1. NOTES: Accessory Organs of the Skin

2. ACCESSORY ORGANS OF THE SKIN:
 HAIR & HAIR FOLLICLES
• function: protection (eyebrows/eyelashes/scalp)
• each hair (pili) develops from epidermal cells at the base of a tube-like hair follicle
                            

3. -shaft: dead, keratinized cells that project above scalp
• Anatomy: shaft & root
-shaft: dead, keratinized cells that project above scalp
-root: below surface; penetrates into dermis/subcutaneous layer

4. • as new cells develop and grow, older cells are pushed toward the surface and undergo KERATINIZATION
• a bundle of smooth muscle cells is attached to each hair follicle (ARRECTOR PILI MUSCLE)

5.  HAIR FOLLICLES
• hair color is determined by GENES that direct the amount of MELANIN produced by the melanocytes associated with the hair follicles
• hair thinning during mid-life results from the atrophy of hair follicles; hairs are not replaced as fast as they are lost
• male-pattern baldness
is likely caused by more
than 1 gene &
environmental factors

8. Alopecia: baldness due to attack by your own immune system on hair follicles; a permanent loss of hair on the scalp 8

9. ACCESSORY ORGANS OF THE SKIN:
 SEBACEOUS GLANDS (oil glands)
• usually associated with hair follicles
• secrete SEBUM (oily substance) – helps keep skin and hair soft and waterproof

10. ACCESSORY ORGANS OF THE SKIN:
 SWEAT GLANDS
• each sweat gland is a COILED TUBE
• sweat is mostly water (plus some salts and waste products)

11.  SWEAT GLANDS (aka: Sudoriferous Glands)
• ECCRINE sweat glands respond to elevated body temperature
- Common on forehead, neck and back
• APOCRINE sweat glands respond to emotional stress
Most numerous in axillary region and groin

13. ACCESSORY ORGANS OF THE SKIN:
 CERUMINOUS GLANDS
• modified apocrine glands found in the lining of the external ear canal
• secrete earwax which is thought to deter insects & block foreign material from entering
                                

14. ACCESSORY ORGANS OF THE SKIN:
 MAMMARY GLANDS
• specialized apocrine glands that secrete milk

15. ACCESSORY ORGANS OF THE SKIN:
 NAILS
• protective covers on ends of fingers and toes
• formed by specialized epidermal cells that are keratinized
• keratin in nails is harder than that produced by epidermal cells in skin

16. REGULATION OF BODY TEMPERATURE
*Regulation of body temp. is vital because heat affects the rates of metabolic reactions. The normal temperature is close to a “set point” of 37ºC (98.6ºF). This is regulated by a part of the brain called the HYPOTHALAMUS.

17. REGULATION OF BODY TEMPERATURE
When body temperature…
RISES: dermal blood vessels dilate (we look “flushed”) and eccrine sweat glands secrete sweat (evaporative cooling)
 DROPS: dermal blood vessels constrict (we look pale) and eccrine sweat glands become inactive

18. REGULATION OF BODY TEMPERATURE
*excessive heat loss stimulates skeletal muscles to contract involuntarily (hair stands up; “goosebumps”)
**FEVER is the result of the hypothalamus raising the body’s temperature “set point” as part of your immune system response

19. HEALING OF WOUNDS:
*Skin injuries trigger INFLAMMATION. The affected area becomes red, warm, swollen, and tender.

20. HEALING OF WOUNDS: SHALLOW CUTS:
• dividing epithelial cells fill in shallow cuts in the epidermis
• white blood cells phagocytize microbes

21. -epithelial cells migrate beneath scab to bridge wound
DEEP CUTS: (epidermis & dermis)
• After inflammation & blood clotting to unite the wounded edges, the clot becomes a scab
-epithelial cells migrate beneath scab to bridge wound
-fibroblasts migrate & begin synthesizing scar tissue (collagen & glycoproteins)
-blood vessels regrow
•after extensive epithelial cell division, the scab sloughs off and the epidermis is restored

23. Bottom has specially formulated silicone (called Silon)
-research suggests that it hydrates the scar which helps break down excess collagen

24. OTHER SKIN TRAUMA: blisters
A blister is a partial separation of the epidermis from the dermis. The space is filled with lymphatic fluid to protect the damaged skin.

25. COMMON SKIN DISORDERS:
• ACNE: disorder of the sebaceous glands; pores become clogged by overproduction of oil
Traps dirt and bacteria
produces blackheads,
whiteheads, pimples
• DANDRUFF: caused by accumulated oil and skin cells

26. COMMON SKIN DISORDERS:
• RING WORM: contagious fungal infection
direct skin-to-skin contact with an infected person or pet
2) indirect contact with an object or surface that an infected person or pet has touched
 Ringworm can be treated with fungus-killing
medicine.
•ATHLETE’S FOOT: same fungus as ringworm; usually affects skin of the toes and soles
Causes scaling, flaking, and itching of the affected skin. Blisters and cracked skin may also occur

27. COMMON SKIN DISORDERS:
• IMPETIGO: bacterial infection; pustules rupture and become covered with crust
Associated with streptococcus and staphylococcus bacteria (ex. MRSA)
More common in children
• ECZEMA: noncontagious skin rash that produces itching, blistering, and scaling (unknown cause; genetics? allergy?)
- treat with oatmeal lotions to keep hydrated

28. ECZEMA

29. COMMON SKIN DISORDERS:
• PSORIASIS: red patches covered with scales (excess skin cell growth)
-Psoriasis is thought to be an autoimmune disorder

30. COMMON SKIN DISORDERS:
• PEDICULOSIS: lice infestation
• MOLES: fleshy skin tumors; usually pigmented (brown to black)

31. MOLE CHECK!
ABCDEs of moles: If a mole displays any of the signs listed below, have it checked immediately by a dermatologist.
Asymmetry: One half of the mole does not match the other half.
Border: The border or edges of the mole are ragged, blurred, or irregular.
Color: The color of the mole is not the same throughout or has shades of tan, brown, black, blue, white, or red.
Diameter: The diameter of a mole is larger than the eraser of a pencil.
Evolution: The mole is changing in size, shape, or color. 

32. COMMON SKIN DISORDERS:
•WARTS: raised area caused by an HPV virus

33. • SHINGLES: Shingles (herpes zoster) is a painful, blistering skin rash due to the varicella-zoster virus, the virus that causes chickenpox.
After you get chickenpox, the virus remains becomes dormant in certain nerves in the body. Shingles occurs after the virus becomes active again in these nerves years later.
Shingles may develop in any age group, but you are more likely to develop the condition if you are older than 60, had chickenpox before age 1, or are immune compromised

34. Skin Color Conditions:
Albinism- have regular amounts of melanocytes but lacks the enzyme which converts the amino acid tyrosine to melanin
Autosomal recessive disorder
Jaundice- yellowish
color due to excess of
bile pigment in
bloodstream (liver
dysfunction/immaturity)

36. Cyanosis- bluish discoloration that appears as a result of cardiovascular or respiratory diseases; interruption of breathing
*Hemoglobin: NOT a skin pigment but binds oxygen in red blood cells; oxygenated blood flowing through dermis gives skin pinkish tones

37. Already in notes elsewhere:
Alopecia: autoimmune caused hair loss
Blisters: separation of epidermis from dermis