Transcript Accessory Organs of the Skin

Accessory Organs of the Skin
1. Hair
2. Skin glands
3. Nails
1. Hair
A. Forms from epidermal cells
B. Housed in the hair follicle
C. 2 distinct sections
1) Shaft – portion that projects from skin surface
2) Root – deep portion penetrating the dermis
D. Arrector pili muscles
1) Smooth muscle attached to each hair follicle
2) Contract when stimulated by cold or nervous impulses,
pulling hair up straight and causing goosebumps
E. Hair root plexus – dendrites of neurons that are sensitive to
touch
2. Skin Glands
A. Sebaceous glands
1)
2)
3)
4)
“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
B. Sudoriferous glands
1) “sudori ” = sweat; “ferous ” = bearing
2) 2 main types
a) Eccrine – secretes cooling sweat directly onto the skin
b) Apocrine – stimulated during stress/excitement; secreted into
hair follicles
3) Modified sweat glands
a) Ceruminous (“cer ” = wax) – external ear canal
b) Mammary –- milk-producing
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
Functions of Integument
1. Protective covering
– Prevents water loss
– Keeps microbes and contaminants out
2. Cutaneous sensation – gathers information of
environment
3.
4.
5.
6.
Excretion and absorption
Synthesis of vitamin D
Wound healing
Temperature regulation
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?