Uworld Flashcards
What is the MOA of organophosphates?
Organophosphates are cholinesterase inhibitors that inhibit the breakdown of acetylcholine, leading to a state of cholinergic excess.
What are the symptoms of organophosphate poisoning?
Symptoms of organophosphate poisoning include salivation, lacrimation, diaphoresis, bradycardia, and bronchospasm.
Abnormal bleeding in patients with uremia is due to what?
Abnormal bleeding in patients with uremia is due to a qualitative platelet disorder that causes prolonged bleeding time with normal platelet count, prothrombin time, and activated partial thromboplastin time.
When does maturing erythrocytes lose their ability to synthesize heme?
Maturing erythrocytes lose their ability to synthesize heme when they lose their mitochondria, which are necessary for the first and final 3 steps of heme synthesis.
Postural skeletal muscles such as the soleus and paraspinal muscles contain what kind of muscle fibers?
Postural skeletal muscles such as the soleus and paraspinal muscles contain predominantly Type I, slow twitch muscle fibers that derive ATP primarily via oxidative (aerobic) metabolism.
The hamstrings are composed of which muscles?
The hamstrings are composed of the biceps femoris (long and short heads), semitendinosus, and semimembranosus.
Hamstring injury can result in what?
Hamstring injury can result in painful, limited hip extension and knee flexion and ischial avulsion fractures can occur at origin sites.
What is the treatment for herpes simplex virus encephalitis?
The treatment for herpes simplex virus encephalitis is intravenous acyclovir.
What is the MOA of acyclovir?
Acyclovir is a nucleoside analogue whose active component is incorporated into replicating viral DNA, leading to termination of viral synthesis.
Annular pancreas (ie, pancreatic tissue encircling the duodenum) is caused by what?
Annular pancreas (ie, pancreatic tissue encircling the duodenum) is caused by abnormal rotation of the ventral pancreatic bud in utero.
Annular pancreas (ie, pancreatic tissue encircling the duodenum) can cause what symptoms?
Although frequently asymptomatic, it can cause intestinal obstruction (eg, vomitting, abdominal distention), including bilious emesis if the constriction is distal to the major duodenal papilla.
In unilateral renal artery stenosis, the narrowed renal artery causes what?
The narrowed renal artery causes hypoperfusion of the affected kidney with subsequent ischemic damage (eg, tubular atrophy, interstitial ischemia, glomerular crowding).
In unilateral renal artery stenosis, the contralateral kidney shows what?
The contralateral kidney is exposed to high blood pressure and typically shows changes of hypertensive nephrosclerosis (eg, arteriolar wall thickening due to hyaline or hyperplastic arteriolosclerosis).
What is the most common cause of nephritic syndrome (eg, hematuria, edema, hypertension) in children?
Poststreptococcal glomerulonephritis. Typically occurring 2-4 weeks after a streptococcal skin infection (eg, impetigo, cellulitis)
What type of hypersensititvity reaction is poststreptococcal glomerulonephritis?
Type III (immune complex-mediated)
What antibodies are found in systemic lupus erythematosus?
Antinuclear antibodies- low specificity
Anti-ds-DNA antibodies and anti-Smith- low sensitivity but higher specificity.
Sacral spinal cord injury can lead to what?
Sacral spinal cord injury can lead to lower motor neuron injury of the S2-S4 nerve rootlets; these contribute parasympathetic innervation to the distal colon to stimulate peristalsis and voluntary motor innervation to the external anal sphincter.
Lesions in the S2-S4 nerve rootlets can lead to what symptoms?
Distal colon stool retention, fecal incontinence, and a weak external anal sphincter.
What is the treatment of Lyme disease?
Doxycycline or penicillin-type antibiotics (eg, ceftriaxone)
An acute ventilation/perfusion mismatch (eg, due to pulmonary embolism or pneumonia) causes what?
An acute ventilation/perfusion mismatch (eg, due to pulmonary embolism or pneumonia) causes hypoxemia and triggers hyperventilation.
Because the removal of CO2 is directly dependent on ventilation but the absorption of O2 is capped by the high baseline saturation of hemoglobin, the hyperventilation response typically leads to respiratory alkalosis (low arterial partial pressure of CO2) with persistent hypoxemia.
What is seen on peripheral blood smear for Babesiosis?
intraerythrocytic pleomorphic ring forms (Maltese crosses)
What is the vector for Babesiosis?
Ixodes scapularis tick
Polyarteritis nodosa is characterized by what?
Polyarteritis nodosa is characterized by segmental, transmural, necrotizing inflammation of medium sized muscular arteries.
Manifestations arise due to tissue ischemia from arterial lumen narrowing/thrombosis or bleeding from micro aneurysms.
What vessels is affected in polyarteritis nodosa?
The vessels of the kidneys, skin, peripheral nerves, and gastrointestinal tract are affected most commonly; the lung is typically spared.
What are the risk factors for abruptio placentae?
Abdominal trauma, maternal hypertension, and tobacco or cocaine use.
What is abruptio placentae and how does it present?
Abruptio placentae, detachment of the placenta from the uterus prior to fetal delivery, presents with painful vaginal bleeding; a tender, firm uterus; and fetal heart rate abnormalities.
What are the adverse effects of adenosine?
Flushing, chest burning (due to bronchospasm), hypotension, and high grade atrioventricular block
What is the MOA of adenosine?
Adenosine causes hyperpolarization of the nodal pacemaker to briefly block conduction through the atrioventricular node
What is the treatment of paroxysmal supraventricular tachycardia?
Adenosine
What can cause syncope?
Syncope results from a transient loss of cerebral perfusion, and numerous medications can cause or contribute to syncope.
Acetylcholinesterase inhibitors (eg, donepezil, rivastigmine) may cause syncope due to enhanced parasympathetic tone that leads to bradycardia and atrioventricular block with reduced cardiac output.
What is the MOA of cromolyn and nedocromil?
Cromolyn and nedocromil are mast cell-stabilizing agents that inhibit mast cell degranulation independent of the triggering stimulus.
They are less effective than inhaled glucocorticoids and are considered second-line treatment for allergic rhinitis and bronchial asthma.
What is the MOA of rivaroxaban?
Rivaroxaban is an oral anticoagulant that directly inhibits factor Xa.
It is used in venous thromboembolism and atrial fibrillation.
Small intestinal bacterial overgrowth is caused by?
Small intestinal bacterial overgrowth is caused by bacterial proliferation in the small intestine.
In normal people, intestinal peristalsis clears bacteria and reduces the reflux of colonic organisms into the small bowel; however, patients with impaired gut motility have an increased risk for bacterial overgrowth.
Uptake of glucose by skeletal muscle is mediated by what?
Uptake of glucose by skeletal muscle is mediated by glucose transporter type 4, which is translocated to the cell membrane in response to insulin and muscle contraction (via an insulin-independent mechanism).
What can cause hypoglycemia in diabetic patients?
Hypoglycemia can be precipitated by exercise in patients with insulin-treated diabetes due to the persistent effects of exogenous insulin.
Wilson’s disease can cause what to the brain?
Wilson’s disease can cause cystic degeneration of the putamen as well as damage to other basal ganglia structures.
Where is the putamen located?
Putamen is located medial to the insula and lateral to the globus pallidus on coronal sections.
What is the most common outcome in HBV-infected adults (>95%)?
The most common outcome in HBV-infected adults (>95%) is acute hepatitis with mild or subclinical symptoms that completely resolve.
Patients with von Willebrand disease often present how?
They present with a lifelong history of mucosal bleeding, including gingival bleeding, epistaxis, and/or menorrhagia.
Patients with von Willebrand disease labs show what?
These patients have normal platelet levels but typically have a prolonged bleeding time due to impaired platelet functioning.
What is the function of von Willebrand factor?
vWF functions as a promoter of platelet adhesion at sites of vascular injury by binding platelet glycoproteins to subendothelial collagen on injured blood vessel walls.
It also acts as a protective carrier protein for circulating factor VIII.
What is the mechanism behind acute organ rejection?
Acute rejection: within weeks or up to 6 months after transplant
It is predominantly cell-mediated, involving sensitization of host T lymphocytes against donor MHC antigens.
What is shown on histology for an acute organ rejection?
There is typically graft dysfunction with histology showing a dense, mononuclear (ie, lymphocytic) infiltrate.
How doe acute hepatitis A present?
Acute hepatitis A is a self-limited infection that typically presents acutely with prodromal symptoms (eg, fever, malaise, anorexia, nausea/vomiting, RUQ pain) followed by signs of cholestasis (eg, jaundice, pruritus, dark-colored urine, clay-colored stool).
What is the site of insertion for the gluteus medius muscle?
The greater trochanter of the femur
Gluteus medius muscle functions
Hip abduction and stabilization of the pelvis during ambulation.
Fracture of the greater trochanter (eg, fragility fracture from a fall) can lead to what?
It can disrupt the integrity of the gluteus medius tendon and result in lateral hip pain with gait instability and weakness of hip abduction
Combined hormonal contraceptives are effective at preventing pregnancy by what?
Combined hormonal contraceptives are effective at preventing pregnancy by decreasing the release of gonadotropins, which suppresses folliculogenesis and inhibits ovulation.
What are the clinical features of paraneoplastic hypercortisolism?
Hypertension, hyperglycemia, edema, and hyperpigmentation.
Unlike nonparaneoplastic Cushing syndrome, central obesity is uncommon
Paraneoplastic hypercortisolism is due to what?
Due to ectopic ACTH secretion.
Paraneoplastic hypercortisolism is most commonly caused by what?
Small cell lung cancer
What are signs of norepinephrine extravasation?
Blanching of a vein into which norepinephrine is being infused together with induration and pallor of the tissues surrounding the IV site are signs of norepinephrine extravasation and resulting vasoconstriction.
Tissue necrosis is best prevented by local injection of an alpha receptor blocking drug, such as phentolamine
With endurance training, the physiologic changes of athlete’s heart allow for increased maximum cardiac output via?
an increase in stroke volume.
The left ventricle undergoes eccentric hypertrophy to increase left ventricular cavity size and improve diastolic filling capacity.
The resulting increase in end-diastolic volume capacity allows for increased stroke volume and cardiac output.
Because end-diastolic volume and stroke volume are both proportionally increased, left ventricular ejection fraction is mostly unchanged.
What are the signs and symptoms of superior vena cava syndrome?
Facial swelling, distended collateral veins, headache, and dyspnea.
What can cause superior vena cava syndrome?
Extrinsic compression of the superior vena cava by a mediastinal mass (eg, malignancy) can cause superior vena cava syndrome, with impaired venous return from the upper body.
What is the most common cause of spontaneous lobar hemorrhage in the elderly?
Cerebral amyloid angiopathy
What are the most common sites of hemorrhage in cerebral amyloid angiopathy?
Occiptal and parietal lobes
What is torsades de pointes?
Torsades de pointes referes to polymorphic ventricular tachycardia that occurs in the setting of a congenital or acquired prolonges QT interval.
What medications cause torsades de pointes?
TdP is most commonly precipitated by medications that prolong the QT interveal such as certain antiarrhythmics (sotalol, quinidine), antipsychotics (haloperidol), and antibiotics (macrolides, fluoroquinolones)
Under anaerobic conditions, NADH transfers electrons to what?
Under anaerobic conditions, NADH transfers electrons to pyruvate to form lactate and regenerate NAD+.
NAD+ is required for what in glycolysis?
NAD+ is required to convert glyceraldehyde-3-phosphate to 1-3-bisphosphoglycerate in glycolysis.
What is the main source of rabies in the US?
Bats
What is suggestive of rabies encephalitis?
Agitation and spasms progressing to coma within weeks of exposure is suggestive of rabies encephalitis.
What is recommended to individuals at high risk for exposure to rabid animals?
Prophylactic vaccination.
The approved vaccines consist of various rhabdovirus strains grown in tissue cell culture and then inactivated.
What is adenomyosis?
Adenomysosis is the abnormal presence of endometrial glands and stroma within the uterine myometrium.
Affected patients with adenomyosis present how?
They are typically multiparous women with dysmenorrhea, heavy menses, and a uniformly enlarged uterus.
An expanding aneurysm in the cavernous portion of the internal carotid artery is most likely to initially cause what?
Initially cause headache and diplopia (ipsilateral lateral rectus weakness) due to compressing or stretching of the abducens nerve (CN VI) as it runs next to the ICA in the cavernous sinus.
What is seen on biopsy of Blastomyces derematitidis?
large, round yeasts with doubly refractile wall and single broad based bud
What is seen on biopsy for Histoplasma capsulatum?
oval yeast cells within macrophages
What is seen on biopsy for Coccidioides immitis?
Thick walled spherules filled with endospores
What is systemic mastocytosis?
It is the abnormal proliferation of mast cells and increased histamine release.
Histamine causes hypersecretion of gastric acid by parietal cells in the stomach as well as a variety of other symptoms (eg, hypotension, flushing, pruritus)
How does syndrome of inappropiate antidiuretic hormone (SIADH) presents?
Presents with hypotonic hyponatremia (ie, low serum osmolality and serum sodium), concentrated urine (ie, high urine osmolality) and euvolemia.
How does carbamazepine cause SIADH?
By increasing antidiuretic hormone secretion and renal sensitivity to ADH
Multiple myeloma should be suspected in elderly patients with any combination of what?
Hypercalcemia, normocytic anemia, bone pain, elevated gamma gap, or renal failure.
Renal failure is commonly caused by light chain cast nephropathy; large, waxy, eosinophilic casts composed of Bence Jones proteins are seen in the tubular lumen.
What is granulomatous inflammation characterized by?
A form of chronic inflammation characterized by aggregates of activated macrophages that assume an epithelioid appearance.
Persistent granulomatous inflammation with subsequent fibrosis can cause organ dysfunction, which is seen in number of granulomatous diseases.
Interstitial lung disease is associated with what?
Interstitial lung disease is associated with decreased lung volumes and increased lung elastic recoil caused by fibrotic interstitial tissue.
The increased elastic recoil results in increased radial traction (outward pulling) on the airways, leading to increased expiratory flow rates when corrected for the low lung volume
Why are preterm infants are at increased risk for hypothermia?
Preterm infants are at increased risk for hypothermia because they have less brown adipose tissue than term infants.
Brown adipose cells, which contain multiple lipid droplets and abundant mitochondria, produce large amounts of heat (ie, thermogenesis) by uncoupling oxidative phosphorlylation with the protein thermogenin.
What can lead to the formation of a varicocele?
Pressure in the left renal vein may become elevated due to compression where the vein crosses the aorta beneath the superior mesenteric artery.
This “nutcracker effect” can cause hematuria and flank pain. Pressure can also be elevated in the left gonadal vein, leading to formation of a varicocele.
What results in hypospadias?
In males, incomplete fusion of the urethral (urogenital) folds results in hypospadias, an abnormal opening of the urethra proximal to the glans penis along the ventral shaft of the penis
Paget disease of bone is characterized by what?
By excessive and disordered bone formation. It commonly affects the skull, long bones, and vertebral column.
What is seen on labs and radiograph for Paget disease of bone?
The increased formation of new bone is associated with an elevated serum alkaline phosphatase level.
Radiographs show lytic or mixed lytic-sclerotic lesions, thickening of cortical and trabecular bone, and bony deformities.
Rinne and Weber results for conductive hearing loss?
In conductive hearing loss, bone conduction will be greater than air conduction (abnormal Rinne test), and the Weber test will lateralize to the affected ear.
Rinne and Weber results for sensorineural hearing loss?
In sensorineural hearing loss, air conduction will be greater than bone conduction (normal Rinne test) and the Weber test will lateralize to the unaffected ear.
What are the traits for hepatitis E virus?
Unenveloped, ssRNA virus spread through fecal oral route
High mortality rate in infected pregnant women
The binding of programmed cell death protein 1 (PD-1) to one of its ligands (PD-L1) downregulates the immune response by?
Inhibiting cytotoxic T cells.
Many types of cancers evade immunodetection by increasing expression of PD-L1 on their surface.
Monoclonal antibodies against PD-1 upregulate the T cell response and promote tumor cell apoptosis.
Aspergillus fumigatus shows what on biopsy?
This fungus produces thin, septate hyphae with acute, V shaped branching, causing invasive aspergillosis, aspergillomas, and allergic bronchopulmonary aspergillosis.
Immunosuppressed are at risk.
The anterior cerebral artery supplies what?
The medial aspects of the frontal and parietal lobes
Occulsion of the anterior cerebral artery can lead to?
Sensory and motor deficits of the contralateral leg.
Occulsion of the anterior cerebral artery distal to the anterior communicating artery can lead to more severe symptoms because there is no collateral blood flow from the Circle of Willis
Amlodipine is a dihydropyridine calcium channel blocker commonly used as monotherapy or in combination with other agents for treatment of hypertension. What are the major side effects?
Headache, flushing, dizziness, and peripheral edema.
What is pulsus paradoxus?
A decrease in systolic blood pressure of >10 mmHg with inspiration
Where is pulsis paradoxus most commonly seen?
In patients with cardiac tamponade but can also occur in severe asthma, chronic obstructive pulmonary disease, and constrictive pericarditis.
What are the causes of pulsus paradoxus in the absence of significant pericardial disease?
Asthma and chronic obstructive pulmonary disease (COPD)
How do beta-adrenergic agonists work to control acute asthma and COPD exacerbations?
By causing bronchial smooth muscle relaxation via increased intracellular cAMP
What is acute disseminated intravascular coagulation?
It is a consumptive coagulopathy linked to severe trauma.
Widespread formation of microvascular thrombi leads to consumption of platelets, coagulation factors, and fibrinogen.
Most patients have bleeding complications (eg, oozing from venipuncture/catheter sites) and end organ damages to the lungs and kidneys.
What are the labs for disseminated intravascular coagulation?
low protein C/S and fibrinolysis elevated D-dimer
What is the most common cause of elevated platelet count in all age groups?
Reactive thrombocytosis
What is reactive thrombocytosis caused by?
Caused by high levels of inflammatory cytokines (eg, IL-6) which prompt the liver to release thrombopoietin.
Seen in chronic infection, rheumatologic disease, and burns; can also occur with hemolysis and iron deficiency anemia.
Tubular fluid concentration along the proximal tubule goes in the order of?
Creatinine
Urea
Sodium or Potassium
Bicarbonate
Glucose or Amino acids
The concentrations of creatinine and urea increase as fluid runs along the proximal tubule, whereas the concentrations of bicarbonate, glucose, and amino acids decrease. Sodium and potassium are reabsorbed with water in the proximal tubule, resulting in no concentration change.
Anterior humerus dislocation will show what symptoms and what nerve injury?
Flattening of the deltoid muscle with acromial prominence after a shoulder injury suggests an anterior humerus dislocation.
This injury most commonly results from a blow to an externally rotated and abducted arm.
There is often associated axillary nerve injury, resulting in deltoid paralysis and loss of sensation over the lateral shoulder.
Prolonged use of GnRH receptor agonists (eg, leuprolide) will do what?
Continuously administered GnRH receptor agonists (eg, leuprolide) initially stimulate pituitary FSH and ovarian estrogren secretion.
However, prolonged use eventually inhibits endogenous GnRH release and downregulares pituitary GnRH receptors, causing decreased GnRH, FSH, and estrogen levels.
The resulting hypogonadotropic, hypogonadal state induces amenorrhea, thereby improving dysmenorrhea associated with endometriosis.
