1. The Integumentary System

2. Major roles of the Integumentary System
protection
maintenance of normal body temperature
storage (of fat)
synthesis (of vitamin D)
excretion (of salts, water and wastes in sweat)
sensory perception

3. The Skin: 3 Major layers

4. Did You Know?...
At 8-10 pounds, the skin is bodies largest organ!

5. The Epidermis
The epidermis is the outer layer of skin. The thickness of the epidermis varies in different types of skin. It is the thinnest on the ______ at .05 mm and the thickest on ______ at 1.5 mm.
Cells of the epidermis are constantly sloughing off and replacing themselves…

6. The Epidermis cont… 5 layers
Cells are shaped like columns at the base and migrate upward, as dead cells are continuously sloughed off at the surface
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale

7. Epidermal Layers stratum corneum
the outermost layer of the epidermis is composed of large, flat, plate-like cells filled with keratin, these dead cells have migrated up from the stratum granulosum
stratum lucidum
This thin layer is made up of 3 to 5 layers of dead, flattened keratinocytes. Here, melanocytes determine the darkness of the stratum lucidum. Thickness of the lucidum is controlled by the rate of mitosis in the cells below.
stratum granulosum
In this, the granular layer, cells have lost their nuclei and are characterized by dark clumps of cytoplasmic material. There significant activity here, as keratin proteins and water-proofing lipids are being constructed/organized.

8. Epidermal Layers stratum spinosum
Cells that move into the spinosum layer (referred to as the prickle cell layer) change from being columnar to polygonal. In this layer the cells start to synthesize keratin.
stratum basale
The bottom layer the epidermis responsible for constantly renewing epidermal cells. This layer contains a single row of columnar stem cells that divide very frequently. About Half of the cells begin to flatten and move to the next layer in the maturation process. The other half remain in the basal layer and divide over and over.

10. Which layer of the epidermis is this?

11. Specialized Epidermal Cells
The melanocyte- produces pigment (melanin)
The Langerhans' cell- frontline defense of the immune system in the skin
Merkle Cells are highly sensitive ‘light’ touch receptors (neurons) found in the basal layers of the epidermis

13. The Dermis
This layer varies in thickness as well, depending on the area of the body. It is a mere 0.3 mm on the eyelid and 3.0 mm on your back.
The dermis is composed of 3 types of tissue….

14. The Dermis cont…
2 types of tissue that are present throughout (not in layers).
collagen
elastic Areolar (loose) connective tissue

15. Dermis: Elastic tissue
Elastic protein fibers made by cells called fibroblasts provide protection for tissues underneath the dermis as well as the pliability we associate with the skin.
Areolar connective tissue providing a support infrastructure for blood vessels, nervous tissue and specialized dermal structures. It also acts as a reservoir for glucose, essential ions, and water.

16. Dermis Tissue: Collagen
Collagen is the most abundant and important structural protein in your body. It strengthens and supports many body tissues from the outside creating an “extracellular matrix.”

17. Specialized Dermal Cells
arrector pili muscle cells support hair follicles.
oil (sebaceous) glands, scent glands, and sweat glands are associated with the follicle.
Blood vessels and nerves course through this layer. The nerves transmit sensations of pain, pressure, itch, and temperature, and blood vessels facilitate gas exchange.

18. Glands Galore! Sebaceous glands
Sebaceous glands are located near the hair follicle and produce sebum - the natural oil of your skin.
Sebum is a mixture of different waxes and fats, and the facial skin contains nearly three thousand of these glands per square inch.

19. Glands (cont.) Apocrine glands Eccrine glands
In the armpit, belly button, genital and anal areas of the body
situated deep within the dermis and produce a milky type of sweat, causing body odor when bacteria breaks it down on the epidermis.
In animals these glands produce body odors that attract sexual partners. Some believe the same holds true for humans….
Eccrine glands
Unlike sebaceous and apocrine glands, they do not use the hair follicle to exit sweat to the skin, each has its own dedicated pore.
Sweat glands regulate body temperature, as draws heat away from the body.
Eccrine sweat is also helpful in eliminating waste salts from the body.

21. 1 Square inch if Skin Contains…

23. What makes these hairs stand on end? Why?

24. Can you name structures 1-4?

25. Layer 3: The Subcutaneous
Also referred to as the “hypodermis,” this layer of the skin is composed primarily of adipose tissue (fat). This layer plays a key role in insulating the body and regulating the temperature of the skin.
The hypodermis can vary significantly in thickness and incorporates larger blood vessels and nerves.

27. Nails
Your nails extend from the epidermis and contain a tough protein called keratin. They play an important role in grasping objects, scratching, and protecting fingers and toes.

29. A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G
A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G. hyponychium; H. free margin

30. Did you Know?
Your fingernails grow about 5 times faster than your toenails!

31. Hair
Also composed of the protein keratin hair acts as an effective insulator between you and the environment.
hair follicles originate in the dermis.

35. Did you know?
Humans have more hair than apes. Although theirs is thicker, longer, and typically darker.

36. Challenge Question!
The hair in your ears, nose, and around your eyes play important roles in keeping you healthy….Can you explain why?

37. Did You Know?
Hair can grow as little as 0.1 inches per month or as fast as 0.5 inches per month depending on genetics and your diet.

38. Damaging the Skin
Puncture wounds are caused by a sharp object that penetrates the skin. Such wounds may cause significant deep injury that is not immediately recognized. These types of wounds do not bleed freely
The most common type of open wound is a laceration. Lacerations are commonly called cuts and are an irregular cut or tear through the skin.
Abrasions are commonly called scrapes. They occur when the skin is rubbed across a rough surface. Abrasions involve variable depths of skin.
An avulsion is a tearing away of body tissue. Avulsions raise flaps of tissue, usually along normal tissue planes. The avulsed part may be totally severed from the body or it may be attached by a flap of skin.

39. Aging and the integumentary system
Marked declines in:
Cell division in stratum basale
Melanocyte production
Glandular activity
Hair follicle function
Elastic fiber function in dermis
Blood supply to skin
Rate of repair

40. Disorders of the skin Lesions and tumors
infections (bacterial, viral, fungal, parasitic)
inflammatory reactions and allergies
Genetic diseases
acne

41. Anatomy of a Pimple