1. Integumentary system
Sept

2. What do you already know about the integumentary system?

3. Integumentary System Components:
Skin (aka cutaneous membrane or integument)
Hair
Nails

4. Integumentary System Components:
Skin (aka cutaneous membrane or integument)
Hair
Nails
Fun fact:
The skin is the largest organ in the body.
The skin of an average adult weighs more than 9 lbs!

5. Integumentary System Functions Protection Thermoregulation
Excretion of wastes
Synthesis of vitamin D

6. Functions of Integumentary System
Protection
From mechanical, chemical, and thermal damage
Barrier of tough, keratinized cells
Pain receptors warn body of possible damage
From pathogens
Unbroken surface
Acidic secretions inhibit bacterial growth
Phagocytes ingest foreign material
From UV radiation
Melanin absorbs UV light and prevents it from reaching deeper layers
From desiccation (drying out)
Keratin and other substances keep skin fairly waterproof

7. Functions of Integumentary System
Thermoregulation
How does the skin help us cool down?
How does the skin help us warm up?

8. Functions of Integumentary System
Thermoregulation
How does the skin help us cool down?
Evaporative cooling (sweating)
Increased blood flow through skin (increases heat loss)
How does the skin help us warm up?
Goose bumps: arrector pili muscles contract to pull hair upright, and add insulation to body
Decreased blood flow through skin (reduces heat loss)

9. Functions of Integumentary System
Excretion of wastes –
The sweat glands excrete metabolic wastes (urea, uric acid), salt, and lactic acid (in addition to water)
Synthesis of vitamin D
When UV light hits the skin, modified cholesterol molecules are converted into vitamin D.
Calcium can only be absorbed in the digestive tract if vit D is present. Liver and kidney also play a role in final conversion to active form of vitamin.

10. Quick Review Turn & Talk (5 min), then share with class.
Scholar on left …
Name the four major functions of the integumentary system.
Explain how the skin fights pathogens.
Scholar on the right …
Name the three components of the integumentary system.
Explain how the skin allows us to thermoregulate.
Calcium can only be absorbed in the digestive tract if vit D is present. Liver and kidney also play a role in final conversion to active form of vitamin.

11. Skin Structure The skin is composed of two layers: Epidermis – made of
_______________
tissue
2) Dermis-
Calcium can only be absorbed in the digestive tract if vit D is present. Liver and kidney also play a role in final conversion to active form of vitamin.

12. Skin Structure The skin is composed of two layers: Epidermis – made of
epithelial
tissue
2) Dermis-
made of dense
connective
Hypodermis is NOT skin. Composed of adipose tissue. Helps anchor skin, & cushion and insulate deeper tissues

13. Skin Structure
Fun fact: Blisters occur when friction causes the epidermis to pull away from the dermis.
Hypodermis is NOT skin. Composed of adipose tissue. Helps anchor skin, & cushion and insulate deeper tissues

14. Epidermis Structure Epidermis is made of epithelial tissue.
Quick Review:
What are the characteristics of epithelial tissue?

15. Epidermis Structure Epidermis is made of epithelial tissue.
Quick Review:
What are the characteristics of epithelial tissue?
Form continuous sheets, have cell junctions
Avascular
Apical side free
Other side attached to basement membrane
Regeneration
Hypodermis is NOT skin. Composed of adipose tissue. Helps anchor skin, & cushion and insulate deeper tissues
Remembering these characteristics will help you understand the structure and function of the epidermis!

16. Epidermis Strata
The epidermis has multiple strata or layers. Only the deepest layer contains actively dividing cells and melanocytes. Why? Because the deepest layer is closest to the blood supply. As new cells form, older cells are pushed towards the surface

17. Epidermis Strata
As the cells are pushed away from the blood supply, they atrophy and flatten. The most superficial layer is made of the dry, keratinized membranes of skin cells.

18. Epidermis Cells Two main cell types in epidermis: Keratinocytes
Keratin-producing cells
Keratin is the protein that makes skin
tough and waterproof.
Most abundant cell in epidermis
Melanocytes
Melanin-producing cells
Melanin is the brown-black pigment that is largely responsible for skin, hair, and eye color
Melanin absorbs UV light to product DNA from damage
Found only in deepest layer of epidermis
Melanosoma are organelles that synthesis and store melanin

19. Skin Color Major determinants of skin color Adaptive significance
Amount / type melanin
Amount carotene (from fruits and veggies)
Amount oxygen in blood
Adaptive significance
Trade off between UV protection and vitamin D production
Hypodermis is NOT skin. Composed of adipose tissue. Helps anchor skin, & cushion and insulate deeper tissues

20. Dermis The dermis is made of what tissue?
Come, lets gather some berries

21. Dermis
The dermis is made of what tissue? Connective (specifically, dense irregular)
Connective tissue cushions and binds things together. In the skin, the connective tissue holds together lots of different elements:
Exocrine glands
Hair follicles
Nerves and sense receptors
Blood vessels
The collagen and elastic fibers of the dermis give skin its strength and elasticity

22. Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:
Damage extends partway into dermis.
Third degree burn:
Damage extends all the way through dermis.

23. Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:
Damage extends partway into dermis.
Third degree burn:
Damage extends all the way through dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own

24. Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:
Damage extends partway into dermis.
Third degree burn:
Damage extends all the way through dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own
Signs: blistering
Skin will heal with care

25. Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:
Damage extends partway into dermis.
Third degree burn:
Damage extends all the way through dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own
Signs: blistering
Skin will heal with care
Signs: blackened or blanched (gray-white) skin, lack of pain due to damaged nerves
Skin will not heal; grafts must be done

26. How do burns disrupt homeostasis?
Burned skin can no longer carry out its functions
Turn & Talk
Quick review: What are the functions of the skin?
Analyze: Which functions are most critical?
Protection from abrasion / chemical damage / UV damage / pathogens / against dessication
Excretion of wastes
Thermoregulation
Synthesis of Vitamin D

27. How do burns disrupt homeostasis?
Burned skin can no longer carry out its functions
Most critically, skin can no longer
Prevent loss of fluids and electrolytes
Fluid loss and electrolyte imbalance can cause kidneys to shut down and patients to go into shock due to low blood volume.
Happens almost immediately, unless fluids are replaced.
Protect the body from pathogens
Infection becomes a major concern within 2-3 days following severe burns.
(Up to 75% of patients with severe burns die from infection).

28. Other complications of burns
Burned skin cannot thermoregulate.
Hypothermia becomes a problem.
3rd degree burns cannot regenerate.
Scar tissue forms. Scar tissue does a poor job of
perfoming the functions of skin, and if the scar
tissue is extensive, mobility may be affected.

29. Exit Ticket
In a short paragraph explain how burn classification and severity is related to the structure and function of the skin.