UWorld Practice Questions #4 Flashcards
How is the filtration fraction (GFR/RPF) affected by a decrease in renal perfusion pressure? Why?
The filtration fraction will increase. This is because GFR autoregulation causes the afferent arteriole to dilate and efferent arteriole to constrict in response to decreased perfusion pressure. This means that GFR is maintained at the expense of decreased RPF so the fraction increases.
Note that glomerular capillary oncotic pressure rises in response to increased filtration fraction –> more stuff filtered so there is a higher concentration of protein left in the capillary.
What does stimulation of D1 receptors do?
Causes relaxation of vascular smooth muscle.
What is acitretin and what is it used for?
It is in the retinoid family (like isotretinoin used for acne) and is the preferred drug in this class to treat psoriasis.
What is xerosis? How do you treat it?
Xerosis is a dry, itchy rash with cracked skin. It is most commonly seen in elderly pt in the winter months, as heaters reduce air humidity and promote dry skin.
Tx = focus on maintaining the barrier and replenishing skin water losses –> lukewarm instead of hot baths, neutral or acidic cleansers as opposed to alkaline soaps, and moisturizing immediately after bathing.
What are the positively charged amino acids at physiological pH?
Histidine, lysine and arginine
What are the negatively charged amino acids at physiological pH?
Glutamate and aspartate
What are the non-polar amino acids?
Alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline and glycine.
What is the mechanism of action of probenecid? As such, how can it be used?
It inhibits organic acid transporters in the kidney. By inhibiting the transporter that reabsorbs uric acid it can be used to tx gout. Additionally, by inhibiting the organic acid transporter thru which antibiotics like pencillin is secreted into the lumen, it can be used to raise levels of abx (by preventing its secretion at the kidneys).
What is the pathophysiology of cough syncope? In what population does it typically occur?
In cough syncope, during a coughing fit there is increased intrathoracic pressure such that venous return to the heart is decreased and this reduces CO and cerebral blood flow leading to syncope.
This most commonly occurs in male COPD pts who are overweight.
Xeroderma pigmentosum is a failure of what process?
Failure of the nucleotide excision repair process.
What causes Bloom syndrome and how does it present?
Defect in DNA helicase RecQL3 gene. Presents with photosensitivity, short stature, erythema and telangiectasias. Pts are predisposed to GI and lymphoproliferative disorders.
Bcl-2 overexpression is characteristic of what malignancy?
Follicular lymphoma
C-Myc overexpression is characteristic of what malignancy?
Burkitt lymphoma
What causes spider angiomata in patients with cirrhosis?
It is the hyperestrogenemia of cirrhosis that causes them.
What are the manifestations of hyperestrogenemia in liver failure?
Spider angioma, palmar erythema, gynecomastia, testicular atrophy and decreased body hair.
Histologically, what do neurofibromas consist of?
Loose, disorganized proliferations of Schwann cells, fibroblasts, and neurites.
What are Merkel cells?
They are the neuroendocrine receptor cells in the skin associated with a sense of touch.
For which malignancy does endometriosis increase risk?
Ovarian epithelial cancer. NOT endometrial cancer.
What is the purpose of using drug-eluting coronary stents (i.e. ones covered in mTOR inhibitors like everolimus)?
To prevent intimal hyperplasia that would lead to re-stenosis.
In a distal clavicle fracture, what muscle(s) pull the distal segment inferior-laterally? What muscle(s) pull the proximal segment medially and superiorly?
Inferior and lateral –> Deltoid
Medial and superior –> SCM and trapezius
*This displaces the fracture and increases the risk of non-union.
How do patients with ornithine transcarbamylase deficiency present? What is the inheritance pattern?
Newborns present shortly after birth w/ poor feeding and vomiting. They have normal blood glucose, hypotonia, hyperammonemia and increased urinary orotic acid. Pts can lethargy/coma, cerebral edema and seizures from the accumulation of ammonia.
X-linked inheritance pattern.
What is most commonly seen in uncle herniation of the brain?
CN3 palsy and contralateral hemiparesis due to compression of the ipsalateral cerebral peduncle by the herniated temporal lobe.
What are early signs of hypokalemia?
Weakness, muscle cramps, myalgias and fatigue
Describe the pathogenesis of osteoarthritis?
It is an interplay between inflammatory and non-inflammatory processes that cause deterioration of the joint cartilage. Repeated biomechanical stress seems to be of etiologic importance (as evidenced by increased incidence of this in obese people).
What is enfurvitide?
It is a fusion antagonist used to tx HIV
What are dolutegravir and raltegravir?
Integrase inhibitors used to tx HIV
Name the most common manifestations of VHL syndrome?
Cerebellar and retinal hemangioblastomas, renal cell carcinoma and pheochromocytoma
Decribe HbC?
It is a hemoglobin variant where the hemoglobin forms hexagonal crystals. Pts get mild anemia but are usually asymptomatic and the oxygen binding properties are not that different from adult hemoglobin.
Where are Kayser-Fleischer rings found in Wilson disease?
These are fine granular copper deposits in the cornea.
Where are Lisch nodules found? In what condition?
Lisch nodules are located in the iris and are found in NF-1
What does aldehyde dehydrogenase deficiency lead to?
The classic alcohol flush reaction. (As such, I think this is the enzyme that antabuse inhibits).
What is a galactocele?
A milk-filled cyst due to an obstructed breast duct.
What mutation is dysplastic nevus syndrome (resulting is significantly increased lifetime risk of melanoma) associated with?
CDKN2A which is on chromosome 9p21.
What are the histopathological characteristics of a dysplastic nevus?
Nests of nevomelanocytes w/ angulated, hyperchromatic nuclei and bridging w/ nests in neighboring rete pegs
What sort of nevi are papular (raised) and what sort of nevi are flat (macular)
Papular –> intradermal
Macular –> junctional
Which GABA channel acting drugs does flumazenil NOT affect?
Does not affect barbiturates
What does the prosencephalon give rise to?
Telencephalon –> cerebral hemispheres and lateral ventricles
Diencephalon –> thalamus and third ventricle
What does the mesencephalon give rise to?
Midbrain and cerebral aqueduct
What does the rhombencephalon give rise to?
Metencephalon –> pons, cerebellum, and upper 4th ventricle
Myelencephalon –> medulla and lower 4th ventricle
Where does de novo purine and pyrimidine synthesis occur?
In the cytosol.
How does p57 staining vary btwn compete and partial moles?
Complete stain negative. Partial stain positive.
What is the mechanism of retinoids in treating acne?
They act to decrease sebum production and normalize keratinocyte differentiation. They also increase cell turnover and shedding of cells from the stratum corneum which reduces hyperkeratinization, opens blocked pores and prevents the formation of microcomedones.
Where is the esophageal hiatus and what passes thru it?
It is located in between fibers of the right crus of the diaphragm. The esophagus and the vagal branches pass through it.
What passes thru the aortic hiatus in the diaphragm?
The aorta, the thoracic duct, and the azygos vein.
What sort of drug is amlodipine?
It is a dihydropyradine CCB. Note that this class selectively vasodilates arterioles in order to decrease BP (decreasing afterload which decreased myocardial O2 demand).
What is one way to distinguish between glucose-6-phosphatase deficiency (Von Gierke disease) and debranching enzyme deficiency (Cori disease)?
In Cori disease the pt’s hypoglycemia resolves w/ admin of fructose whereas w/ Von Gierke it does not as these pts can’t convert fructose or galactose to glucose.
How does pontine hemorrhage present?
Pinpoint pupils, loss of horizontal gaze, quadraparesis, deceberate posturing and rapidly evolving coma that rapidly progresses to death.
What are the most common areas affected by non-traumatic intracranial hemorrhage (seen in the setting of HTN)?
Basal ganglia, lobar regions, thalamus, pons and cerebellum.
Putamen and thalamus are most common.
What are the mechanisms by which intracranial neoplasms lead to increased ICP?
Can obstruct CSF flow and cause a non-communicating hydrocephalus. Can disrupt the blood-brain-barrier that leads to increased vascular permeability and plasma filtration into the brain parenchyma, resulting in vasogenic edema.
Describe cytotoxic edema of the brain and what typically causes it?
Cytotoxic edema is an increase in intracellular fluid w/in neurons, endothelial cells and glial cells as a result of injury that damages the functioning of the Na/K ATPase. It usually occurs following ischemic injury to the brain.
Where does the tetany of tetanus infection classically first present?
In the jaw producing lockjaw
What is the timeframe for when papillary muscle rupture occurs post-MI?
Typically 3-5 days after. Same timeframe as inter-ventricular septum rupture/defect
What is PECAM-1 involved in?
The transmigration step of neutrophil recruitment.
What enzyme is defective in hereditary orotic aciduria and how does it present?
Enzyme defect of UMP synthase (in the de novo pyrimidine synthesis pathway). Why uridine supplementation can bypass this defect and improve sxs.
Presents w/ physical and mental retardation, megaloblastic anemia, and elevated urinary orotic acid levels.
What are important parameters to look at in distinguishing a cause of metabolic alkalosis?
Want to look at pt’s volume status, and the urine Cl.
Urine Cl will be low (<10) in conditions like vomiting and NG suctioning. Urine Cl will be high (>20) in conditions like diuretic use and mineralocorticoid excess states (i.e. Conn syndrome)
Which common metabolic alkalosis presentations are saline responsive and which are not?
Saline responsive –> vomiting, diuretics
Saline unresponsive –> mineralocorticoid excess
Why do patients w/ C1 inhibitor deficiency (presenting w/ facial swelling, angioedema and GI manifestations) have high levels of bradykinin?
Because in addition to preventing C1 mediated cleavage of C2 and C4, C1INH also inhibits the conversion of kininogen to bradykinin.
What causes type 4 renal acidosis?
Either hyperaldosteronism or aldosterone resistance.
How are the following agents antiseptic: alcohol? clorhexadine? iodine?
Alcohol –> disruption of cell membranes and protein denaturization
Chlorhexadine –> disruption of cell membranes and coagulation of cytoplasm
Iodine –> Halogenation of proteins and nucleic acids. ***Note that of the three, only this one is sporicidal (as is hydrogen peroxide)
What anastamosis is created to supply blood to a donated kidney in renal transplant?
Donated renal artery is connected to recipient external iliac artery.
Why can prolactinomas cause amenorrhea?
Elevated prolactin suppresses GnRH production.
What is milrinone and what is it used for?
It is a selective phosphodiesterase (PDE3) inhibitor. Prevents cAMP degradation in cardiac and smooth muscle leading to positive inotropic and vasodiliatory effects respectively. It can be used in HF.
What are the first generation anti-histamines? Second generation ones?
First gen –> hydroxyzine, promethazine, diphenhydramine, and chlorpheniramine
Second gen –> loratadine and ceterizine
What do homeobox genes do? What is a homeobox?
They typically code for transcription factors that alter expression of genes involved in the segmental organization of the embryo.
A homeobox is a conserved sequence of DNA, usually about 180 bases long. Homeobox genes have them.
What is an anal fissure? How do they normally occur? And how do they present?
Anal fissure = longitudinal tearing of the anal mucosa dital to the dentate line, most commonly in the posterior midline location.
Usually due to passage of hard stools and constipation leading to increased anal pressures and stretching of the mucosa.
Present w/ sharp pain and bright red rectal bleeding on defecation.
Chronic lymphedema is a RF for what?
Cutaneous angiosarcoma
Where is hepcidin made?
Liver parenchymal cells
What is the mechanism of action of vigabatrin? What is it used for?
It is an irreversible inhibitor of GABA transaminase (thus preventing GABA catabolism in the CNS). It can be used for tx resistant epilepsy.
When is pulmonary vascular resistance (PVR) at the lowest?
Near the FRC on respiration/PFT curves. At very high or low lung volumes, resistance is increased.
In what female neoplasm are Schiller-duval bodies seen?
In yolk sac tumors.
What does damage to the frontal eye field cause?
Causes the eyes to deviate to the ipsalateral side?
What are the physiological effects of dopamine at different drug levels?
At low doses it stimulates D1 receptors. At the kidney this leads to increased renal perfusion, increased GFR and increased salt excretion. At higher doses it stimulates B1 (increases cardiac contractility) and a1 (vasoconstriction increasing systemic vascular resistance) receptors.
Overall, in terms of receptor binding it is D1 > B1 > a1
Describe amyloid angiopathy and how it presents?
Amyloid angiopathy is where you have B-amyloid deposition in the walls of medium to large sized cerebral vessels. It weakens them are predisposes to rupture.
It presents w/ recurrent brain hemorrhage, often involving the parietal and occipital lobes. It is the most common cause of lobar hemorrhage, and commonly occurs in the elderly.
What is another name for folinic acid?
Leucorvin
What is the mechanism of amifostine and what is it used for?
It is a cytoprotective free radical scavenger that is used to decrease the nephrotoxicity associated with platinum containing and alkylating chemo. It is also used to decrease dry mouth.
What is filgastrim?
A granulocyte colony stimulating factor analog
What kind of vaccine is the rabies vaccine for humans?
A killed virus vaccine
What is the inheritance of von Willebrand disease?
Autosomal dominant
What is the effect of endogenous vasopressin acting on the V1 receptor?
Causes vascular smooth muscle contraction
What is the pathogenesis of alcohol induced hepatic steatosis?
Decreased free fatty acid oxidation due to excess NADH.
Where are B5 and B7 absorbed in GI tract?
In the small and large bowel via the Na dependent multivitamin transporter.
Where is B6 absorbed?
Jejunum and ileum
What are protective factors for ovarian epithelial neoplasm?
multiparity, combined oral contraceptives, and breastfeeding
What sorts of fibers does the posterior limb of the internal capsule carry? How about the anterior limb?
Posterior –> corticospinal motor and somatic sensory, visual and auditory fibers.
Anterior –> Portion of the thalamicocortical fibers.
What are the opioid side effects to which tolerance does not rapidly develop?
Constipation and miosis
Which gyrus of the occipital lobe receives upper field information? How about lower field info?
Upper field –> lingual gyrus of striate cortex
Lower field –> cuneus gyrus of striate cortex
Block of which adrenergic receptor causes bronchospasm and wheezing?
B2
What is the pathogenesis of increased lipoprotein synthesis by the liver in nephrotic syndromes?
There is all this protein loss and so intravascular oncotic pressure decreases and this causes the liver to increase lipoprotein synthesis leading to hyperlipidemia.
In blood, CO2 is transported as H2CO3 which dissociates. How is the H+ transported?
While the HCO3- mainly leaves the RBC in exchange for Cl- entering, the H+ generally stays in the RBC and is attached to Hgb by being buffered by histidine residues on the side chains of alpha and beta globin molecules.
What is the Haldane effect?
In the lungs, the binding of O2 to hemoglobin drives release of CO2 and H+ from hemoglobin.
What are possible complications of varicose veins?
This can lead to venous insufficiency producing stasis derm and skin ulceration.
Describe Peau d’orange. What does it indicate?
It is an erythematous, itchy breast skin rash w/ skin texture changes similar to an orange peel. It is the key dermatological presentation of inflammatory breast cancer and is caused by cancerous cells obstructing lymph drainage.
How does T3 affect bone?
It increases bone turnover by osteoclasts.
What characterizes Rett syndrome? What is its inheritance pattern?
X-linked dominant disorder (affected males die in utero) characterized by progression neurodegeneration and stereotypical hand movements.
What is tryptase and when it is seen?
It is an enzyme that is relatively specific to mast cells (released along w/ histamine at degranulation) and elevated levels are seen in anaphylaxis.
What is 5-hydroxyindoleacetic acid? When is it used clinically?
A breakdown product of serotonin. High levels are used to screen for carcinoid syndrome.
Hyperactivity of the ________ pathway is associated w/ the positive sxs of schizophrenia, whereas underactivity of the ______ pathway is associated w/ the negative sxs?
Postive –> mesolimbic
Negative –> mesocortical
Stimulation of what nerve has been shown to be helpful for OSA?
Stim of the hypoglossal nerve. –> this increases the diameter of the oropharynx airway and reduces the freq of apneic events.
What muscles do Kegel exercises seek to strenthen in improving stress incontinence?
The levator ani muscles.
Where does lymph of the testes drain? How about the scrotum?
Testes –> para-aortic LNs
Scrotum –> superficial inguinal LNs
