

11. 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…