1. Integumentary System
FUNCTIONS & CELL TYPES

2. Cells in the epidermis:
- keratinocytes
- melanocytes
- Langerhans cells
- Merkel cells

3. 1)
KERATINOCYTES
- produce protein keratin
- protective; waterproofing the skin
- mitosis in stratum basale
- regenerates every days

4. Epidermis: keratinized stratified squamous epithelium with four distinct cell types and five distinct layers.

7. 2) MELANOCYTES
- cells produce brownish/black pigment
called melanin in stratum basale

8. 3) LANGERHANS CELLS
- cells arising from bone marrow that migrate to epidermis (mostly stratum spinosum)
- they are epidermal macrophages
- interact with white blood cells
- easily damaged by UV light

9. 4) MERKEL CELLS
- in stratum basale
- make contact with a sensory neuron ending called a Merkel disc (for sense of touch).

10. Cells in the dermis: Meissner corpuscles Thermoreceptors
Mechanoreceptors
Nociceptors
Pacinian corpuscles

11. MEISSNER CORPUSCLES
- Receptors for fine touch

12. THERMORECEPTORS
- Detect changes in temperature

13. MECHANORECEPTORS
Detect pressure/mechanical stimuli
or stretching

14. NOCICEPTORS
- Detect pain

15. PACINIAN CORPUSCLE
- Receptors that detect pressure

16. PHYSIOLOGY – FUNCTIONS OF SKIN
1) Regulation of BODY TEMPERATURE
vasodilation (increases blood flow) and vasoconstriction (decrease in blood flow) regulates body temp. and through evaporation of sweat
Sudoriferous glands & blood vessels

17. 2) PROTECTION
physical barrier that protects underlying tissues
Protection includes immune functions of cells
Keratinocytes

18. 3) SENSATION
nerve endings and receptor cells that detect stimuli to temperature, pain, pressure and touch.
Merkel cells, Thermoreceptors, Nociceptors, Mechanoreceptors, etc.

19. 4) EXCRETION
sweat removes water and small amounts of salt, uric acid and ammonia from the body surface
Sudoriferous glands

20. 5) IMMUNITY
cells of the epidermis fight off foreign invaders
Langerhans cells, macrophages

21. 6) SYNTHESIS of Vitamin D
UV rays in sunlight stimulate the production of Vitamin D.
Melanocytes