General Boards Flashcards
What percentage of the body is fluid? What is the split of this amount between the intra and extracellular space?
60% of body weight is fluid
1/3 is in the extracellular space
2/3 is in the intracellular space
What ions are predominantly in the extracellular space, and what ions are predominantly in the intracellular space?
Extra - sodium, chloride, calcium, bicarbonate
Intra - potassium, phosphate, magnesium, proteins
Which organelle doesn’t have a membrane / phospholipid bilayer?
The nucleoulus - just an accumulation of RNA and proteins
What do the RER and SER manufacture, respectively
RER - proteins
SER - lipids
What organelle forms the nuclear membrane?
Endoplasmic reticulum
What organelle produces hyaluronic acid and chondroitin sulfate? What are these molecules?
The Golgi apparatus
Large saccharide polymers attached to a small protein backbone
What type of bond holds together the two strands of DNA? Is it strong or weak? What nucleotides bind together?
Weak, hydrogen bonds
Adenine bases bond with thymine
Cytosine bases bond with guanine
What is the term for the 3 adjacent nucleotides that determine the specific amino acid included in a future protein molecule?
Codon
What is the term for proteins that span the width of the cell membrane?
Integral proteins
What are four substances that have a high lipid solubility and can easily cross cell membranes?
Oxygen
Carbon dioxide
Nitrogen
Alcohol
What structures allow the free diffusion of water across lipophilic cell membranes?
Aquaporins
Via what type of transport mechanism does glucose use to get into cells from the bloodstream? What are the transport proteins called? Which transport protein is insulin-dependent?
Facilitated diffusion
GLUT transport proteins
GLUT-4
Definition for osmolality
Definition for osmolarity
Osmolality — osmoles in kilogram of water
Osmolarity — osmoles in liter of solution (ie the body)
These are essentially equivalent in the body given that the fluid in the body is almost all water.
Three functions of the Na-K-ATPase pump
- Maintain intra/extracellular concentration gradients of Na and K
- Establish negatively charged intracellular voltage gradient
- Maintain cell volume (via ions)
How much more calcium is located extracellularly compared to intracellularly?
How is this gradient maintained?
10,000 x
There is a calcium-ATPase pump in the cell membrane, and there is a similar pump located in certain organelles (sarcoplasmic reticulum - SERCA, mitochondria) that keeps the calcium levels in the intracellular fluid low.
What are two places in the body where active transport of hydrogen ions occurs?
What is the name of this pump?
Parietal cells in the stomach (for formation of HCl)
Alpha Intercalated cells in the distal tubules / collecting ducts of the nephron (excretion of excess H+ in the urine)
H+ - K+ - ATPase pump (proton pump)
What is the resting membrane potential of neurons, and how much is contributed by the Nernst potentials of Na and K, and how much is contributed by the Na-K-ATPase pump?
-90 mV
-86 mV is contributed to by the Nernst potentials
-4 mV is contributed to by the Na-K-ATPase pump
What ion alters the sensitivity of the voltage gated sodium channels, and what do high and low levels of this ion cause?
Calcium
High calcium - difficult to activate the VGSC
Low calcium - easy to activate the VGSC —> tetany / eclampsia
What is the functional unit of muscles?
Define the different parts of this structure.
Sarcomeres - one z line to another
I band - where there is just actin (immediately adjacent to z line)
A band - where there is myosin and actin overlapping, more centrally located
M line - center of A band
What protein helps hold myosin and actin in proximity to each other?
Titin
Explain how calcium allows for muscle contraction.
Calcium binds to troponin. This shifts the tropomyosin bands associated within the actin filaments to expose the active sites on the actin bands. Once the active sites are exposed, then the myosin heads can bind to them, and pull the actin filaments inwards, shortening the sarcomere (ie contraction)
What are the other names for fast and slow muscle fibers, and what are some distinguishing criteria between the two types?
Type 1 - slow
1. Good blood supply
2. Rely on oxidative metabolism
3. Have large amounts of myoglobin (red)
4. Lots of mitochondria
5. Smaller fibers / smaller nerve fibers
Type 2 - fast
1. Less blood supply
2. Rely more on anaerobic metabolism / glycolysis
3. Minimal myoglobin (white)
4. Less mitochondria
5. Large fibers with extensive sarcoplasmic reticulum
What are the receptors located in the skeletal muscle sarcoplasmic reticulum that release calcium when triggered by an AP called?
Ryanodine receptors
The presence of what channel results in the plateau phase of the action potential of cardiac muscle, compared to the short AP of skeletal muscle?
Slow calcium channels
What does the strength of cardiac contractability depend on primarily?
Concentration of extracellular calcium
The ____________ calcium concentration is more important for skeletal muscle conduction because most calcium is released from __________.
The ____________ calcium concentration is more important for cardiac muscle contraction, as most calcium enters the cardiac myocytes via the __________.
Intracellular, sarcoplasmic reticulum
Extracellular, T tubules
What is the AV node delay designed for?
To allow the atria to contract prior to ventricular contraction, resulting in more blood in the ventricle when it does contract (ventricular priming).
What is the difference between the VGSC in the pacemaker cells of the heart versus the true myofibers?
The VGSCs of the pacemaker cells are more leaky than those in the muscle. This allows for a slow, steady depolarization of the cell (with the help of slow calcium channels) following repolarization. The VGSCs of the cardiac myofibers are quick to shut and not leaky.
This difference also explains the difference in RMPs between these two cell types.
What is the RMP for the pacemaker cells in the heart, and for the cardiac myofibers?
Pacemaker cells: -55 to -60 mV
Cardiac myofibers: -90 mV
What cellular feature results in the AV nodal delay?
Less gap junctions in the AV node, forces the signal to travel slower between the cells
How does stimulation of the vagus nerve decrease heart rate?
It results in release of ACh at the SA node, which increases permeability of the node to potassium, making the RMP more negative. This means we have to wait longer for the leaky sodium (and calcium) channels to depolarize back to threshold from this more negative RMP (thus making each heart beat take longer to happen).
Why do we observe a ventricular repolarization T wave, but not an equivalent finding for the atrial repolarization?
The atrial repolarization wave occurs during ventricular depolarization, and is therefore hidden by the QRS complex.
What percentage of dogs with MMVD have tricuspid valve involvement?
30%
What are the four criteria that distinguish between a B1 and B2 MMVD patient?
- Murmur > 3/6
- Elevated LA:Ao ratio (>1.6)
- Elevated LVIDDn (>1.7)
- Elevated VHS (>10.5)
How do you measure VLAS?
Either right or left lateral projection.
Line from ventral most aspect of carina to the intersection of the left atrium and the dorsal border of the caudal vena cava.
What blood test can be used in dogs and cats to help determine if clinical signs of heart failure are truly related to heart failure or not?
NT-proBNP concentrations (normal / near normal results make CHF unlikely)
What dose of furosemide needs to be reached prior to considering a dog as stage D MMVD?
8 mg/kg/d
Which retinal cell layer provides the axons that form the optic nerve?
Ganglion cells
What are the receptors for light in the eye?
Which receptors are more sensitive to light, and which have better acuity / detail?
The cones and rods.
The cones have better acuity - they synapse on just one bipolar cell (which then synapses one just one ganglion cell).
The rods have better sensitivity to light - they synapse into multiple bipolar cells, which then activate many ganglion cells (which then travel as the optic nerve).
Information from which side of retina crosses at the optic chiasm?
Nasal portions, which perceive information from the lateral (temporal) planes.
What transport protein is located in both the thick ascending loop of Henle and the stria vascularis of the inner ear?
Na-2Cl-K cotransporter
Loop diuretics that inhibit this protein can result in deafness via changes in the electrolyte concentration of the endolymph.
What are the four most common skin tumors of cats?
Basal cell tumors
Mast cell tumors
Squamous cell carcinoma
Fibrosarcoma
Most common skin tumor in dogs
Mast cell tumor
What locations impart a worse prognosis for melanomas?
Digit and oral cavity, more likely to be malignant
What is a squamous cell carcinoma in situ, and what is it called when one develops secondary to excessive UV radiation?
It is a SCC that has not crossed beneath the basement membrane of the epithelium.
Actinic keratosis
What is the most common malignant neoplasm of the ear in dogs and cats?
Ceruminous gland adenocarcinoma
What is the most common malignant neoplasm of the digit, and in what type of dog is it most common in?
Squamous cell carcinoma
Black haired dogs
Digit tumors in cats have a high (~90%) chance of being what?
Metastatic from the lungs (lung-digit syndrome)
What is the most common oral tumor in dogs?
Melanoma
Mutations in this gene has been associated with worse prognosis in mast cell tumors?
What class of proteins is created by this gene?
C-kit
Tyrosine kinase receptor — this allows for cell proliferation and differentiation. The mutation allows this receptor to function independent of its ligand.
What is the most reliable prognostic factor for canine MCTs?
Histologic grade (low, intermediate, high)
What stains can be used to highlight mast cell granules in those MCTs that don’t stain with traditional H&E / diff quik stains?
Wright Giemsa
Toluidine blue
What breed of dog tends to have more benign acting MCTs?
Boxers
What are some side effects of toceranib phosphate?
Bone marrow suppression (leuko mostly)
GI (vomiting, diarrhea, hyporexia)
Hypertension
Proteinuria
Muscle pain
Which subtype of histamine receptors are present in the stomach?
H2
What are the 3 clinical syndromes of MCTs in cats?
- Cutaneous
- Visceral / splenic
- Intestinal
What is a unique subtype of feline MCTs?
Histiocytic - can occur in young cats, and also regress spontaneously
Most common cause of splenic disease in cats
Mast cell tumor
40-100% of cases are associated with a peripheral mastocytosis
What infectious agent can cause soft tissue sarcoma development?
What types of sarcoma?
What is the main location?
What other radiographic sign can be detected?
Spirocerca lupi
OSA, FSA, undifferentiated
Caudal thoracic esophagus
Ventral spondylitis from T6-T12
What is the main STS to occur in young dogs?
Rhabdomyosarcoma
Nerve sheath neoplasms can arise from what cell types?
Schwann cells
Perineural cells
Perineural or endoneural fibroblasts
Nerve sheath neoplasms can be differentiated from perivascular wall tumors via what stains?
S-100, vimentin, GFAP, nerve growth factor receptor, and neuron specific enolase.
What is the most common location of intermuscular lipomas? (what muscles do they arise in between?)
Caudal thigh in between the semitendinosus and semimembranosus muscles.
What type of biopsy procedure is not recommended for soft tissue sarcomas?
Excisional biopsy
Suggested margins for STS removal
2-3 cm lateral, 1 facial layer deep
What are the recurrence rates for incompletely excised grade I and II STSs, and what is the clinical implication of this?
Grade I — 7%
Grade II — 34%
Incomplete excisions of these tumors could be amenable to active surveillance as there is a relatively high chance that they may not recur.
What is the site of highest resistance in the circulatory system? What controls this resistance?
The arterioles
The autonomic nervous system
(Alpha 1 innervation to the arterioles of skin, splanchnics, and renal, beta 2 to arterioles of the skeletal muscle)
What two types of blood vessels are supplied by alpha 1 receptors?
Arterioles of skin, splanchnics, and kidneys
Veins (unspecified)
What are arterial murmurs called?
Bruits
What portion of the heart does not have parasympathetic innervation?
Ventricles
What is the formula for ejection fraction, and what is a normal EF?
Stroke volume / end diastolic volume
55-60%
What is the mechanism of action for cardiac glycoside medications?
Na-K-ATPase pump inhibition —> reduced Na gradient —> less activity of the Na-Ca exchanger —> accumulation of intracellular Ca —> stronger heart muscle contraction
Positive inotrope
What do S3 and S4 heart sounds refer to? What disease states in dogs / cats can cause these? What is it called when one is heard?
S3 — occurs immediately after ventricular systole (aka onset of ventricular diastole); large volume of blood in the atria rapidly entering the ventricle
S4 — occurs during atrial systole; ejection of atrial blood into the ventricle
S3 can be heard in dogs with DCM, and S4 can be heard in cats with HCM.
Gallop rhythm
What cranial nerve innervates the baroreceptors in the carotid sinus / carotid bifurcation?
Cranial nerve IX via the carotid sinus nerve
Action of aldosterone on Na and K?
Save sodium
Pee potassium
What are four actions of angiotensin II?
- Increase aldosterone secretion
- Increase Na-H antiporter activity in proximal tubule
- Increase thirst
- Arteriolar vasoconstricter
What three organs demonstrate auto regulation?
Heart
Brain
Kidneys
How do substances like histamine and bradykinin result in edema?
They cause arterial vasodilation and venous vasoconstriction
What is the most important determinant of cerebral bloodflow?
Why don’t other factors play a role?
Carbon dioxide —> elevated levels cause vasodilation
The blood brain barrier
Most common oral tumor
- Dog
- Cat
Dog: malignant melanoma
Cat: squamous cell carcinoma
For oral SCC, does the potential for metastasis increase or decrease as you move rostral to caudal?
Increase
What oral tumor commonly occurs between the canines and carnassial teeth, and what is a unique feature of this tumor?
Fibrosarcoma
They often appear histologically benign, but exhibit locally aggressive behavior
What is the main difference between peripheral odontogenic fibromas and acanthomatous ameloblastomas?
POF do not invade bone while AA do.
What form of SCC is highly metastatic?
Tonsillar SCC
What percent of all OSAs involve the axial skeleton?
25%
Which has a better prognosis: mandibular OSA or maxillary OSA?
Mandibular
What tumor of the tongue has a good prognosis even with marginal surgical resection?
Granular cell myoblastoma
What are some characteristic features of “undifferentiated malignancy of young dogs”?
- occurs in dogs under 2 years of age
- rapidly growing mass in the upper oral cavity / orbit
- high metastatic rate
- most dogs euthanized in 1 month after diagnosis
What location carries the best prognosis for MLO?
Mandible (~1500 days)
Most common type of salivary gland tumor
Adenocarcinoma
What is a unique paraneoplastic syndrome of pancreatic adenocarcinoma in the cat?
Alopecia
What is the pathophysiologic mechanism behind paraneoplastic hypoglycemia with leiomyo(sarco)mas?
secretion of insulin-like growth factor 2
What cell type do GISTs arise from, and what do the commonly express? What is the clinical significance of this?
Interstitial cells of Cajal
Commonly express c-kit and CD34
Helps distinguish from smooth muscle tumors
What is the main morphologic difference between gastric carcinomas and mesenchymal gastric tumors?
Carcinoma - broad based
Mesenchymal - focal / pedunculated
Most common hepatic tumor in dogs, cats?
Dogs - HCC
Cats - biliary cystadenoma (biliary duct adenoma)
What breed of dog is over-represented for HCC, and what breed of dog has a link with vacuolar hepatopathy?
- Miniature schnauzer
- Scottish terriers
Four main hepatic tumors in dogs and cats?
Three main distributions?
- Hepatocellular carcinoma
- Biliary duct tumors
- Neuroendocrine
- Mesenchymal / sarcomas
- Massive
- Nodular
- Diffuse
What are three reasons for a patient with a hepatic mass to present with neurologic signs?
- Hepatic encephalopathy
- Paraneoplastic hypoglycemia
- CNS metastasis
Which division for HCC carries a worse prognosis and why?
Right sided, surgical manipulation of the caudal vena cava
Most common and second most common intestinal tumor in dogs and cats
Lymphoma
Adenocarcinoma
What location along the GI tract is more likely to develop a GIST or leiomyo(sarco)ma than an adenocarcinoma?
The cecum
What is a carcinoid?
Neuroendocrine tumor of the GI tract, arising from the endocrine cells in the GIT. They are histologically similar to carcinomas, but contain secretory granules.
They are highly aggressive.
What perianal tumor in dogs is androgen related, and why can this tumor occur in female dogs occasionally?
Perianal (hepatoid) tumors
Hyperadrenocorticism
What is the major difference regarding treatment for perianal gland adenocarcinoma and adenoma?
Castration does not make a difference for adenocarcinomas because they are not testosterone induced.
How much of the anal sphincter can be removed without causing significant fecal incontinence?
~50%
True or false - size of a primary AGASACA is positively correlated with metastatic potential
False - very small tumors can met, while large ones often don’t. Regional lymph node metastases are the most common.
What percentage of dogs with AGASACA have bilateral tumors (either simultaneously or temporally)? Cats?
Dogs 15%
Cats 0%
What are two distinguishing characteristics of AGASACA cytology?
- Classic ‘neuroendocrine’ look
- Minimal criteria of malignancy
What tumor type has a significant survival benefit with lymph node extirpation?
AGASACA
What muscles are part of inspiration and what are part of expiration?
Inspiration - diaphragm and external intercostals
Expiration - abdominal muscles and internal intercostals
What is different about fetal and adult hemoglobin? Why is fetal hemoglobin like this?
Fetal hemoglobin is composed of gamma subunits instead of beta ones (a2y2 v a2b2). This makes fetal hemoglobin less susceptible to binding to 2,3-DPG, and thus it binds tighter to oxygen.
The point of this is so that oxygen can get passed from the mother to fetus.
What things shift the oxygen-hemoglobin association curve to right? To the left?
To the right (reduced hemoglobin binding): decreased pH, increased CO2, increased temperature, increased 2,3-DPG
To the left (increased hemoglobin binding): increased pH, decreased CO2, reduced temperature, less 2,3-DPG, fetal hemoglobin
What are five causes of hypoxemia?
Which ones have a normal A-a gradient, and which don’t?
What is A-a gradient?
- Decreased FiO2 - normal Aa gradient
- Hypoventilation - normal Aa gradient
- V/Q mismatch - increased Aa gradient
- Diffusion impairment - increased Aa gradient
- Right to left shunt - increased Aa gradient
A-a gradient = PAO2 (alveolar) - PaO2 (arterial); normal is 0-10 mmHg
Five causes of hypoxia
- Hypoxemia
- Decreased cardiac output
- Anemia
- CO poisoning
- Cyanide poisoning
What is the last anatomic portion of the conducting zone and the first anatomic portion of the respiratory zone?
What happens here in regards to gas transport? Why?
Terminal bronchioles
Respiratory bronchioles
The forward velocity of inspired gas slows dramatically. Movement of gas from here forward primarily relies on diffusion. It happens because the cross sectional area of the lungs dramatically increases at this level.
What is the normal pressure in the main pulmonary artery? Is the pulmonary system high or low resistance?
15 mmHg
Low
Why is it unsafe for patients with pulmonary hypertension to fly / move to a higher altitude?
On planes / at higher altitudes, the FiO2 is lower. As a result, the pulmonary vessels vasoconstrict (hypoxic pulmonary vasoconstriction), raising the resistance and workload on the right heart, potentiating signs of PH.
What is vital capacity? What is the volume following this?
It is the volume of air moved from a maximum inhale to a maximum exhale.
The remaining volume is called residual volume.
What lung volumes cannot be measured via spirometry?
Total lung capacity
Functional residual capacity
Residual volume
(It all boils down to residual volume - to know total lung capacity and FRC, you would have to know residual volume)
What radiation therapy technique is used to provide a highly conformative RT dose in an effort to spare normal tissues?
In what tumor type (anatomic) is this very helpful in?
Intensity modulated radiation therapy (IMRT)
Sinonasal tumors (allows avoidance of the eyes and brain)
What is the main determinant regarding the risk of late term RT side effects? What broad group of protocols has a higher risk?
The dose of radiation delivered per fraction (higher dose = more risk)
Stereotactic protocols
Most common sinonasal tumor in dogs, cats?
Dogs - carcinoma (ACA, SCC)
Cats - lymphoma
The real term for ‘lung digit syndrome’
Acrometastasis
Aside from the lungs themselves, what are two common sites that pulmonary tumors can metastasize to?
Brain and bone
A cause of lameness in dogs with either primary or metastatic pulmonary neoplasia:
Hypertrophic osteopathy (HO)
What is the width of an intra-pulmonary structure able to be detected on thoracic CT v thoracic radiography?
1 mm (CT) v 7-9 mm (rads)
What type of cells secrete surfactant?
Type 2 alveolar cells
What is p53 and what do increased amounts of staining for this mean?
p53 is a tumor suppressor gene. Mutations in this gene can allow for the formation of cancers. When this gene is mutated, the protein it produces is no longer broken down well and will remain in tissues, and can be stained for.
What does mTOR stand for? What is this molecule?
Mammalian target of rapamycin
This is a protein kinase that is often up-regulated in cancer pathways.
How does one distinguish OSAs from other tumors of bone on a histological basis?
The presence of osteoid produced by the neoplastic cells (will only be present with OSA, not other primary bone tumors)
What percent of dogs with OSA will have metastasis at the time of diagnosis? At euthanasia?
15%, 90%
What is the mechanism of action of bisphosphanates?
These cause apoptosis / inhibition of osteoclasts, and therefore reduce bony lysis.
Along what portion of the bone do metastases most frequently occur and why?
Diaphysis; proximity to the nutrient foramen.
Multiple cartilaginous exostoses occur secondary to derangement in this process.
Endochondral ossification
What percentage of dogs with PDH will develop neurologic signs secondary to their tumor?
15-25%
What is the MOA for trilostane?
Inhibition of the 3-beta-hydroxysteroid dehydrogenase enzyme
What is a common and unique sign of feline hyperadrenocorticism?
Thin, fragile skin
What clinical sign in a patient that has insulin resistant DM should increase suspicion for hypersomatotropism?
Weight gain
What percent of cats with DM likely have hypersomatotropism? What percent with insulin-resistant DM?
10-15%
30%
What is the most common adrenocortical disorder in cats?
What are two main consequences of this disease?
Primary hyperaldosteronism
Hypokalemia (and resultant muscle weakness) and hypertension.
Which commonly used diuretic is an aldosterone antagonist? Why is this different from furosemide?
Spironolactone
Potassium sparing
What is the most common location for a chromaffin cell tumor? What are two other names for these tumors outside their most common location?
- Adrenal medulla (pheochromocytoma)
- paraganglioma or extra-adrenal pheochromocytoma
What is the best way to distinguish between pheochromocytoma and other types of adrenal tumors?
Measurement of plasma or urinary normetanephrines
What are three indications that an incidentally identified adrenal mass should be surgically removed?
- Size - greater than 2.5 cm
- Functional
- Locally invasive
Small, inactive tumors can be monitored serially with AUS q3 months.
What is the best way to work up a suspected thyroid tumor? What test should absolutely be avoided?
- cervical CT
- biopsy
Most common endocrine disorder in cats
Hyperthyroidism
What percentage of hyperthyroid cats have a total T4 within normal limits?
10%
What is the treatment of choice for feline hyperthyroidism?
Radioactive iodine therapy
Proliferation of this cell type results in primary hyperparathyroidism?
Chief cells