Uworld 4 Flashcards
Vasovagal syncope results from what?
Vasovagal syncope typically involves a trigger (eg, prolonged standing), a prodrome (eg, warmth, light headedness) and rapid recovery (eg within 1-2 min).
It results from a transient, autonomic nervous system-mediated cardioinhibitory and vasodepressor response.
What is a trait of adenosine deaminase (ADA) inhibition/absence?
It is highly lymphocytotoxic.
Meds that block ADA are used to treat lymphocyte-derived cancers, like hairy cell.
Inherited gene mutations in adenosine deaminase leads to?
the autosomal recessive disease of severe combined immunodeficiency
What does the anterior cerebral artery supply?
The medial aspects of the frontal and parietal lobes, which contain the upper motor neurons responsible for contralateral lower extremity motor control.
Thromoboembolic occulsion of the anterior cerebral artery results in?
Contralateral lower extremity weakness with hyperreflexia
What is the pathogenesis of rheumatoid arthritis?
Early activation of CD4+T cells (especially Th1 and Th17) with release of cytokines such as tumor necrosis factor-alpha and IL-1 that cause destruction of cartilage and bone.
Monoclonal antibodies that inhibit tumor necrosis factor-alpha or IL-1 receptors can slow progression of the disease.
What can happen if you use lithium during pregnancy?
Lithium is commonly used to treat bipolar disorder.
Its use during pregnancy is associated with Ebstein’s anomaly, which is characterized by apical displacement of the tricuspid valve leaflets, decreased right ventricular volume, and atrialization of the right ventricle.
What is S1 radiculopathy in sciatica?
Resulting in pain/sensory loss down the posterior thigh and calf to the lateral aspect of the foot.
Patients may also have weakness on thigh extenson, knee flexion, and foot plantarflexion with an absent Achilles reflex
What is seen on histo for aortic root disease with patients who have Marfan?
Marfan syndrome involves a deleterious mutation in fibrillin that mainly affects the structural integrity of the cardiovascular and musculoskeletal systems.
Aortic root disease predisposes to aortic dissection, which can present with sudden-onset chest or back pain, acute aortic regurgitation and heart failure.
Histo: fragmentation and loss of the elastic lamellae with fibrosis and cystic medial degeneration
What is stress hyperglycemia?
Transiently elevated blood glucose levels in the context of severe illness (eg, sepsis, burns, major hemorrhage) in patients without preexisting diabetes mellitus.
Cortisol and catecholamines released in response to severe metabolic stress act on the liver to increase glycogenolysis and gluconeogenesis.
Pulmonary embolism typically presents with hypoxemia due to?
ventilation/perfusion mismatch and acute resp alkalosis (hypocapnia) due to hyperventilation
Chronic alcohol use will act on what receptors?
Downregulates inhibitory GABA receptors and upregulates excitatory NMDA glutamate receptors.
Sudden cessation of alcohol leads to what?
decreased GABA activity and increased glutamate activity, resulting in CNS overexcitation (eg, agitation, disorientation, tremulousness, autonomic hyperactivity)
What is seen on MRI for vascular dementia?
Multiple small infarcts, microbleeds, and areas of hyperintensity in the white matter that represent demyelination or axon loss
What is primary hyperaldosteronism cause by? Clinical findings?
Caused by excessive aldosterone secretion, typically due to an aldosterone-producing adrenal adenoma or bilateral nodular hyperplasia of the zona glomerulosa.
CF: hypertension, low plasma renin, hypokalemia, and metabolic alkalosis.
What is severe combined immune deficiency? Labs?
Characterized by combined T and B cell dysfunction.
Bacterial and viral infections, mucocutaneous candidiasis, persistent diarrhea, and failure to thrive.
Labs: absent T cells and hypogammaglobulinemia
The thymic shadow is not present due to severe T cell def
Cervical spine trauma can lead to dissection of the vertebral artery, resulting in?
Resulting in infarction of the lateral medulla and causing vertigo/nystagmus, ataxia, loss of pain/temp sensation in the ipsilateral face and contralateral body, bulbar weakness, and ipsilateral Horner syndrome.
MOA of aminoglycosides (like gentamicin)
They inhibit genetic code reading and protein synthesis by binding to the prokaryotic 30S ribosomal subunit.
How does clonidine cause orthostatic syncope?
Clonidine, an antihypertensive agent. stimulates central alpha 2 adrenergic receptors, causing a decrease in presynaptic release of norepinephrine and a decrease in sympathetic outflow.
This prevents the normal baroceptor-mediated increase in peripheral vascular resistance and heart rate during standing and can cause orthostatic syncope.
What are the traits of Actinomyces?
G+ branching, filamentous bacteria that may cause cervicofacial infections when introduced to the submucosa during mechanical trauma (eg tooth extraction).
Manifestations: slowly enlarging, non painful, chronic mandibular mass that evolves into multiple abscesses and sinus tracts draining yellow-orange sulfur granules
What is Henoch-Schonlein purpura?
IgA mediated, leukocytoclastic vasculitis that presents with palpable purport, arthralgia/arthritis, abdominal pain, and/or hematuria
Renal involvement is due to mesangial deposition of IgA immune complexes with subsequent mesangial cell proliferation, neutrophilic infiltration, and glomerular damage
How is Helicobacter pylori associated with gastric MALT?
Helicobacter pylori is associated with gastric MALT lymphoma due to chronic stimulation of the immune response; the continuous cell dvision predisposes to accumulation of mutations that result in aberrant B-cell proliferation.
Treatment of H pylori can induce remission in the majority of cases of early stage gastric MALT lymphomas
Patients with profound and prolonged neutropenia are at especially high risk for fungal infections. What are the common ones?
Aspergillus and Candida
What is the treatment of malignant hyperthermia?
Dantrolene, which blocks ryanodine receptors to prevent the release of calcium from the sarcoplasmic reticulum into the cytoplasm of skeletal muscle fibers
What is malignant hyperthermia?
Widespread muscle rigidity after administration of inhalation anesthetics and/or succinylcholine to genetically susceptible individuals.
What anticoagulant can inactivate thrombin?
Unfractionated heparin is able to bind to both antithrombin and thrombin to allow antithrombin to inactivate thrombin
Gustatory (taste) innervation of the anterior 2/3 tongue is provided by?
chorda tympani branch of the facial nerve
Why is Pierre Robin characterized as a sequence?
Because the primary defect (hypoplasia of the mandibular prominence) leads to a cascade of further malformations (ie, micrognathia, posteriorly displaced tongue, U shaped cleft palate)
Secretin is produced by which cells?
By S cells in the duodenal mucosa in response to stimulation by intraluminal acidity.
What is the action of secretin?
Secretin stimulates the release of bicarbonate-rich secretions from the exocrine pancreas, which is the major source of acid-neutralizing bicarbonate entering the duodenum
Chronic granulomatous disease is due to?
Chronic granulomatous disease is a primary immunodeficiency due to impaired NADPH oxidase, an enzyme that generates reactive oxygen species in phagolysosomes.
Chronic granulomatous disease has recurrent infections with what?
Diminished intracellular killing within neutrophils leads to susceptibility to recurrent infection with catalase producing bacteria (eg Staph aureus, Nocardia, Burkholderia, Serratia) and fungi (eg Aspergillus)
Pulmonary arterial hypertension typically affects young women and can be familial. It is characterized by what?
By luminal narrowing of the pulmonary arteries and arterioles, with medial hypertrophy, intimal fibrosis, and the eventual development of plexiform lesions.
What is the MOA of Bosentan?
Competitive antagonist of endothelin receptors used for the treatment of pulmonary arterial hypertension
What is celiac disease?
An immune-mediated disorder triggered by dietary gluten that causes small-bowel malabsorption. Because the proximal small bowel is primarily affected, iron deficiency leading to microcytic anemia is common.
What is seen on histo for celiac disease?
Intraepithelial lymphocytosis, loss of intestinal villi, and mucosal atrophy
What is the MOA of protease inhibitors (atazanavir, darunavir, indinavir, ritonavir: -navir)?
HIV antiretroviral meds that inhibit cleavage of the polypeptide precursor into mature viral proteins
What is the side effects of protease inhibitors (atazanavir, darunavir, indinavir, ritonavir: -navir)?
Hyperglycemia, lipodystrophy, and drug-drug interactions due to inhibition of cytochrome P450
What can Clostridium perfringens cause?
Causes late-onset food poisoning and clostridial myonecrosis (gas gangrene).
The food poisoning is toxin-mediated, late onset, and causes transient watery diarrhea.
The jaw jerk reflex afferent and efferent pathways are mediated by what nerves?
The jaw jerk reflex is a pathological cranial nerve reflex present in patients with bilateral upper motor neuron lesions, such as amyotrophic lateral sclerosis.
Both the afferent and efferent pathways are mediated by the mandibular division of the trigeminal nerve (CN V3)
Acid maltase (alpha-glucosidase) deficiency presents how?
Presents in early infancy with cardiomegaly, macroglossia, and profound muscular hypotonia.
Abnormal glycogen accumulation within lysosomal vesicles is seen on muscle biopsy.
What are the traits for Strep pyogenes?
PYR-positive, beta-hemolytic, G+ coccus that grows in chains
Monomicrobial cases of necrotizing fasciitis is due to?
Necrotizing fasciitis is a severe infection of the subcutaneous tissue and deep fascia and is a surgical emergency,
Often polymicrobial, but monomicrobial cases due to Strep pyogenes (group A strep)
