1. Unit 3: Integumentary System
Chapter 5

2. What is integument? Accounts for 16% of body weight
Integument/Integument system: Debated as to whether or not your skin is an organ or organ system
Accounts for 16% of body weight
2 Major Components:
1-Skin or Cutaneous Membrane
Epidermis
Dermis
Hypodermis
2-Accessory Structures
Nails
Exocrine glands

3. Functions of Integumentary System
Protection
Excretion (salts, water, organic wastes)
Maintenance of body temp
Synthesis of vitamin D3
Storage of nutrients (adipocytes)
Detection of touch, pressure, pain, etc.

4. Cutaneous membrane Skin Epidermis (superficial) Dermis
Hypodermis (deep)

5. Epidermis Thin skin=made of 4 layers of stratified Squamous tissue
Most of body
Thick skin=made of 5 layers
Hands and feet

6. Made of Stratified Squamous epithelium
Layers of Epidermis
Made of Stratified Squamous epithelium
Stratum Corneum (superficial)
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale or Germinativum (deep)
Cells eventually pass through all layers or can eventually be found

8. Stratum Corneum Surface skin (most superficial)
Highly keratinized: thick, interwoven
15-30 days to get from stratum basale to stratum corneum
Stay at stratum corneum for 2 weeks b/f shed
Loose 500 mL (1 pint) water a day through skin
Blisters: water retention between dermis/epidermis under high stress

9. Stratum Lucidum Found in thick skin Glassy, tough Filled with keratin
Fibrous proteins—make up your hair and nails
Layer missing in “thin” areas

10. Stratum Granulosum “Grainy Layer” Have stopped dividing at this time
3-5 layers
Have stopped dividing at this time
High in keratin
Makes cells flatter and thinner

11. Stratum Spinosum “Spiny Layer” 8-10 layers
Langerhans Cells =participate in immune response

12. Stratum Basale Innermost Closest to basement membrane
Sends projections into dermis (below basement membrane)
Called epidermal ridges
Give skin the whorls of fingertips
Basal cells =stem cells to make more skin
Merkel Cells =sense touch where no hair is present
Melanocytes =skin tone

14. Skin Color
Due to interaction of Epidermal Pigmentation and Dermal Circulation

15. Epidermal Pigmentation
2 Pigments that control your skin color
1-Carotene (orange-yellow)
Found in stratum corneum
2-Melanin (brown, yellow-brown, black)
Found in stratum basale
protects us from UV radiation
Melanocytes produce
Dark skin = increased amount of Melanin production not increased amount of individual Melanocytes

16. Dermal Circulation Gives pale or flushed look
Better circulation =flushed
Reduced circulation=pale

17. Stop

18. Why UV-Radiation is bad!
Damages DNA of the cell, causing mutations and promoting cancer development
Read bottom of 147(Melanocytes-Dermal Circulation)

19. Why UV-Radiation is good! Vitamin D3
When exposed to sun, epidermal cells make D3, then the liver converts D3, and the kidney makes calcitriol.
Calcitriol=ability to absorb calcium and phosphorous
(no calcitriol=impaired bone maintenance and growth)

20. Epidermal Conditions Tattoo’s Freckles Birthmarks
Areas where melanocytes are producing a higher than normal rate of melanin.
Birthmarks
Non-vascular
Overgrowth of melanocytes
Tattoo’s

21. The Dermis Papillary Layer
Areolar tissue, capillaries, sensory neurons
Supplies epidermis
2. Reticular Layer
Collagen and elastic fiber

22. Wrinkles and Stretch Marks
Collagen fibers=strong, resists stretching BUT bend easily
Elastic fibers=stretch and return
=flexible, elastic dermis
Aging, hormones, and excess UV = weakened fibers  Wrinkles
Excessive stretching past fibers capabilities lead to damaged fibers=stretch marks
Caused by: pregnancy, major weight loss/gain
SOLUTION: Retin-A from vitamin A increases blood flow to dermis which increases chances for repair

23. Accessory Structures-Hair
5 million hairs
98% not on head
Hair Follicle=organ when hair is grown
Hair Root=anchors hair to skin
Hair Shaft=part you see

24. Accessory Structures-Hair
Is hair living?
No-Comprised of non-living cells
Hair follicles are
How is color determined?
Pigment produced by melanocytes
The biochemistry of these structures is affected by DNA
Hormonal/Environmental affects

25. Functions of Hair Protection (eye lashes, head, sensory, ears, nose)
Root hair plexus=sensory nerve around each hair follicle
Arrector Pilli-smooth muscle attached to hair follicle=when stimulated, contracts, causes “goose bumps”
Stimulated by emotional states, response to cold

26. Growth and Replacement of Hair
Hair growth cycle=2-5 years
.33mm/day
Hair loss occurs when the follicle becomes inactive and shrinks
Over time, the connection breaks=hair loss
The old hole sheds, new one forms

27. Hair: Real Life Application
Male Pattern Baldness
Decrease in hormones circulating in the blood
Alopecia
1 in every 100,000
Complete hair loss all over body
Genetic
Causes death of hair follicles

28. Accessory Structure-Glands in the Skin
Sebaceous (Oil Glands-Holocrine)
Share a duct with hair
Waxy, oil secretions
Apocrine Sweat Glands (armpits, around the nipples, groin)
Odorous, sticky
Through hair follicle
Begin at puberty
Merocrine Sweat Glands (all other sweat)
2-5 million
High numbers in palms/soles

29. Accessory Structure-Nails
Provides protection to finger
Nail Body cover nail bed
Production at nail root
Lunala is pale=lack of blood vessels
Is dead, tightly compressed keratin packed cells

30. The Hypodermis or subcutaneous
Not part of integument but important for stabilization
Areolar/Adipose tissue
Elastic
Area for injections