Skin Flashcards
Name the 3 zones of skin
epidermis
dermis
subcuticular/hypodermis
What are the functions of skin?
environmental barrier temperature regulation immunological mechanical support neurosensory metabolic/endocrine glandular secretion
What are the main features of epidermis?
stratified squamous cells
not vascularized
List the layers of epidermis from most internal to external.
basement membrane stratum basale stratum spinosum stratum granulosum (stratum lucidum) stratum corneum
Describe the main characteristics of the stratum basal
columnar/cuboidal stem cells
migrate outwards & keratinize
What are the main general characteristics of cells within the stratum spinosum?
polyhedral
connected via desmosomes
What are the main characteristics of cells in the stratum granulosum?
flattened
keratohyalin & lamelar granules
Describe the general characteristics of the stratum lucidum.
not everywhere
thin & translucent
no nuclear detail
Describe the stratum corneum.
variable # of dead keratinized cells
Describe the keratinization process
keratinocytes increase in size synthesize granules nuclei disintegrate lamellar granules release lipids to extracellular spaces cells flatten
What are langerhans cells? What is their main function? Where are they located?
antigen presenting cells
stratum spinosum
move to dermis for immune function
Describe the basic characteristics & function of melanocytes.
pigmented melanosome granules
stratum basal
melanosomes migrate & are phagocytosed by adjacent keratinocytes
Describe the main characteristics of merkel cells.
stratum basal
vacuolated cytoplasm on dermal side
mechanoreceptors
How does the basement membrane function?
stratum basal attached to BM by hemidesmosomes
structural integrity of skin
List some inclusions within the dermis.
lymphatics blood vessels nerves adnexae (epidermal inclusions within dermis) collagen bundles inflammatory cells
Describe the structure and inclusions of the hypodermis.
adiposites
anchors dermis to muscle
less collagen, more BV
What are dermal papillae?
adhesion between dermis & epidermis
nourishment of epidermis
What are the layers of the dermis?
papillary dermis
reticular dermis
What are Meissner’s corpuscles?
mechanoreceptors in hairless skin
List the 3 main components of hair.
medulla
cortex
cuticle
Where are the hair follicles?
in dermis, sometimes hypodermis
What are some hair related inclusions in the dermis?
inner root sheath
external root sheath
dermal papilla
hair matrix
Describe the hair cycle
anagen - mitotically active follicle
catagen - follicle migrates up & becomes column of cells
telogen - resting, no growth, base @ sebaceous canal
What is the function of a primary hair follicle?
produce guard hair
What are the characteristics of secondary hair follicles?
closer to skin
no sweat gland
underhairs
Simple hair follicles have ___.
one hair
Compound hair follicles have ___.
multiple hairs
multiple follicles fused @ sebaceous gland
Cat skin has what types of follicles?
simple & groups of compound
Sheep have ___ hair follicles
simple (hair)
compound (wool)
Equine & bovine hair follicles can be described as __.
single & evenly distributed
Pigs have ____ hair follicles
single clustered
What are sinus hairs?
whiskers
surrounded by blood-filled sinus with muscle attached to sheath
lots of nerve bundles associated with sheath
Function of sinus hairs
perception of touch
voluntary control
What are the 2 types of skin glands?
sebaceous
sweat
Sebaceous cells look like
large
foamy
Sweat gland looks like
simple cuboidal
“empty” cavity in middle
Sebum functions as ___.
antibacterial
waterproofing
What is the method of excretion for sebaceous glands?
holocrine
What is the excretion method of sweat glands?
merocrine
apocrine
Describe the structure of apocrine sweat glands.
coiled secretory & straight duct
evenly distributed
cuboidal & columnar
Describe the excretion method and location of merocrine sweat glands
specialized areas (footpads/frog)
open directly onto skin
simple cuboidal, associated with myoepithelial
What are Meibomian glands?
eyelid
with duct opening directly to eye
What and where are Ciliary glands?
apocrine sweat glands
open to eyelash follicles
Epithelium in nose?
thick stratified squamous
deep grooves (not in cattle)
no hair follicles
Describe claws
continuous with epidermis
hard keratin sheath
soft dermis with blood supply
