Introduction and Skin Structure

Question 1

why is the barrier function of skin important?

Answer 1

regulates water loss, protects against mechanical, chemical, microbiological insults

Question 2

what is the most important part of the skin for water loss prevention?

Answer 2

stratum corneum

Question 3

what can chronic epithelial barrier dysfunction result in?

Answer 3

allergy development

Question 4

what in skin protects cells against UV radiation?

Answer 4

melanin

Question 5

how does skin serve an immunologic function?

Answer 5

senses and responds to external insults
contains many immune cells
develops innate and adaptive immune responses

Question 6

what are damage-associated molecular patterns?

Answer 6

endogenous non-microbial molecules
released after tissue injury or cell death, stress

Question 7

what does the skin microbiota do?

Answer 7

actively regulates innate immune responses
part of skin defense mechanisms

Question 8

what are the recruited innate immune cells of the skin?

Answer 8

neutrophils
eosinophils

Question 9

which cells bridge adaptive and innate immunity?

Answer 9

dendritic cells

Question 10

how does the skin contribute to wound healing?

Answer 10

source of cells for re-epithelialization

Question 11

what lies below the dermis?

Answer 11

subcutis/panniculus/hypodermis (fat)

Question 12

what are the major layers of the epidermis?

Answer 12

stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale

Question 13

what cells make up the majority of cells in the epidermis?

Answer 13

keratinocytes

Question 14

what happens in canine pemphigus foliaceus?

Answer 14

autoantibodies target desmocollin-1

Question 15

how frequent are melanocytes in the basal layer?

Answer 15

one per ten keratinocytes

Question 16

what are melanocytes?

Answer 16

pigment-producing cells
transfer pigment/melanin to keratinocytes in basal layer

Question 17

what is the epidermal melanin unit?

Answer 17

one melanocyte covers about 36 kertinocytes

Question 18

what trace mineral is an essential cofactor for melanin synthesis?

Answer 18

copper

Question 19

what are langerhans cells?

Answer 19

dendritic cells found in mid-epidermis

Question 20

what is in the dermis?

Answer 20

fibroblasts
collagen bundles
resident immune cells
blood vessels
lymph vessels
hair follicles/adnexa

Question 21

what is a simple hair follicle?

Answer 21

one primary hair follicle

Question 22

what are the anatomic regions of a hair follicle?

Answer 22

infundibulum
isthmus
suprabulbar region
bulbar region

Question 23

what are the main phases of the hair cycle?

Answer 23

anagen: growth
telogen: regression

Question 24

what percentage of poodle hair follicles are anagen?

Answer 24

98%

Question 25

what percentage of most breeds' hair follicles are telogen?

Answer 25

38%

Question 26

do primary hairs have nonseasonal or seasonal shedding?

Answer 26

nonseasonal shedding

Question 27

what are the hair cycle factors in the environment?

Answer 27

circadian rhythm photoperiod nutrition

Question 28

what are the hair cycle factors in the hair follicle?

Answer 28

dermal papilla fibrous sheath stem cells connective and adipose tissues

Question 29

during what time of day does hair grow faster?

Answer 29

in the morning

Question 30

why does the hair follicle have immune privilege?

Answer 30

lack expression of MHC-I expression of immunosuppressant molecules lack langerhans- MHC-II lack peribulbar lymphatics

Question 31

what are the two sweat glands?

Answer 31

epitrichial (apocrine) atrichial (eccrine)

Question 32

what purposes does sebum serve?

Answer 32

physical and chemical barrier antimicrobial hydration

Question 33

how do hormones affect sebaceous glands?

Answer 33

androgens: hypertrophy estrogens/steroids: involution

Question 34

where are epitrichial glands not present?

Answer 34

footpads nasal planum

Question 35

what glands are present in the footpads?

Answer 35

atrichial glands: sweat

Question 36

what is albinism?

Answer 36

group of hereditary syndromes consequence of abnormalities in the synthesis of melanin

Question 37

what are pathogen-associated molecular patterns?

Answer 37

highly conserved sugars, proteins, lipids, nucleic acids

Question 38

what do antimicrobial peptides do?

Answer 38

kill bacteria, fungi, viruses, parasites, neoplastic cells mainly from keratinocytes

Question 39

how does skin have nerve sensation?

Answer 39

sensory receptors and mechanoreceptors

Question 40

what are keratinocytes held together by?

Answer 40

macromolecular structures that look like stripes between cells- desmosomes primarily in spinous layer

Question 41

what is the main function of langerhans cells?

Answer 41

afferent limb of immune response recognition, uptake, processing, presentation to T-lymphocytes delayed-type hypersensitivity

Question 42

which hairs are seasonal and which ones are nonseasonal shedding?

Answer 42

primary: nonseasonal secondary: seasonal

Question 43

what time of day does hair grow fastest?

Answer 43

morning

Question 44

are epitrichial glands involved in thermoregulation?

Answer 44

not commonly