Chapter 5 Flashcards
integument
skin
what is the largest organ
skin
how large and thick is the skin
22 sq fit, 10-11 lbs, and 0.5-0.6 mm
what are the two layers of the skin
epidermis
dermis
what is the epidermis
- superficial layer (epithelium of the skin)
- stratified squamous epithelium
- avascular
- keratinized stratified squamous epithelium
- composed of several layers
what are layers of the epidermis called
strata
what is the dermis
depper layer of areolar and dense irregular connective tissue
hypodermis
subcutaneous layer
not a part of the skin, but lies under the dermis and is composed of mostly adipose tissue
functions of the integument
- Protection
- Prevention of water loss
- Temperature regulation
- metabolic regulation
- immue defense
- sensory reception
- excretion by means of secretion
epidermal strata
- stratum basale
- stratum spinosum
- stratum granulosum
stratum lucidum (found only in thick skin) - stratum corneum
what is the deepest strata called
stratum basale
what is the most superficial layer of state called
stratum corneum
stratum basale
- single layer of cells that are capable of mitosis
- the cells that are adjacent to the dermis
where do the multiplied cells go
they are pushed up and lose the ability to reproduce
what are the cells in the stratum basale
- keratinocytes
- melanocytes
- tactile cells
keratinocytes
- most abundant
- produce keratin to protect and waterproof the skin
melanocytes
- cells that produce the pigment melanin
- which absorbs UV light to prevent DNA damage
tactile cells
cells sensitive to touch
stratum spinosum
- several layers thick of the reproduced cells from the stratum basale
- differentiated into nondividing, highly specialized keratinocytes
what are the cells present in the stratum spinosum
epidermal dendritic cells
epidermal dendritic cells
- immune cells that help fight infection
- phagocytes that initiate an immune response
stratum granulosum
- 3-5 layers thick of keratinocytes
- the cytoplasm fills with keratin filaments
- organelles begin to degrade
- fully keratinized cells are dead but strong
- extracellular lipids form epidermal water barrier
stratum lucidum
- think, translucent region
- 2-3 layers thick
- present only in thick skin (palms, soles of the feet, places with no hair)
descirbe the cells of the stratum lucidum
- lack organelles
- filled with eleidin: transparent, intermediate product of keratin maturation
stratum corneum
- most superficial layer of the epidermis
- thickness varies from 20-30 layers depending on person and their activities
- comprised solely of dead keratinocytes
keratinization
cells formed on basal accumulate keratin as they are pushed up
how long does keratinization take
about 5 weeks for a cell to be formed
what does repeated abrasion do to the cells
will cause abnormal development and a thick stratum corneum to form
