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.
