• protection against abrasion & bacteria
• thermal regulation (sweat)
• secretion of oils: skin is waterproof
• storage of fat
• production & storage of Vit D
• sensory: touch, temp, pressure, pain

• stratified squamous keratinized epithelium
• four cell types
• nerves, ducts of glands, NO blood vessels

• loose & dense irregular CT
• glands,bloos vessels, nervs, hair follicles, smooth muscle

• not part of skin
• superficial fascia, subcutaneous tissue
• loose CT, fat

• most of body
• thinner epidermis
• hari follicles w/sebaceous glands
• arrectot pilli muscle
• eccrine sweat glands
• apocrine sweat glands

• palms & soles
• thicker epidermis
• no hair follicles, arrector pilli muscle, or sebaceous gland
• eccrine glands
• no apocrine glands

Keratinocytes

• most numerous epithelial cell of the epidermis, and are arranged in 5 layers
  • stratum corneum
  • stratum lucidum
  • stratum granulosm
  • stratum spinosum
  • stratum basale

• single layer of keratinocytes resting on the basal lamina
• attached to the basal lamina w/hemidesmosomes
• mitotic cells of the epidermis
• the source of cells to regenerate the epidermis

• essentially dead keratinocytes filled with keratin
• nuclei & organelles are degraded
• this layer is shed from the surface of the epidermis

• produce melanin pigment for skin coloration & production against UV radiation

• upon infection of an area of skin, the local Langerhans cells will take up & process microbil antigens

• associated w/nerve ending
• believed to function as touch receptors or mechanoreceptors

• said to be dense irregular

Eccrine Sweat glands

• sweat produced by secretory cells & released on to the surface of the skin by single duct
• sweat controls body temp
• induced by thermal stimulu & by emotional stress

• glands in armpit
• secretory cells secrete a mucin that empties on to the surface of the skin though a duct associated w/hair follicle
• bacteria metabolize the mucin & create an order
• function not clear

• secretory cells secrete sebum that goes through a hair follicle out on the surface of skin
• sebum moisturizes hair and skin

• free nerve endings w/in epidermis are nociceptors
• merkel cell is assocaited w/a sensory nerve to function as a mechanoreceptor
• meissner's corpuscles are mechanoreceptors
  • distributed throughout the skin, but concentrated in areas especially sensitiveto light touch, such as finger types
• paccinian corpuscles function as mechanoreseptors