1. Integumentary System
Accessory Structures

2. Accessory structures
Nails, hair follicles, skin glands

3. Nails Protective covering on the ends of fingers & toes
Nail plate (keratinized cells)
Nail bed
Lunula
Cells divide at lunula, pushing older cells toward tip of nail

4. Q. What is the most actively growing region of the nail?
A. Lunula

5. Fun Nail Facts Nail appearance mirrors health.
Bluish nail beds may indicate a circulatory problem
White nail beds may be due to anemia
A dark spot not related to injury may be melanoma
Horizontal furrows may indicate a period of illness or malnutrition

6. Hair Follicles
Hair grows from a tube-like depression called a hair follicle
Hair root – under the skin surface
Hair bulb – where cells are dividing
New cells push older cells up, they be come keratinized and die (this is the part you see!)

7. Hair Follicles Losing 20-100 hairs a day is normal!
A hair grows for 2-6 years then takes a break for 2-3 months
When a new hair begins to form in this follicle, the old one is pushed out

8. Q. What is the area called where hair is growing?
A. Hair bulb

9. Hair follicle Arrector pili muscle is attached to each follicle
When a person is cold, these muscles contract, causing hair to stand straight up (goose bumps)

10. Hair Follicles Hair color
Genes determine what type and how much pigment is produced by melanocytes in the follicle
Eumelanin – brownish/black
Pheomelanin – red/yellow

11. Q. What causes goose bumps?
A. The hair standing on end is caused by the arrector pili muscle contracting.

12. Skin Glands Sebaceous glands – usually associated with hair follicles
Secrete fatty material called sebum
Helps hair and skin soft, pliable, and waterproof

13. Skin Glands
Sweat glands – coils down deep into dermis or subcutaneous layer
Eccrine glands – most common
Respond to elevated body temperature
Forehead, neck, back, palms and soles
Apocrine glands – (smelly sweat)
Respond to emotions, pain, and being frightened
Armpits and groin

14. Skin Glands

15. Skin Glands Specialized sweat glands Ceruminous glands: ear wax
Mammary glands: milk

16. Q. What is the function of sebaceous glands?
A. Secrete sebum to keep hair and skin soft, pliable, and waterproof

17. Word Bank for Labeling Hair shaft Hair follicle Sebaceous gland Dermis
Subcutaneous tissue
Arrector pili muscle
Sweat gland
Blood vessels
Dpidermis