1. Extra skin components
Skin part 2

2. Review How many layers of skin are there?
Strata is a fancy name for what feature of the epidermis?
How does the epidermis receive nutrients?
Keratinization is the process of what?

3. Review What is the major function of the elastin protein.
The stratum Basale is responsible for producing what?
In which layer would you find the stratum corneum?
What is the major function of the hypodermis?

4. Hair and Nails
Hair is composed of keratinized threads of cells that develop from the epidermis and cover most of the body.
Three components of hair:
Medulla
Cortex
Cuticle

5. Hair Medulla in the center contains sort keratin and air
Cortex the inner most portion of the hair has pigment that gives hair it’s color.
The outer layer is the cuticle and has cells that overlap like scales.
Cuticle and cortex have hard keratin.

6. Hair
The hair root in a hair follicle is embedded beneath the skin in the dermis.
Hair sheds and is replaced constantly during growth and rest phases.

7. Hair Hair serves protective functions:
Eyebrows keep sweat from running into the eyes
Nose and ear hairs filter dust from the air
Scalp hairs protect against abrasion and overexposure to sun rays.

8. Hair
The deep end of the follicle that extends into the dermis is called the hair bulb.
Papilla protrudes into the hair follicle supplying the hair with nutrients for growth.
Arrector pili muscles are smooth muscle cells attached to hair follicles.
Makes hair stand up when the contract

9. Nails Nails develop from the epidermis like skin.
Also made of keratinized cells
Nails are pink because they are translucent showing the vascular system beneath.
Nails serve as protection

10. Nails
The nail has four major components:
Lunula
Body
Root
Free edge

11. Nails Lunula is the half moon shaped part at the base of the nail.
Body and the free edge are the visible portion.
The root is hidden under skin folds.
Under the root lies the matrix.
Eponychium thin layer of epithelium covers the nail during development.
The hyponychium is the epithelium of the nail bed.

12. Recap Vocabulary to know Keratinized Follicle Root Lunula Medulla
Cortex
Cuticle