Introduction and Skin Structure Flashcards
why is the barrier function of skin important?
regulates water loss, protects against mechanical, chemical, microbiological insults
what is the most important part of the skin for water loss prevention?
stratum corneum
what can chronic epithelial barrier dysfunction result in?
allergy development
what in skin protects cells against UV radiation?
melanin
how does skin serve an immunologic function?
senses and responds to external insults
contains many immune cells
develops innate and adaptive immune responses
what are damage-associated molecular patterns?
endogenous non-microbial molecules
released after tissue injury or cell death, stress
what does the skin microbiota do?
actively regulates innate immune responses
part of skin defense mechanisms
what are the recruited innate immune cells of the skin?
neutrophils
eosinophils
which cells bridge adaptive and innate immunity?
dendritic cells
how does the skin contribute to wound healing?
source of cells for re-epithelialization
what lies below the dermis?
subcutis/panniculus/hypodermis (fat)
what are the major layers of the epidermis?
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
what cells make up the majority of cells in the epidermis?
keratinocytes
what happens in canine pemphigus foliaceus?
autoantibodies target desmocollin-1
how frequent are melanocytes in the basal layer?
one per ten keratinocytes
what are melanocytes?
pigment-producing cells
transfer pigment/melanin to keratinocytes in basal layer
what is the epidermal melanin unit?
one melanocyte covers about 36 kertinocytes
what trace mineral is an essential cofactor for melanin synthesis?
copper
what are langerhans cells?
dendritic cells found in mid-epidermis
what is in the dermis?
fibroblasts
collagen bundles
resident immune cells
blood vessels
lymph vessels
hair follicles/adnexa
what is a simple hair follicle?
one primary hair follicle
what are the anatomic regions of a hair follicle?
infundibulum
isthmus
suprabulbar region
bulbar region
what are the main phases of the hair cycle?
anagen: growth
telogen: regression
what percentage of poodle hair follicles are anagen?
98%
what percentage of most breeds’ hair follicles are telogen?
38%
do primary hairs have nonseasonal or seasonal shedding?
nonseasonal shedding
what are the hair cycle factors in the environment?
circadian rhythm
photoperiod
nutrition
what are the hair cycle factors in the hair follicle?
dermal papilla
fibrous sheath
stem cells
connective and adipose tissues
during what time of day does hair grow faster?
in the morning
why does the hair follicle have immune privilege?
lack expression of MHC-I
expression of immunosuppressant molecules
lack langerhans- MHC-II
lack peribulbar lymphatics
what are the two sweat glands?
epitrichial (apocrine)
atrichial (eccrine)
what purposes does sebum serve?
physical and chemical barrier
antimicrobial
hydration
how do hormones affect sebaceous glands?
androgens: hypertrophy
estrogens/steroids: involution
where are epitrichial glands not present?
footpads
nasal planum
what glands are present in the footpads?
atrichial glands: sweat
what is albinism?
group of hereditary syndromes consequence of abnormalities in the synthesis of melanin
what are pathogen-associated molecular patterns?
highly conserved
sugars, proteins, lipids, nucleic acids
what do antimicrobial peptides do?
kill bacteria, fungi, viruses, parasites, neoplastic cells
mainly from keratinocytes
how does skin have nerve sensation?
sensory receptors and mechanoreceptors
what are keratinocytes held together by?
macromolecular structures that look like stripes between cells- desmosomes
primarily in spinous layer
what is the main function of langerhans cells?
afferent limb of immune response
recognition, uptake, processing, presentation to T-lymphocytes
delayed-type hypersensitivity
which hairs are seasonal and which ones are nonseasonal shedding?
primary: nonseasonal
secondary: seasonal
what time of day does hair grow fastest?
morning
are epitrichial glands involved in thermoregulation?
not commonly
