1. The Integumentary System
Chapter 6 Pp

2. Objectives 6.1 Skin and Its Tissues 6.2 Accessory Organs
Describe the structure functions of layers of the skin
Summarize factors that determine skin color
6.2 Accessory Organs
Describe the accessory organs associated with skin
6.3 Regulation of Body Temperature
Explain how skin helps regulate body temperature
6.4 Healing of Wounds
Describe the events that are part of wound healing

3. 6.1 Skin and its Tissues
Cutaneous membrane ( the largest organ of the body)
Surface area of 1.2 –2.2 square meters
Weighs 9-11 pounds (7% of total body weight)
Composed of two distinct regions
Epidermis: superficial layer
Dermis: deeper, thicker layer
Beneath the dermis are masses of loose connective tissue and adipose tissue that collectively form the subcutaneous layer or the hypodermis.

4. 6.1 Skin and its Tissues Functions:
First line of defense against outside invaders
Prevents heat and water loss to maintain homeostasis
Houses sensory receptors
Excretes waste
Produces biochemicals (oil and sweat)

5. Beauty is skin deep; ironic.
Composed of keratinized stratified squamous epithelium cells
Outer layer of cells are older cells that have hardened and filled with keratin (a protein)
We lose about 35,000 skin cells every minute
What happens to those lost cells?

6. The Epidermis Replaced every 27 days
Some areas of the skin have five layers (soles and palms) and some have only four.
Stratum Germinativum (Basale): deepest layer; attached to dermis; youngest skin cells; reproductive layer
Stratum Spinosum:Several layers thick; contains melanin (pigment that provides skin color)
Stratum Granulosum: thin, waterproofing layer

7. Stratum Lucidum: clear layer; present in the soles of feet and palms of hands
StratumCorneum: outermost layer; cell fragments; contains keratin to protect skin;glycolipids waterproof this layer

8. Nutrients for the epidermis come from the underlying dermis.

9. Skin Color Biological Factors
Melanin: dark pigment that absorbs UV rays, preventing mutations in the DNA of skin cells; produces yellow to reddish to black coloring
Melanin is produced by melanocytes.
All people have the same amount of melanocytes. It’s the amount of melanin they produce, that determines color.

10. Environmental and Physiological Factors of skin color
Sunlight, UV light from tanning beds, or X-rays increase production of melanin.
The amount of oxygen in blood affects the color of hemoglobin. Excess oxygen leads to pink tone; low amounts lead to cyanosis (bluish tint)
Beta-carotene: yellow to orange tone due to diets high in yellow veggies.

11. The Dermis: the hide Strong, flexible connective tissue
Rich in nerve fibers, blood vessels, and lymphatic vessels; hair follicles, oil and sweat glands
Blood vessels here help regulate body temperature
Stretch marks: stretching of the skin leading to tearing of the dermis

12. Two dermal layers Papillary layer Reticular layer Vascular
Touch receptors called Meissner’s corpuscles
Dermal ridges help increase friction and help create fingerprints
Reticular layer
80% of dermal thickness

13. Hair and fingernails of deceased continue to grow.
Fact or Myth?
Hair and fingernails of deceased continue to grow.

14. A patch of skin approximately 2cm square and 1.5 mm thick has:
2.75 meters of blood vessels
300 eccrine glands
30 hairs
600 pain receptors
4 sebaceous glands
9000 nerve endings
6 cold sensors, 36 heat sensors, 75 pressure sensors
And almost 12 meters of nerves!

15. 6.2 Accessory Organs Nails Sebacceous glands Hair Follicles
Protective covers on the ends of fingers and toes
Specialized keratinized cells
Hair Follicles
Hair develops from epidermal cells originating at the base of a follicle
Newly formed cells push older cells outward to be keratinized
Hair color is determined by genes that control amount of melanin produced
Grows an average of 9 inches/yr
Sebacceous glands
Usually associated with hair follicles
Secrete sebum, a waterproofing oil
Sweat Glands
A coiled tube
Sweat is primarily water but also contains waste and salt
Two types: apocrine and eccrine

16. Try this at home!
Clean one palm of your hand with a cotton ball soaked in rubbing alcohol. Use the other palm as your control. Run water over both your palms, shake off access water, and observe. You will probably notice that the water soaks in more on the palm that you cleaned with alcohol. What is the purpose of the rubbing alcohol in the experiment?

17. Sudoriferous Glands (Sweat glands):
Apocrine gland: become active at puberty; respond to emotions and are located in the axillary and groin regions
Eccrine gland: respond throughout life in response to temperature; associated with forehead, neck, and back

18. 6.3 Regulation of Body Temperature
The skin plays a key role in the homeostatic mechanism that regulates body temperature. Normal body temperature is 98.6F.
Body temp. increases:
dermal blood vessels relax and swell,
sweat glands produce sweat
Body temp. decreases:
Dermal blood vessels contract pushing blood toward vital organs
Muscles in skin contract to produce friction

19. 6.4 Healing of wounds Inflammation
Redness, heat, swelling, pain
Scabs are formed when injury extends into the dermis and escaping blood forms a clot.
Granulations are small, rounded masses in exposed tissues of large wounds. These lead to scar formation.

20. Venous breakdown
                                                                                      

21. Pressure Sore
                                                               

22. Burns