Skin Structure & Function Flashcards
Bacterial dysbiosis
Allergic flare favoring opportunistic bacteria growth
Lesion common in hyperadrenocosticism
Calcinosis cutis
Lesion common with pancreatic tumor
Feline paraneoplasic alopecia
Layers of skin effected by pemphigus foliaceus
Stratum granulosum and stratum spinosum
Layers of skin effected by cutaneous lupus erythematosus
Stratum basale and basement membrane
Stratum basale
Single row of cells resting on basement membrane
Constantly reproducing to replenish epi cells
stratum spinosum
Composed of daughter cells fo stratum basale
Appear connected by intercellular bridges =spines
Thicker at footpads, nasal planum
Stratum granulosum
Flattened cells, shrunk nuclei, contain keratohyalin granules**
Composition of granules
Profilaggrins, loricrin, involucrin, caspase 14
Formation of SC, hydration of SC, filter UV radiation
Stratum corneum
Composed of terminally differentiated keratinocytes
Usually dead layer
Inhibit microbial adherence, limits growth/number
Corneocytes
Surrounded by extracellular lipid (bricks and mortar)
Provide hydration, physical barrier
Cornification
Active process that requires ATP to transform stratum basale into stratum corneum
Epidermal cell renewal time
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
Desmosomes
Important for adhesion between keratinocytes
Help resist shearing forces
Ex pemphigus foliaceus
Adherence junction
Mediates adhesion between keratinocytes
Tight junction
Contributes to skin barrier function
Gap junction
Intercellular routes of chemical communication
Dermis is composed of
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
Sebaceous glands
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
Hair
Found only in mammals
Do not grow continuously but in cycles
Simple hair follicle
One hair from one opening
Equine, bovine, procaine, ovien
Compound hair follicles
Multiple hair follicles exit one hole
Canine, feline, ovine, caprine
Hair growth cycle
Anagen - growing phase
Catagen - transition phase, signals end of active growth
Telogen - resting phase
Function of hair
Physical barrier against trauma
UV protection
Thermoregulation/insulation
Repelling water
Sensation
Camouflage
Specialized skin structure
Nasal planum
Foot pad
Claw
Nasal planum
Color varies and can change overtime
Cobblestone textures
Shape and symmetry is important for function
Diseases of nasal planum
Vitiligo
Discoid lupus erythematosus
Vasculitis
Foot pad
Thick epidermis protect against mechanical trauma
Large fat deposits provide shock absorption
Abundant nerve supply
Abundant sweat glands
Problems w foot pad
Hyperkerotitc and crusting
Ulcer
Sloughing
Claw
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
Functions of claws
Grasping, prehensile
Locomotion
Defensive and offensive apparatus
Disorders of claws
Lupoid onychodystrophy
Onychocryptosis - ingrown claws
SLO - canine symmetric lupoid onychondydrophy
Immune mediated disease that ONLY affects claws and nails
Biopsy of affected nail beds revealed histological features seen in cutaneous lupus erythematosus
Signalment/CS of SLO
Young to middle aged dogs
Licking at paws, lameness, sloughing of claws
Can affect one or more claws, often involve more than one paw
DX and TX of SLO
Clinical signs
Doxycycline + niacinamide
Oral modified cyclosporine
Fatty acid supplementation
Pain meds as needed
