1. April 12, 2018
Journal: Explain two differences between viruses and bacteria.
HAND IN YOUR JOURNALS AFTER YOU FINISH TODAYS!

2. Integumentary System

3. Functions: Protection Keeps the body from drying out Stores fat
Produces vitamin D
Sensory input
Regulates body temperature

4. Skin Made up of 3 tissue layers: Epidermis Dermis
Subcutaneous fascia a.k.a. hypodermis

5. Epidermis Outermost layer of skin
Made up stratified squamous epithelial tissue
Contains no blood vessels or nerve cells

6. Layers of the Epidermis

7. Stratum corneum
Dead cells on the outermost surface of the skin that are shed
Flat, scaly, and keratinized epithelial cells
Protect the layers underneath from drying out

8. Stratum lucidum
Layer of dead, keratinized epithelial cells only found in parts of the body with thick skin
Ex: Palms and heels
Functions in protection from UV rays

9. Stratum granulosum
Middle layer of the epidermis where living cells are filled with keratin and begin to die

10. Stratum spinosum
Living epithelial cells that do not receive nutrients from the dermis, but divide at a slow rate
Contain Langerhans cells that aid in the immune response

11. Stratum basale
Living epithelial cells that receive nutrients from the dermis
Undergo rapid mitosis to replace lost cells
Contains melanocytes

12. Melanocytes
Produce melanin, the substance that is responsible for your skin color
More melanin = darker skin color

13. Epidermis Layer Shedding
Surface cells are constantly shedding
Cells originate in the stratum basale and are pushed upward towards the surface
As they are pushed upwards the cells die and become filled with a protein called keratin
This process takes between 2 and 4 weeks

14. Dermis Layer right below the epidermis
Thick layer of irregular connective tissue

15. Two Layers within the Dermis:
Both contain collagen and elastic fibers
Papillary Layer
Top layer of thin fibers
Contains ridges that are responsible for fingerprints
Reticular Layer
Bottom layer of thick fibers

16. Collagenous and elastic fibers
Helps your skin shift when you move
Allows skin to return to its normal shape when your body is at rest
Stretches out over time so skin loses it’s firmness and flexibility

17. Subcutaneous fascia Aka hypodermis Innermost layer of skin
Composed of fatty tissues and elastic and fibrous connective tissue
Connects to the muscles of your body

18. Lipocytes
Fat cells produce the fat needed to protect the body and to act as insulation for regulating temperature