UWorld Practice Questions #3 Flashcards
Lesions to the macula (i.e. drusen deposition in condition of macular degeneration) will produce what?
Central scotomata which is visual field defect to the center of vision, surrounded by areas of normal vision. This is b/c the macula does the center of our vision and has the highest level of acuity.
How does Kawasaki disease present and what is a serious complication of it?
Presents w/ fever of 5+ days plus: bilateral non-exudative conjunctivitis, cervical lymphadenopathy, mucositis (fissured lips, strawberry tongue), edema of hands and feet, erythema of palms and soles, and rash.
A serious complication is coronary artery aneurysm.
What type of media is Thayer-Martin media?
Selective media –> antibiotics kill potential contiminants
What characterized erectile disorder?
Persistent inability to attain or sustain an erection.
The deep inguinal ring is a physiologic opening in the _____, and the superficial inguinal ring is a physiologic opening in the _______?
Deep inguinal ring –> transversalis fascia
Superficial inguinal ring –> external oblique muscle apopneurosis.
What sort of drugs are aprepitant and fosaprepitant? What are they used for?
They are neurokinin-1 (NK1) receptor antagonists. NK1 is one of the receptors involved in the vomiting reflex so these meds can be used for acute and delayed vomiting induced by chemotherapy, that is refractory to more traditional chem anti-emetic tx like ondansetron and metoclopramide.
What is allocation bias?
Bias in a study that results from non-random allocation into the different study groups. For example, physicians may enroll sicker patients into the experimental arm of a study - this would be allocation bias.
Note that this is DIFFERENT from selection bias where the issues is the study population does not represent the intended population.
What is detection bias?
Where a risk factor for something results in more extensive workup and thus a greater likelihood of finding something. Example –> smoking pts undergoing more imaging so cancer is detected more often.
What is the presentation of norepinephrine extravasation and how do you treat it?
Blanching of a vein into which norepi is being infused plus induration, pallor, hardness and coolness to the surrounding area is a sign of this condition (where norepi is leaking causing vasoconstriction and potentially tissue necrosis)
Tx = local injection of an alpha blocker like phentolamine.
How does the drug clomiphene work?
It is a selective estrogen receptor modulator that prevents the negative feedback of estrogen on the hypothalamus and pituitary by circulating estrogen. This results in increased LH and FSH production and ovulation.
In Friedrich-Ataxia, where does neural degeneration occur?
In the spinocerebellar tracts, lateral corticospinal tracts, dorsal columns and dorsal root ganglia.
How does gestational choriocarcinoma present? How does it appear histologically?
Presents w/ vaginal bleeding, uterine enlargement and an abnormally elevated BHcg. Also, can get hemoptysis as it is a rapidly aggressive tumor whose most common met site is the lung.
Histo shows abnormal proliferations of cytotrophoblasts and sycytiotrophoblasts. No villi are present.
In an orbital floor injury (i.e. from getting socked in the face while getting molly-whapped in a bar fight) allows the contents of the orbit to herniate into what area?
The maxillary sinus.
What is the most important prognostic factor for post-streptococcal glomerulonephritis?
Increased age. Only 60% of adults fully recover while the rest develop stuff like persistent HTN, rapidly progressive GN, recurrent proteinuria and chronic renal insufficiency.
Describe the most common pathogenesis to infective endocarditis?
First is disruption of the normal endocardial surface, which occurs most commonly via turbulent blood flow leading to focal adherence of fibrin and platelets. This forms a sterile fibrin-platelet nidus to which bacteria can then bind and colonize.
Note that S. aureus is unique in that it can adhere to normal or damaged endothelial cells.
What does the Nissl substance in neurons represent?
The rough endoplasmic reticulum.
Histologically, what characterizes acute neuronal injury (ultimately leading to cell death)?
Shrinkage of the cell body, pyknosis (irreversible condensation of chromatin) of the nucleus, loss of nissl substance and an eosinophilic cytoplasm.
Histologically, what characterizes an axonal reaction (where a neuron’s axon is severed)?
Cell body enlargement, nucleus moves to the periphery, enlargement of the nucleuolus, and dispersion of the Nissl substance.
What makes up the calcifications seen on imaging in craniopharyngiomas?
Cholesterol crystals. Why on macroscopic exam they can be cystic w/ a high cholesterol content.
Micrognanthia, prominent occipt, clenched hands w/ overlapping fingers and low set ears in a newborn is most likely indicative of what trisomy?
Trisomy 18 (Edward syndrome)
What neonatal condition does a 5p deletion cause?
Cri-du-chat syndrome. Pts have cat-like cry as well as hypotonia, failure to thrive and developmental delay.
What are degmacytes?
Bite cells
Compared to hexokinase, glucokinase (which is present in hepatocytes and B cells) has a ____ Km and ______ Vmax
Higher Km (meaning less affinity for glucose) and higher Vmax
What are the essential amino acids? List them including whether they are glucogenic, ketogenic or both.
Glucogenic: methionine, valine, and histidine (his is only essential during periods of growth as body can’t make enough then)
Ketogenic: isoleucine, phenylalanine, threonine and tryptophan
Glucogenic/ketogenic: leucine and lysine
*Note that arginine is like histidine in that it is essential during periods of growth.
What is the treatment for methemoglobinemia?
Methylene blue. It is has been shown to help w/ the conversion of iron back into ferrous (2+) form.
What are some drugs that can cause methemoglobinemia?
Oxidizing agents like dapsone, sulfonamides, and local anesthetics like benzocaine
What is thiosulfate used to treat?
Cyanide poisoning.
What is the thyroid’s embryological origin?
Thyroid diverticulum arises from the floor of the primitive pharynx.
What are perioxisomes involved in the metabolism of?
Very long chain fatty acids, branched chain fatty acids, amino acids, and ethanol.
What is the most common form in which mutations that produce Duchenne muscular dystrophy occur?
Frameshift mutation
What do Ca, P and alk phos labs show in osteoporosis? How about Paget’s disease?
Osteoporosis –> normal Ca, normal P, and normal or decreased alk phos
Paget’s disease –> normal Ca and normal P w/ elevated alk phos.
Why can acute ethanol intoxication lead to lactic acidosis and hypoglycemia?
Booze leads to increased NADH:NAD+ ratio (b/c of the oxidation of metabolizing alcohol). This ratio shunts pyruvate to lactate formation and this both creates the acidosis (lactic acidosis) and causes hypoglycemia as there is not enough pyruvate available to do gluconeogenesis.
Which atypical antipsychotic is most strongly associated w/ galactorrhea as a side effect?
Risperidone
Which malignancies are most likely to metastasize to the bone?
Prostate/Breast > Kidney/Thyroid/Testes/Lung
What are “slow waves” in the GI tract?
They are rhythmic depolarizations and repolarizations of the smooth muscles cells within the muscularis propria of the stomach and intestines. Slow waves determine the frequency of contractions of the gastrointestinal tract.
What is an adverse effect from fluoroquinolones to know about and who is at increased risk?
Tendinitis. Increased risk = old, renal disease (transplant, hemodialysis, etc), and long term glucocorticoid use.
What is the first line treatment for diabetic gastroparesis?
Metoclopromide
What is rheumatoid factor?
It is antibody (typically IgM) against the Fc component of IgG.
What do anti-phospholipid antibodies (found in SLE and antiphospholipid antibody syndrome) cause?
A hypercoagulable state w/ paradoxically increased PTT.
What are the characteristics of CREST syndrome?
Calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia.
What is the most common mutation causing idiopathic pulmonary arterial hypertension (PAH) and what does this cause?
BMPR2 gene which predisposes pts to dysfunctional endothelium and smooth muscle proliferation. A second insult leads to vascular remodeling, increased resistance, and ultimately leads to PAH.
What are the most common pathogens that pts w/ CGD are susceptible to?
Catalase + ones, most common being S. aureus, Burkholderia cepacia, Serratia marcescens, Norcardia and Aspergillus.
Which virus is associated w/ fulminant hepatitis in pregnant women? How would you characterize it?
Hepatitis E virus. It is a naked ssRNA viral spread via fecal oral route.
What shape are cysteine renal stones?
Hexagonal. They are radio opaque.
What is the microscopic shape of magnesium ammonium phosphate stones (aka struvite stones)?
They are prism shaped and can be described as coffin lid shaped. They are radio opaque.
What kind of drug is canagliflozin?
SGLT2 inhibitor.
What is the pathogenesis, presentation and dx of Hartnup disease?
It is a genetic defect in the neutral amino acid transporter such that pts get impaired transport of neutral amino acids in the intestine and proximal renal tubule. Tryptophan is a neutral amino acid and a precursor for niacin and so this disorder causes niacin deficiency and basically has a pellagra-like presentation (including cerebellar ataxia in childhood).
Dx is by presence of excessive amounts of neutral amino acids in the urine.
What is the most common cause of thoracic outlet syndrome?
Compression of the lower trunk of the brachial plexus in the scalene triangle, btwn the anterior and middle scalene muscles
What is diphenoxylate?
An opioid anti-diarrheal.
Meconium ileus is a very specific finding for what disease?
CF
What enzyme is deficient in patients with xeroderma pigmentosum?
UV specific endonuclease. As such they cannot repair the thymidine dimers caused by UV exposure and get photosensitivity, hyperpigmentation and can even get skin cancers.
What histologic changes characterize minimal change disease?
Normal light and immunofluorescence microscopy. Effacement of foot processes can be seen on electron microscopy.
What causes the selective albuminuria in minimal change disease?
Loss of the negative charge at the glomerular basement membrane that allows positively charged albumin to escape.
Crescent formation is most typically associated w/ which glomerular disease?
Rapidly progressive glomerulonephritis
What histologic changes characterize diabetic nephropathy?
Mesangial expansion and glomerular basement membrane thickening. Kimmelstiel-Wilson lesions are specific for this and they are ovoid or spherical hyaline (eosinophilic) masses found in the mesangium.
What brain lobe does the Meyer’s loop travel in? As such, what visual defect does damage produce?
Travels in the temporal lobe so damage produces the “pie in the sky” defect.
What sort of receptor is the glucagon receptor?
Gs GPCR
Why is PaO2 normal in carbon monoxide poisoning?
Because PaO2 is a reflection of the amount of O2 dissolved in the blood and this is unchanged by CO. Instead, CO is changing the oxygen carrying capacity of Hgb in the blood, and is L shifting the Hgb-O2 dissociation curve.
What is the main measure of association reported in case-control studies? How is it calculated?
Odds ratio. Incidence measures like relative risk cannot be calculated b/c by definition patients already have the disease.
OR = odds of exposure in cases / odds of exposure in controls
Describe the pathogenesis of a lacunar infarct?
These occur in the small penetrating arterioles of deep brain structures. Chronic HTN promotes lipohyalinosis, microatheroma and hardening/thickening of vessels walls leading to formation which narrows vessels and predisposes to thrombotic infarct. After several weeks the necrotic spaces turn into fluid filled cavities called lacunae.
Intra-operative rupture of hydatid cysts (caused by echinococcus) can be lethal how?
Spilling of cyst contents can lead to anaphylactic shock.
What makes up the 3’ end of tRNA?
CCA
In duodenal ulcers secondary to H. pylori, where is the GI tract does the bug preferentially colonize?
The gastric antrum. Note that in gastric ulcers, it is associated w/ colonization of the gastric body.
In ischemic acute tubular necrosis (ATN), what parts of the nephron are most vulnerable to ischemic injury?
The proximal tubule and thick ascending limb of the loop of Henle.
What is CEA elevated in and what can it be used for?
Carcinoembryonic antigen (CEA) is elevated in breast, gastric and pancreatic malignancies (as well as some benign diseases like IBD). It can be used as a sensitive marker for cancer residual disease after surgery and colorectal cancer recurrence.
What are 2 classic manifestations of pineal gland tumor? Why?
1 = obstructive hydrocephalus (headache, papilledema, vomiting) due to aqueductal stenosis
2 = Parinaud syndrome due to compression of the pretectal region of the midbrain. This presents w/ limitation of upward gaze, bilateral lid retraction, and pupils that react to accommodation but not light.
Why can ACEIs and ARBs cause oligohydramnios when used during pregnancy?
Because angII is necessary for renal development.
It is very important to screen all patients with major depressive for what?
A past hx of mania so that the distinction can be made between MDD and bipolar disorder. This is really important in order to ensure that pts get the correct tx.
Antidepressant monotherapy should be avoided in patients with bipolar as this can precipitate mania (tx emergent mania).
Wilson disease is associated w/ cystic degeneration of what brain area?
The putamen
Calmodulin is important for excitation-contraction coupling in which cells?
Smooth muscle cells as they lack troponin.
What do neurophysins do?
They act as carrier proteins for oxytocin and ADH from the paraventricular and supraoptic hypothalamic nuclei respectively, to the posterior pituitary.
In inferior colliculi and medial geniculate bodies are part of?
The auditory pathway
In idiopathic intracranial HTN (most commonly seen in young, obese women), when do sxs characteristically worsen?
During valsalva so doing stuff like bending over, lifting objects, coughing, etc.
Describe the pathophysiology of optic disc edema in increased intracranial pressure:
Increased ICP is transmitted thru CSF to subarachnoid space which is continuous w/ the optic nerve sheath. This pressure build-up compresses the optic nerves externally and this impairs axoplasmic flow which results in the papilledema.
Choroidal inflammation of the eye is characteristic of?
Posterior uveitis.
What is the most significant risk factor for UTI while a pt has a catheter?
Duration of catheterization
Where does Parvovirus replicate?
In erythrocyte precursors in the bone marrow
What is the mechanism of action of adenosine?
It causes hyperpolarization of AV nodal cells, briefly blocking conduction thru the AV node.
What is the most common location for osteonecrosis (avascular necrosis) and what are common predisposing conditions?
Femoral head = most common location. Predisposing conditions include sickle cell disease, glucocorticoid use, alcoholism and vasculitis.
What is the use and mechanism of action of azathioprine? What is its interaction w/ allopurinol?
It is the prodrug of 6-mercaptopurine and the active form works by inhibiting de novo purine synthesis –> suppresses the immune system by blocking lymphocyte proliferation due to blocked nucleotide synthesis.
Xanthine oxidase is one of the metabolism pathways by which azathioprine is degraded so by blocking XO w/ allopurinol there is more drug that is converted into the active for.
How does tacrolimus work and what is it used for?
It is an immune suppressant. Works by inhibiting calcineurin and blocking T cell activation by preventing IL-2 transcription.
What is the mechanism of action of rifamixin in treating hepatic encephalopathy?
It is a non-absorbable antibiotic that alters GI flora to decrease the intestinal production and absorption of ammonia.
*note that a primary source of ammonia is intestinal breakdown of nitrogenous products by bacteria.
What does the ristocetin aggregation test measure?
In vitro vWF dependent platelet aggregation.
Bernard-Soulier syndrome is hereditary deficiency of what?
GP Ib receptors
Glanzmann thrombocytopenia is hereditary deficiency of what?
GP IIb-IIIa receptors
How does C. diphtheriae acquire its virulence that causes pseudomembranous pharyngitis?
Through bacteriophage-mediated infection with the Tox gene, which codes for the diphtheria AB exotoxin.
What is spongiosis? Name a dermatological condition that demonstrates it?
Spongiousis is an accumulation of edema fluid in the intercellular spaces of the epidermis. It is seen in acute allergic contact dermatitis.
CD15+ and CD30+ is characteristic staining for…
Reed-Sternberg cells in Hodgkin’s lymphoma.
Isolated cleft palate occurs due to failure of…?
Fusion of the lateral palatine processes, the median palatine processes, and/or the nasal septum
What does alpha-amantin (a toxin found in mushroom caps) inhibit?
RNA polymerase II
What cells produce intrinsic factor?
Gastric parietal cells
What is the pathogenesis of I-cell disease? How does it present?
Pathogenesis = failure to add mannose-6-P residues to proteins that should be directed to the lysosome.
Presentation = course facial features, developmental delay, clouded corneas, restricted joint movement and elevated lysosomal enzymes.
What is a Michaelis-Menten constant?
Same thing as Km. It is the concentration of substrate at which a reaction operates at 1/2 Vmax. Thus, it is a reflection of an enzyme’s affinity for substrate.
Is it bullous pemphigoid or pemphigus vulgaris that has a + Nikolsky sign?
Pemphigus vulgaris. This means the blisters/bullae rupture easily.
______ has the finding of morula w/in the cytoplasm of granulocytes while _______ has the finding of morula w/in the cytoplasm of monocytes?
Granulocytes –> anaplasmosis
Monocytes –> erlichiosis
Which type of electromagnetic radiation is thought to be the major contributor to melanoma?
UVB rays.
What is the equation for total peripheral resistance for a parallel circuit?
1/Rt = 1/R1 + 1/R2 + 1/R3 etc.
What is unique about the L type Ca++ channels in skeletal muscle as compared to smooth muscle or cardiac muscle?
They interact directly with the ryanodine receptor –> mechanical coupling.
What kind of drug is chlorpheniramine?
It is a first generation anti-histamine
How is a dx of tetanus made?
Clinically, by hx and PE.
