Integument Flashcards
what is the integument?
the largest organ in the body that generally functions as a protective barrier against injury
what is the integument composed of?
skin and skin appendages
what are the skin appendages?
- nails
- hair
- sweat glands
- sebaceous glands
at mucocuntaneous junctions, the skin is ____________ with mucous membranes that line ___________, __________, and ____________ tracts.
continuous
digestive, respiratory, urogenital
functions of the skin
protective barrier against:
- injury (abrasions, cuts, burns)*
- infectious pathogens*
- UV radiation
- body temp regulation*
- vitamin D synthesis
- ion excretion
- sensory reception*
why is vitamin D important?
helps with normalizing blood levels of calcium and phosphorous
what is an important quality of the skin?
it has a remarkable regenerative capacity
what type of epithelia is the integument composed of on the epidermis?
stratified squamous keratinized epithelium
the general organization of the layers of integument:
- epidermis
- dermis
- hypodermis
embryologically, what does the epidermis and its appendages derive from?
surface ectoderm
embryologically, what does the dermis derive from?
mesoderm
what is the skin composed of?
- keratinocytes (90%)
- melanocytes
- Merkel cells
embryologically, what does the Merkel cells and the melanocytes derive from?
the neural crest
which layer produces vitamin D?
the epidermis
- sunlight catalyzes the reaction of vitamin D3 production
schematic of skin and its appendages
what structures are included in the epidermis layer:
- hair shaft
- pore of sweat gland
what are the layers of the epidermis?
- stratum corneum
- stratum lucidum
- strautm granulosum
- stratum spinosum
- stratum basale
stratified corneum
- most superficial layer
- 20-30 layers
- cells are flat, dead, anucleated, and keratin filled karatinocytes
- protects against friction and water loss
stratum lucidum
- 2-3 layers of dead, anucleated cells
- only seen in thick skin
- see through
stratum granulosum
- 3-5 layers of keratinocytes
- distinct keratino-hyaline granules
stratum spinosum
- several layers of keratinocytes
- all joined by desmosomes (“spines”)
- when integument is fixed, they shrink but stay attached to desmosomes and appear to look like they have spines
- Langerhans cells present
stratum basale
- deepest, single layer
- cubodial to low columnar cells
- in contact with basement membrane
- mitosis occurs here
- has merkel and melanocytes
“germinal layer”
layers of the dermis
- papillary layer
- reticular layer
papillary layer of dermis
- more superficial layer of dermis
- composed of connective tissue
- forms dermal papillae
- contains subpapillary vascular plexus
reticular layer of dermis
- deeper layer of dermis
- dense irregular connective tissue
- surround hair follciles, sebaceous glands, sweat glands, nerves, deep plexus of blood vessels extending into subcutaneous layer
subcutaneous layers
- are not specific layers
- are not considered integument
- deep to dermis
- composed of adipose connective tissue
characteristics of thick skin:
- thick epidermis
- thick stratum corneum
- stratum lucidum
- no hair
- no arrector pilli
- no sebaceous glands
- many sweat glands
- dermatoglyphs (fingerprints)
where is thick skin located?
- palms/soles
- finger tips (dermatoglyphs)
characteristics of thin skin:
- thinner than thick skin
- thin stratum corneum
- no stratum lucidum
- hair
- arrector pilli
- sebaceous glands
- sweat glands
where is thin skin located?
everywhere but palms/soles
what is the key difference between thick and thin skin?
thick has stratum lucidum !! and thin does not
what layer can you find Meissner corpuscles?
DERMIS