1. Skin and the Integumentary System
Chapter 6

2. Skin is… is the largest & heaviest organ in the body. covered in hair.
vital in maintaining homeostasis.
a protective barrier.
a.k.a. the cutaneous membrane.

3. Skin is… part of the integumentary system.
divided into three distinct layers:
EPIDERMIS – outer layer
DERMIS – middle layer
SUBCUTANEOUS – bottom layer
(Not a true skin layer )

4. EPIDERMIS Stratified squamous epithelium Old cells die are pushed up
Cytoplasm hardens, fills with keratin
KERITINIZATION
Forms tough, waterproof layer
- STRATUM CORNEUM

5. EPIDERMAL LAYERS Stratum corneum Stratum lucidum Stratum granulosum
Only in thick skin
Stratum granulosum
Stratum spinosum
Stratum basale

6. MICROSCOPIC EPIDERMIS

7. EPIDERMAL PROTECTION Stratum basale contains MELANOCYTES
Produce MELANIN
Dark pigment in granules that absorbs UV radiation
Granules spread to nearby cells

8. SKIN COLOR Everyone has the same # of melanocytes Other factors:
Light Skin
Everyone has the same # of melanocytes
Skin color depends on amount of melanin produced
Other factors:
Blood supply
Beta – carotene
Bilirubin
Dark Skin

9. THE KING OF POP What’s up with M.J.’s skin?
Vitiligo – disorder in which the skin’s melanocytes are destroyed

10. VITLIGO Possible causes:
Body is allergic to its own melanocytes
Cells destroy themselves during pigment creation
FYI – Cancer patients can develop vitiligo after treatment; the weird thing?
The vitiligo actually seems to stop the spread of the disease!

11. BACK TO M.J. Underwent repigmentation Process failed
Turn white patches dark again.
Process failed
Went through depigmentation to reverse it
Monobenzene is used to bleach the skin until it’s all the same color
If he stopped the treatments, he would turn back

12. ALBINISM
Body is unable to produce or distribute melanin due to possible genetic defects
High risk of skin cancer and eye problems

13. PSORIASIS
Excessive growth and reproduction of keratinocytes followed by inflammation
Caused by the immune system mistakenly reacting
Speeds up creation of new cells and slows loss

14. WHAT ARE THOSE WHITE SPOTS ON MY FINGERNAILS?
Leukonychia
Can be caused by trauma
Not a calcium deficiency
Zinc deficiency is more pronounced

15. HOW THICK IS YOUR SKIN? Epidermis: Dermis: .5 mm on eyelids
Up to 1.5 mm on palms/soles
Dermis:
.3mm on eyelids
3 mm on upper back

16. DERMIS Directly below epidermis
Dermal papillae project upwards into epidermis
Produce fingerprints
Made mostly of dense connective tissue

17. DERMAL STRUCTURES

18. BEDSORES
Interference with blood flow to the dermis can kill epidermal cells
Lying in one position too long causes weight of body to block skin’s blood supply
A.k.a. PRESSURE ULCER
Treatment includes shifting the patient frequently and keeping the wound clean

19. SUBCUTANEOUS LAYER A.k.a. HYPODERMIS
Loose connective and adipose tissue
Insulation
Major blood supply

20. SEVERITY OF BURNS

21. INJECTIONS SUBCUTANEOUS INJECTION INTRADERMAL INTRAMUSCULAR
Flu shot, penicillin
INTRADERMAL
TB test
INTRAMUSCULAR
Epinephrine injection

22. ACCESSORY ORGANS OF THE SKIN
NAILS
HAIR FOLLICLES
SEBACEOUS GLANDS
SUDORIFEROUS GLANDS

23. NAILS Protective coverings
NAIL ROOT & LUNULA contain actively dividing cells
Cells die and become keratinized forming nail body

24. HAIR FOLLICLES Hair development Specialized epidermal tissue
Nourished by dermal blood supply
Cells divide near base and become keratinized

25. HAIR FOLLICLES Hair color is determined by melanocytes near root
More melanin produced, darker hair
ARRECTOR PILI- smooth muscles that control “goose bumps”

26. SEBACEOUS GLAND Specialized epithelial gland that produces SEBUM
Oily mixture that keeps hair and skin soft, pliable and waterproof
Attached to follicles

27. SUDORIFEROUS (SWEAT) GLANDS
Tiny tube that is attached to a coil in dermis
ECCRINE GLANDS respond to temperature
Sweat comes out of PORE
Forehead, neck, back

28. SUDOIFEROUS (SWEAT) GLANDS
APOCRINE GLANDS
Respond to emotions
Active at puberty
Groin, axillary regions

29. SKIN SENSORY RECEPTORS
The skin has receptors for “touch”
Heat
Pressure
Pain
Cold

30. SKIN TOUCH RECEPTORS MERKEL’S DISCS ROOT HAIR PLEXUS
Sensitive to vibration & movement
Found in stratum basale
ROOT HAIR PLEXUS
Sensitive to hair movement

31. SKIN PRESSURE RECEPTORS
MEISSNER’S CORPUSCLES
Light touch – objects that brush the skin
Dermis
PACINIAN CORPUSCLES
Heavy pressure
Dermis/Subcutaneous layer

32. OTHER SKIN RECEPTORS THERMORECEPTORS Cold Heat PAIN RECEPTORS
KRAUSE CORPUSCLES
Cold
RUFFINI CORPUSCLES
Heat
PAIN RECEPTORS
Free nerve endings

33. Hyperhidrosis Overactive sweat glands
Hands
Feet
Armpits
Caused by overactive nervous system
Treatment:
Antiperspirant
Iontophoresis
Botox injections

34. The Skin’s Role in Homeostasis
Vital in maintaining proper body temperature
Important in the healing of wounds
Aids in production of Vitamin D

35. VITAMIN D PRODUCTION Skin cells help produce vitamin D
Dehydrocholesterol made by cells in digestive system
Reaches skin and is changed to vitamin D when exposed to UV light

36. Regulation of Body Temp
During intense heat, nerve impulses signals the body to release heat
Blood vessels dilate, giving off heat through skin
Eccrine sweat glands become active
Sweat evaporates cooling skin

37. Regulation of Body Temp
If too much heat is lost:
Muscles in dermal wall contract
Decreases blood flow and heat loss
Sweat glands inactive
Skeletal muscles contract involuntarily
Release heat
“Shivering”

38. Healing of Wounds
INFLAMMATION – wound and surrounding areas become swelled
Response to injury & stress
4 signs of inflammation:
Redness
Warmth
Swelling
Pain

39. Inflammation Redness - caused by increased vasodilatation
More blood in area
Heat – increased metabolism; WBC’s try to destroy invaders

40. Inflammation
Swelling – Fluid in area due to change in osmotic pressure
Abnormal build up of fluid called EDEMA
Pain –Pressure on nerve endings from fluid

41. Healing of Wounds Shallow wounds (epidermis)
Epithelial cells divide and fill in gap

42. Healing of Wounds Deep wounds (dermis or subcutaneous layer)
Blood vessels broken
Clot forms and dries into a scab
Fibroblasts lay down collagen fibers forming scar
Phagocytes remove foreign particles