LESSON 5: INTEGUMENTARY SYSTEM Flashcards
largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain.
integumentary system
components of integumentary system
skin
nails
hair
cutaneous sense organs and glands
2 major tissue layers of the skin
epidermis and dermis
- superficial layer
- stratified squamous epithelium
- cornified or keratinized (hardened by keratin) to prevent water loss
- avascular
- most cells are keratinocytes
epidermis
prevents water loss and resists abrasion
epidermis
- dense connective tissue
- vascular
- 10-20 times thicker than the epidermis
- layer of dense connective tissue depending on location
(blood vessels, oil and sweat glands, nerves, hair follicles, and other structures)
dermis
- responsible for most of the skin’s structural strength
- skin rests on the subcutaneous tissue, which is a layer of connective tissue
(ex. areolar, adipose) - not part of the skin, but it connects skin to underlying muscle or bone
dermis
- functions as padding and insulation
- acceptable percentage of body fat varies from 21% to 30% for females and 13-25% for males
dermis
- cells are dead
- represented only by flat membranous sacs filled with keratin
- glycolipids in extracellular space
stratum corneum
- cells are flattened
- organelles are deteriorating
- cytoplasm full of granules
stratum granulosum
- cells contain thick bundles of intermediate filaments made of pre-keratin
stratum spinosum
- cells are actively dividing stem cells
- some newly formed cells become part of the more superficial layers
stratum basale
dermis consists of
sensory nerve ending
melanin granules
melanocytes
excessive sloughing of stratum corneum cells from the surface of the scalp is called
dandruff
in skin subjected to friction, the number of layers in the stratum corneum greatly increases, producing a thickened area called
callus
keratinization is also called
cornification
keratinocytes proliferate in the
basal layer (mitosis)
a complex process that results in the production of the impermeable stratum corneum
terminal differentiation (keratinization)
LAYERS OF THE EPIDERMIS
thick hairless layer
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale
dermis
- deepest layer of epidermis
- lies next to dermis
- wavy borderline with the dermis anchors the two together
stratum basale (stratum germinativum)
- cells undergoing mitosis
- daughter cells are pushed upward to become the more superficial layers
stratum basale (stratum germinativum)
- several layers thick
- contain a weblike system of intermediate filaments
stratum spinosum (pricky layer)
- 4-6 layers thick
- accumulates two types of granules: KERATOHYALINE GRANULES and LAMELLAR GRANULES
stratum granulosum (granular layer)
help to form keratin in the upper layer
keratohyaline granules