Exam 1 from notes Flashcards
What are the cuboidal cells in the stratum basale? Which predominates?
keratinocytes and melanocytes
90% keratinocytes
Which layer is the site of cell division?
stratum basale
What are the layers of the epidermis moving towards the surface?
basal, spinosum, granulosum, lucidum, corneum
better squares grow luscious corners!
What dynamic junctions attach keratinocytes to each other? What’s the significance of this?
desmosomes, can breakdown and allow other cells to pass through and keratinocytes to move
how are basal cells attached to the basement membrane?
hemidesmosomes
What is the autoimmune disease that targets desmosomes?
pemphigus foliaceus, most common autoimmune of domestic animals
What kind of skin is the stratum spinosum thicker in?
thicker in glabrous areas like footpads and nasal planum, only 1-3 layers in hairy skin
How do cells change shape in the stratum spinosum?
start polyhedral and flatten towards surface
What process begins in the stratum spinosum?
differentiation to become completely keratinized
What is acanthosis and what can cause it?
increased thickness of the stratum spinosum from chronic inflammation
Is the stratum granulosum present in all haired skin?
no where it is present it’s only 1-2 cells thick and twice as thick in glabrous skin
What do keratinocytes contain in the stratum granulosum? What are they’re significance?
keratohyalin granules rich in histidine and cystine
membrane coating granules that produce intercellular lipid for stratum corneum
Where is a stratum lucidum found? What kind of skin?
areas of friction where epidermis is thick
Cells of the stratum corneum are anuclear (T or F)
T, they are fully cornified
What constitutes the “brick and mortar” of the stratum corneum?
the fully keratinized keratinocytes are bricks and the intercellular lamellar lipid is the mortar
What is the cell envelope made of? And what is it’s function?
cross-linked proteins, structural support and barrier
What role do keratinocytes play in immunity?
they are phagocytic, produce cytokines and inflammatory mediators and antimicrobial peptides
What is the origin of melanocytes? Where are they found? What do they produce?
neural crest
in follicles, stratum basale, and glands
produce melanin to protect from UV light
What is the origin of langerhans cells? What is their function?
from bone marrow
immune surveillance, antigen presenting
What are the three stages of the epidermis life cycle?
mitosis, differentiation, exfoliation
Normal desquamation is visible on exam (T or F)
F, visible scales are a disorder of keratinization, increased mitosis -> reduced turn over time
Hairy skin has a thin epidermis with thin stratum corneum (T or F)
True, glabrous skin is thicker
Hairy skin does NOT have rete pegs (T or F)
True, glabrous skin has rete pegs
Skin is thickest over the ventrum, axillae, and inguinal regions (T or F)
False, in general skin is thickest over the dorsum (dorsal part of the animal)
What is the BMZ?
basement membrane zone, joins epidermis with underlying stroma
The dermis is the thickest part of the skin (T or F)
True
What are the 3 cells of the dermis?
fibroblasts, mast cells, and histiocytes
What do fibroblasts secrete?
fibronectin, collagen, elastic and reticular fibers
What are histiocytes?
dermal dendritic monocytes that can phagocytize
What is the name of a group of genetic disorders that involve defects in collagen synthesis?
Ehlers-Danlos Syndrome
Collagen is the major fiber of the dermis (T or F)
True, Collagen > Elastic > Reticulin
How do reticulin fibers differ from collagen?
fine and branching, take up silver stains
Where do arrector pili muscles originate?
BMZ and attach to base of hair follicle
What are the polysaccharides in the ground substance of the dermis?
glycosaminoglycans, linked to proteins as proteoglycans
What is found in large amounts in the dermis of Shar peis?
hyaluronic acid
What is the disease caused by abnormally high hyaluronic acid?
cutaneous mucinosis
Hypothyroidism can increase hyaluronic acid causing a condition called pitting edema (T or F)
False, it causes myxedema
What are the divisions of the dermis? And what is the characteristic of each?
papillary dermis (superficial) more cells and fibers reticular dermis (deep) course fibers and fewer cells
Hairy skin has dermal papillae (rete ridges) and well formed capillary loops (T or F)
False, Glabrous skin has these features, found at the foot pads and nasal planum
What is the function of the subcutis?
fat storage, insulation, body shape, shock absorber
What is sterile nodular panniculitis?
sterile inflammation of the subcutis with nodules
Sebaceous glands are present throughout haired skin (T or F)
True, empty into hair follicles
What three factors increase sebum production?
androgens, progesterone, and thyroid hormones
What two factors decrease sebum production?
corticosteroids and estrogen
Apocrine glands empty into hair follicles (T or F)
True
What is anhydrosis?
seen in horses that can’t sweat properly and result in hyperthermia
Eccrine glands empty into hair follicles (T or F)
False, found in hairless regions
Hair is made from soft keratin (T or F)
False, it’s made from hard keratin that is high in sulfur and cystine
What makes up the pilo sebaceous/apocrine apparatus?
hair follicle, sebaceous gland, apocrine gland
down growth of the epidermis
What are the three phases of hair growth?
anagen (growth), catagen (intermediate), telogen (resting)
Melanocytes of the hair bulb are always active (T or F)
False, only active during anagen
What hormone can initiate anagen?
thyroid hormone
What hormones can inhibit anagen?
glucocorticoids and estrogen
What is telogen defluxion?
couple months after a stressful event when lots of glucocorticoids were released, inhibits anagen -> many hairs stay in telogen
Describe a compound follicle.
multiple hairs emerging from a single hair follicle pore combo of primary and secondary follicles
Secondary follicles have apocrine glands and arrector pili just like primary follicles (T or F)
False, they lack these
The hair shaft is the entire length of the hair including the part below the skin surface (T or F)
False, it is the free portion above the skin, the root is the portion inside the follicle attached to the papilla by the hair bulb
What are the three layers of the hair?
cuticle, cortex, and medulla
What layers of the hair contains the melanin?
the cells of the cortex mostly, some in the medulla
All hairs have all three layers (T or F)
False, not all have a medulla
Compare primary hairs to secondary hairs
primary: large, medullated, coarse, guard hairs
secondary: fine, medullated, undercoat
What are lanugo hairs?
fine, non medullated, not present in dogs and cats post birth
Wool fibers don’t have a medulla (T or F)
True, fine non medullated and tightly crimped
Whiskers are what type of hair?
sinus or tactile hairs
Young animals are more commonly seen with auto immune and neoplastic skin diseases. (T or F)
False, more commonly allergies, demodicosis, dermatophytosis
endocrine, autoimmune, neoplasia in older animals
What colors in breeds predispose them to skin disease and what are some of the diseases?
any color dilution (blue or fawn) -> dilution alopecia
black -> black hair follicle dysplasia
The age of the animal at presentation is most important (T or F)
False, It’s important to get the age of onset in the history, often different from presentation
A dog that licks likely has severe pruritus (T or F)
False (usually), licking is often mild pruritus
chewing scratching and rubbing are moderate to severe signs
What does Dr. Torres list as her most important question to ask for history?
Is the animal pruritic? and how severe is it?
List some diseases that are always/typically pruritic.
atopic dermatitis food allergy flea bite allergy sarcoptic mange notoedric mange demodicosis by surface mite
List some diseases that are non-pruritic.
hypothyroidism cushing's alopecia sex hormone imbalance folliclular dysplasia decodicosis by follicular mite canine dermatophytosis
Which came first pruritus or alopecia or skin rash? What can the answer to this tell you?
itching first -> allergic or parasitic
alopecia first -> endocrinopathy or demodicosis
skin rash first -> bacterial, underlying endocrine, sterile pustular
Previous treatment isn’t important in a history (T or F)
False (duh!), Dr. Torres says this is extremely important! Was it used at the right dosage for the proper duration?
What would you suspect with a very pruritic dog that doesn’t respond to glucocorticoids? What disease usually responds well to glucocorticoids?
suspect sarcoptic mange
allergic dogs should respond well to glucocorticoids suppress immune response -> less hypersensitivity
What would you suspect if a dog becomes worse with glucocorticoids?
parasitic or infectious causes
suppress immune response -> can’t fight off
What should you do if pyoderma doesn’t respond to emperical antibiotics?
culture and sensitivity!
Macules can be palpated (T or F)
False, it cannot, it is a flat change in skin color
What is a patch?
a macule greater than 1 cm
What are the 4 differentials for a macule?
depigmented, melanotic, erythematous, hemorrhagic
What is a papule?
solid elevation up to 1 cm
Papules can always be palpated (T or F)
True, a solid mass of inflammatory cells
What are common differentials for papules?
superficial pyoderma (until proven otherwise)
parasites (sarcoptic)
bacterial
flea allergy
What is a plaque?
large flat topped elevation or coalition of papules
What are differentials for plaques?
eosinophil plaques
fungal
neoplasm
What is a nodule?
solid elevation over 1 cm
What are differentials for a nodule?
deep fungal
neoplasm
panniculitis
sterile pyogranulomas
Tumors can involve any structure of the skin (T or F)
True
What is a pustule?
small elevation filled with pus, usually yellow
Pustules are hard to rupture (T or F)
False, easily rupture because they are superficial and result in crusts
What are differentials for pustules?
superficial pyoderma
demodicosis
pemphigus foliaceous
Abscesses are very superficial and pus is easily seen (T or F)
False, large and deep
pus isn’t seen until it drains to surface
What is the primary differential for an abscess?
bacterial infection
Vesicles are filled with pus (T or F)
False, filled with clear fluid
What are differentials for vesicles?
autoimmune
viral
chemical irritant
What is a bulla?
a vesicle over 1cm
What is a cyst?
epithelial lined cavity of fluid
What is a wheal?
short lived raised lesion of edema
What is angioedema and what is a defining characteristic?
diffuse edema extending into the subcutis
pits when pressed
What is a scale?
loose fragments of the stratum corneum
What is erythema and what happens when you press it?
diffuse red discoloration, blanches when pressed
What does concurrent inflammation with alopecia tell you?
inflammation present ->allergic or parasitic
absent -> endocrinopathies or follicular dysplasia (alopecia is spontaneous not self induced)
What is a follicular cast and what is the primary differential?
keratin and follicular material that adheres to the shaft
sebaceous adenitis
What is a crust?
dried exudate
What is a comedo?
dilated follicle filled with keratin and sebum (blackhead)
What are comedones a primary lesion of?
feline acne
hypothyroid
cushing’s
What is an erosion?
shallow break in continuity of epidermis, doesn’t penetrate stratum basale, heals without scarring
Erosions are deeper than ulcers (T or F)
False, ulcers are deeper and expose underlying dermis, usually scars
Excoriations are spontaneous (T or F)
False, they are self induced linear erosions or ulcers from scratching etc
What is an epidermal collarette?
circular rim of loose keratin
What does an Epidermal collarette usually indicate?
superficial staph infection, superficial spreading pyoderma
Lichenification indicates chronic inflammation (T or F)
True, result of friction
What are ulcerated tracts in the skin originating in the deep dermis or subcutis fat?
draining sinus tracts
What is a fissure and its pathogenesis?
linear cleavage of epidermis
thick inelastic skin -> sudden swelling or trauma
If you see blood when doing a skin scraping you’ve gone too far (T or F)
False, you want to see a small amount of blood in an adequate scraping
Always scrape excoriated areas (T or F)
False, mites are mechanically removed anyway
scrape papules
Compare direct smears to impression smears
direct smears: collect material with a needle
impression smears: slide is pressed to the lesion
When doing a punch biopsy you want to get normal and abnormal skin (T or F)
False, just lesional skin
lesions may be small and you don’t want to have only normal skin in your biopsy
