1. Unit 4: Integumentary System
SKIN!

2. Skin Info. Functions (5 major) Protection Physical barrier
Accounts for 15% of total body weight
Includes smaller accessory organs
Hair, glands, receptors, blood vessels
Functions (5 major)
Protection
Physical barrier
Regulation of body temperature
Insulation, sweat glands, blood supply
Communication
Sensory receptors→ react to stimuli
Excretion of wastes
Sweat glands
Vitamin D production

3. Three Layers Epidermis Origin of accessory organs Dermis
Where most accessory organs are located
Dense irregular connective tissue and blood vessels
Hypodermis (subcutaneous tissue)

4. Epidermis Tough protective layer Contains MELANIN
Protects from the sun, gives skin its color
It is composed of five layers of cells...

5. Epidermis SURFACE Stratum corneum Stratum lucidum Stratum granulosum
Stratum spinosum
Stratum basale
DEEP

6. Epidermis Stratum corneum The most superficial layer
20-50 rows or flattened, dead cells
Normal wear and tear sheds these cells often
Each “cell” contains KERATIN
Important in water retention
Keratin is mostly insoluble in water

7. Epidermis Stratum lucidum Only in thick skin Palms or hands
Soles of feet
3-4 rows of flattened, dead cells, mostly transparent

8. Epidermis Stratum granulosum 3-5 rows of partially flattened cells
Cytoplasm contains small granules
Proteins turning into keratin

9. Epidermis Stratum spinosum Multiple layers of cuboidal cells
Molecular bridges
Spiny or prickly appearance
Early signs of cell death
No nutrients/oxygen from diffusion

10. ***No blood supply in the epithelial tissue/epidermis!***
Stratum basale
Deepest layer
Single layer of columnar cells
Actively dividing (alive cells)
New cells pushed to surface
Die as they get farther away from blood supply in the dermis
***No blood supply in the epithelial tissue/epidermis!***
(avascular)

12. Building diagram of the skin… starting with epidermis
Draw the outline for a model of the skin to show the 3 layers:
Epidermis
Dermis
Hypodermis
*draw it big, leaving plenty of space in each layer

13. Fill in the details for the Epidermis
Diagram the details of the epidermis:
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
For each layer:
Draw the layer on your diagram
Short sentence about the structure of the layer
Indicate amount of blood flow
Short sentence about any special molecules or functions

14. Dermis Made of connective tissue Vascular
Blood vessels supply dermis with nourishment and remove waste
Blood vessels supply the stratum basale (to support constant mitosis)
*NOTICE: blood vessels don’t extend into the layers of epidermis*

15. Dermis Divided into two layers: Papillary Region - superficial
Reticular Region - deep

16. Dermis - Papillary Region
Loose, areolar connective tissue
“Friction ridges” between dermis and epidermis strengthen the connection between the dermis and epidermis
Created by projections originating in the papillary region called papillae
DNA determines friction ridge patterns -- basis for unique fingerprints!

17. Dermis - Reticular Regions
Deep to the papillary region
Dense irregular connective tissue
Many protein fibers!
Strength, elasticity, extensibility
Fibers change in response to aging, too much sun = wrinkles!!!

18. Fill in the details for the Dermis
Diagram the details of the dermis:
Papillary Region
Show the friction ridges
Label the type of connective tissue
Reticular Region
Sketch out the dense irregular connective tissue

19. Hypodermis Deep to the dermis Connects dermis to deeper body structure
Adipose tissue and loose connective tissue
Insulation (amount varies by area)
shock - absorbing

20. Fill in the details for the hypodermis
Draw in the adipose tissue
Write a short few sentences about the function of the hypodermis