1. Integumentary System (Ch. 6)
Includes: Skin, hair, and nails
Called the “cutaneous” membrane, it’s the largest organ.

2. Functions of skin: -prevent excess water loss
- protective barrier from microorganisms and UV radiation

3. -production of vitamin D (needs sunlight)
-regulation of body temperature (sweat or goose bumps)

4. -excretion of waste (sweat)
-sensation of the environment
-immune response

5. Structure of skin: -contains all 4 tissue types! -3 main layers:
Epidermis
Dermis
Hypodermis

6. Epidermis- several layers of epithelium called “strata”
corneum- uppermost layer of dead cells, 4-5 layers that
produces keratin (tough, waterproof protein)
lucidum- (only in “thick skin”) – Langerhans cells
granulosum- Langerhans cells – produces immune response
spinosum- Langerhans cells
basale- where mitosis occurs, the “newest skin”
melanocytes produces the pigment melanin
Merkel cells – detect touch
Epidermis- several layers of epithelium called “strata”

7. Dermis- mostly connective tissue
(collagen - support and elastin fibers)
and highly vascular
contains the following:
-sweat glands
-sebaceous glands: produce oil (near hair follicles)
-hair follicles : epithelial “tubes” that grow hair
-hair: made of keratin (protein) & melanin (pigment)
-errector pili muscle: make hair stand up
-sensory receptors: (nerve endings)

8. Nerve ending of the skin- (cutaneous sensory receptors)
There are receptors for:
Cold
Pain
Itch
Light Touch
Hot
Tickle
Pressure

10. Hypodermis- sometimes called “subcutaneous” may contain:
loose connective tissue connecting to muscle or bone
adipose tissue for fat storage

11. Thick vs. Thin Skin Thick: Thin: Palms and soles of feet
No hair
Friction ridges (finger prints)
Only epidermis is thicker
Thin:
Covers vast majority of the body

13. Human Anatomy, 3rd edition
Fingerprints
Human Anatomy, 3rd edition
Prentice Hall, © 2001

14. Functions of Hair
Protection
Thermoregulation
Sensory

15. Nail Structure
Nail body
Free edge
Nail root
Matrix
Lunula (moon)

16. Nail Structure FG04_15.JPG Title: Structure of a Nail
Notes: These drawings illustrate the prominent features of a typical fingernail as view from the surface and in section.
Keywords: fingernail, hyponychium, nail bed, lateral nail groove, lunula, eponychium, phalanx, dermis, epidermis

17. Function of Nails
1. protecting the distal phalanx, the fingertip, and the surrounding soft tissues from injuries enhance precise delicate movements of the distal digits 3. aids in the appreciation of fine touch

18. Aging – collagen is destroyed - wrinkles

19. Keratin waterproofs your skin

20. Skin Cancer
Most skin cancers are caused by exposure to the sun.