Skin Structure & Function

Question 1

Bacterial dysbiosis

Answer 1

Allergic flare favoring opportunistic bacteria growth

Question 2

Lesion common in hyperadrenocosticism

Answer 2

Calcinosis cutis

Question 3

Lesion common with pancreatic tumor

Answer 3

Feline paraneoplasic alopecia

Question 4

Layers of skin effected by pemphigus foliaceus

Answer 4

Stratum granulosum and stratum spinosum

Question 5

Layers of skin effected by cutaneous lupus erythematosus

Answer 5

Stratum basale and basement membrane

Question 6

Stratum basale

Answer 6

Single row of cells resting on basement membrane
Constantly reproducing to replenish epi cells

Question 7

stratum spinosum

Answer 7

Composed of daughter cells fo stratum basale
Appear connected by intercellular bridges =spines
Thicker at footpads, nasal planum

Question 8

Stratum granulosum

Answer 8

Flattened cells, shrunk nuclei, contain keratohyalin granules**

Question 9

Composition of granules

Answer 9

Profilaggrins, loricrin, involucrin, caspase 14
Formation of SC, hydration of SC, filter UV radiation

Question 10

Stratum corneum

Answer 10

Composed of terminally differentiated keratinocytes
Usually dead layer
Inhibit microbial adherence, limits growth/number

Question 11

Corneocytes

Answer 11

Surrounded by extracellular lipid (bricks and mortar)
Provide hydration, physical barrier

Question 12

Cornification

Answer 12

Active process that requires ATP to transform stratum basale into stratum corneum

Question 13

Epidermal cell renewal time

Answer 13

Aka turnover rate
Time it takes for cells from basale cells to reach corneum. Dogs - 20-25d
Requires a delicate balance between cell death/renewal
Abnormal cornification - primary seborrhea of spaniels or zinc responsive dermatosis

Question 14

Desmosomes

Answer 14

Important for adhesion between keratinocytes
Help resist shearing forces
Ex pemphigus foliaceus

Question 15

Adherence junction

Answer 15

Mediates adhesion between keratinocytes

Question 16

Tight junction

Answer 16

Contributes to skin barrier function

Question 17

Gap junction

Answer 17

Intercellular routes of chemical communication

Question 18

Dermis is composed of

Answer 18

Fibers - collagen, elastin
Ground substance - proteoglycans, hyluronan
Cells - fibroblast, langerhans cells, mast cells
Epi appendages- sebaceous glands, hair follicles
Arrector pili muscles
Blood & lymph vessels
Nerves

Question 19

Sebaceous glands

Answer 19

Holocrine glands that open through a duct into the infundibulum
Secretes sebum over hair shaft/skin
Appearence, soft texture to hair/skin, permeability barrier, retain moisture

Question 20

Hair

Answer 20

Found only in mammals
Do not grow continuously but in cycles

Question 21

Simple hair follicle

Answer 21

One hair from one opening
Equine, bovine, procaine, ovien

Question 22

Compound hair follicles

Answer 22

Multiple hair follicles exit one hole
Canine, feline, ovine, caprine

Question 23

Hair growth cycle

Answer 23

Anagen - growing phase
Catagen - transition phase, signals end of active growth
Telogen - resting phase

Question 24

Function of hair

Answer 24

Physical barrier against trauma
UV protection
Thermoregulation/insulation
Repelling water
Sensation
Camouflage

Question 25

Specialized skin structure

Answer 25

Nasal planum Foot pad Claw

Question 26

Nasal planum

Answer 26

Color varies and can change overtime Cobblestone textures Shape and symmetry is important for function

Question 27

Diseases of nasal planum

Answer 27

Vitiligo Discoid lupus erythematosus Vasculitis

Question 28

Foot pad

Answer 28

Thick epidermis protect against mechanical trauma Large fat deposits provide shock absorption Abundant nerve supply Abundant sweat glands

Question 29

Problems w foot pad

Answer 29

Hyperkerotitc and crusting Ulcer Sloughing

Question 30

Claw

Answer 30

Composed of hard/soft keratins Growth rates influences by age, diet, environment, activity Claw disorder as the only dermatological manifestation of diseases are rare - trauma lipoid onychondystrophy

Question 31

Functions of claws

Answer 31

Grasping, prehensile Locomotion Defensive and offensive apparatus

Question 32

Disorders of claws

Answer 32

Lupoid onychodystrophy Onychocryptosis - ingrown claws

Question 33

SLO - canine symmetric lupoid onychondydrophy

Answer 33

Immune mediated disease that ONLY affects claws and nails Biopsy of affected nail beds revealed histological features seen in cutaneous lupus erythematosus

Question 34

Signalment/CS of SLO

Answer 34

Young to middle aged dogs Licking at paws, lameness, sloughing of claws Can affect one or more claws, often involve more than one paw

Question 35

DX and TX of SLO

Answer 35

Clinical signs Doxycycline + niacinamide Oral modified cyclosporine Fatty acid supplementation Pain meds as needed