Unit 2 - A&P

• skin
• hair
• nails
• glands

• protection
• sensation
• temperature regulation
• vitamin D production
• excretion
• immunity

provides physical, chemical, and pathological barriers from impact, chemicals, infections, pathogens, UV light

detects tactile touch, temperature, pressure, pain, vibrations, and tickling

regulates heat loss or gain, changes blood vessel diameter, allows us to sweat

when exposed to UV light, the skin produces an inactive form of vitamin D (cholecalciferol), when activated by the kidneys/liver (calcitriol) it aids in the absorption of calcium and phosphorous from the GI tract

excretes water, salts, organic wastes; innate immune protection against foreign invaders, macrophages

• has stratified squamous keratinized epithelia
• protects against UV lights by melanin production
• lipids in epidermis reduce water loss

the epidermis

the dermis

• not part of the skin
• loose connective tissue that connects skin to underlying tissue

• layers
• strata

basement membrane

• avascular
• papillary

most cells, produce keratin for strength

• contribute to skin colour
• melanin produced by these cells then transfer to keratinocytes
• *same number of melanocytes in everyone

part of the immune system

detect light, touch, and superficial pressure

cells of the deeper layers undergo mitosis; as they move toward the surface, older cells slough off

Frontal Bone

False. The canaliculi are small canals that were formed by the thin processes arising from the young osteoblasts.

False. Collagen protein fibers allow a bone to have a degree of flexibility; the calcium salts provide a rigidity.

Cutaneous

• True. Keratin synthesis is a function of the stratified squamous cells of the
• epidermis and does make the layer relatively impermeable to water.

• False. Decubitus ulcers are areas of dying skin tissue which result from the
• lack of an adequate blood supply, usually caused by pressure; it is
• possible to also be infected secondarily.

• epidermis
• dermis

adipose

blood vessels