Hair

1
Accessory Organs of the Skin

1. Hair
2. Skin glands
3. Nails

2
1. Hair

• Forms from epidermal cells
• Housed in the hair follicle
• 2 distinct sections
• Shaft portion that projects from skin surface
• Root deep portion penetrating the dermis
• Arrector pili muscles
• Smooth muscle attached to each hair follicle
• Contract when stimulated by cold or nervous
  impulses, pulling hair up straight and causing
  goosebumps
• Hair root plexus dendrites of neurons that are
  sensitive to touch

3
2. Skin Glands

• Sebaceous glands
• seb grease
• Oil-producing (Why do we want this?)
• Usually associated with hair follicles in the
  dermis
• Keep hair and skin soft, pliable, and waterproof
• Sudoriferous glands
• sudori sweat ferous bearing
• 2 main types
• Eccrine secretes cooling sweat directly onto
  the skin
• Apocrine stimulated during stress/excitement
  secreted into hair follicles
• Modified sweat glands
• Ceruminous (cer wax) external ear canal
• Mammary - milk-producing

4
3. Nails

• Made of tightly packed, keratinized (???)
  epidermal cells
• Consists of
• Nail body visible portion
• Free edge part that extends past the end of the
  digit
• Nail root portion buried in a fold of skin
• Lunula (little moon) crescent-shaped area of
  the nail

5
Functions of Integument

• Protective covering
• Prevents water loss
• Keeps microbes and contaminants out
• Cutaneous sensation gathers information of
  environment
• Excretion and absorption
• Synthesis of vitamin D
• Wound healing
• Temperature regulation

6
Temperature Regulation

• When body temperature is too high
• Blood vessels in the dermal area dilate, so heat
  can be released to the environment.
• Sweat glands are stimulated, and the evaporating
  sweat cools the body.
• What happens when the body is too cold?