lecture 5 integumentary system Flashcards
-largest organ
-accounts for 7% body weight
-varies in thickness
-divided into 2 layers ;
epidermis & dermis
skin
- lies deep to the dermis
- also called superficial fascia
- composed of areolar and adipose tissue
- not part of the integumentary systems, but shares skins properties
- helps insulate the body
- different distribution in males and females
hypodermis
five important functions of skin
- protection
- body temperature regulation
- excretion
- production of vitamin D
- Sensory reception
cushions organs and protects from bumps, chemicals, water loss, UV radiation
protection
capillary network and sweat glands regulate heat loss
body temperature regulation
urea, salts, and water lost through sweat
excretion
epidermal cells use UV radiation to synthesize vitamin D
production of vitamin D
contains sense organs associated with nerve endings
sensory reception
4 layers of epidermis
- stratum basale
- stratum spinous
- stratum lucid
- stratum corneum
- deepest layer of epidermis
- attached to underlying dermis
- cells actively divide
- contains tactile epithelial cells and melanocytes
stratum basale
associated with sensory nerve ending
tactile epithelial cells
secrete the pigment melanin
melanocytes
- occurs only in thick skin
- location of thick skin ; palms and soles
- composed of a few rows of flat, dead keratinocytes
stratum lucidum
- second major region of the skin
- strong, flexible connective tissue
- richly supplied with blood vessels and nerves
- 2 layers ; papillary and reticular dermis
dermis
- includes dermal papillae
- increase surface area for exchange of gases, nutrients, and wastes
- dermal papillae on dermal ridges
papillary dermis
- elevations of dermal ridges
- fingerprints
- increase gripping ability of hands and feet
epidermal ridges
- accounts for 80% of dermal thickness
- dense irregular connective tissue
- cleavage lines
- collagen fibers give skin strength
- flexure lines
- rich nerve supply
- 2 vascular plexuses ; dermal and sub papillary plexus
- blood vessels play important role in temperature regulation
reticular dermis
separation between collagen fibers
-collagen fibers give skin strength
cleavage lines
deep crease in palms, wrists, soles, fingers, and toes
flexure lines
