skin Flashcards
Describe the epidermis.
most superficial
keratinized stratified squamous epi.
derived from ectoderm
avascular
Describe the dermis.
deep
connective tissue
derived from mesoderm
highly vascularized
What is deep to the dermis?
Hypodermis (subcutaneous layer/fascia)
made of adipose tissue
What are the four main cells found in the epidermis and which is most prevalent?
Keratinocytes (most prevalent)
melanocytes
langerhan’s cells
merkel’s cells
Where is thick skin found?
palms of hands and soles of feet
From deep to superficial, what are the layers of the epidermis?
Stratum basale stratum spinosum stratum granulosum stratum lucidum (only thick skin) stratum corneum
What is the layer of epidermis only found in thick skin?
stratum lucidum
What is the role of keratinocytes?
- produce keratin, the major structural protein of skin
keratins form intermediate filaments (tonofilaments)
- form water barrier
How is the skin water proofed?
keratinocytes produce lamellar bodies which contain lipids
Describe the stratum basale.
- deepest layer
- single layer of cuboidal, basophilic cells
- mitotically active
Describe the stratum spinosum.
- thicker layer containing keratinocytes
- keratin intermediate fibers produced
- keratohyalin granules and lamellar bodies produced
How are keratinocytes held together?
desmosomes
Describe the stratum granulosum.
- intensely basophilic
- aggregation of tonofilaments into tonofibrils
- where keratinization takes place
Describe the stratum lucidum.
- only in THICK skin
- think translucent layer of eosinophilic cells
Descrice the stratum corneum.
- filled almost entirely with keratin
- cells are sloughed off
- no nuclei or organelles
What is the role of melanocytes and were are they found?
secrete melanin, which protects DNA from UV radiation
found within stratum basale, with dendritic extentions into stratum spinosum
What is the role of langerhan’s cells and where are they found?
cells present antigen to T lymphocytes
found in stratum spinosum
What is the role of merkel’s cells and where are they found?
mechanoreceptor cells associated w/ sensory nerve endings
found in stratum basale
What are the three major types of skin cancer?
basal cell carcinoma
squamous cell carcinoma
malignant melanoma
What is the most common skin cancer?
basal cell carcinoma
What are the two layers of the dermis?
papillary layer
reticular layer
What type of tissue is the papillary layer?
loose (areolar) CT
contains dermal papillae that project into epidermis
What type of tissue is the reticular layer?
dense irregular CT
What is the role of pacinian corpuscles and where are they found?
detect deep pressure and vibration
found in dermis and hypodermis (large and look like an onion)
What is the role of meissner’s corpuscles and where are they located?
detect light touch
found within dermal papillae of hairless skin (tapered cylindrical structures)
What muscle causes goosebumps? Is it smooth or skeletal? What innervates it?
arrector pili m.
smooth
sympathetic NS
What type of gland is an eccrine sweat gland? What is its mode of secretion? Where is it located?
simple coiled tubular
merocrine secretion onto skin surface
deep in dermis or upper part of hypodermis (all over body)
What type of gland is an apocrine sweat gland? What is its mode of secretion? Where is it located?
coiled tubular gland
merocrine secretion into hair follicles
located near hair follicle (upper party of hypodermis/deep dermis) in axillary and perineal regions
How do you tell the difference between eccrine and apocrine glands histologically?
apocrine glands have much larger secretory lumens
What type of gland is a sebaceous gland? What is its mode of secretion? Where is it located?
branched acinar gland
holocrine secretion (cell apoptosis)
located w/ hair follicle
