Uworld20 Flashcards
What is a femoral nerve block?
A femoral nerve block below the inguinal ligament (ie, in the inguinal crease) will anesthetize the skin and muscles of the anterior thigh, femur, and knee.
This type of block can be used in patients requiring tendon repair after a knee injury (eg, quadriceps rupture)
Acute onset bloody diarrhea is most commonly due to?
E coli O157:H7, Shigella, or Campylobacter infection.
Shigella infection also classically causes high fever and left sided abdominal tenderness (due to rectosigmoid involvement) and often occurs in outbreaks (eg, day care center)
How can head trauma cause anosmia?
Olfactory signals are relayed via the olfactory nerve (CN I) through the cribriform plate to the olfactory bulb, which then projects to the primary olfactory cortex in the medial temporal lobe.
Head trauma can tear olfactory nerve (CNI) rootlets as they cross the cribriform plate, causing anosmia. Anosmia is often interpreted by patients as loss of taste.
What is a fibroadenoma?
Fibroadenomas are the most common benign tumor of the breast. They are characterized histologically by a myxoid stroma that encircles and sometimes compresses epithelium-lined glandular and cystic spaces
The earliest morphologic change that occurs after a superficial thermal burn is?
erythema due to the release of preformed mediators (eg, histamine) from mast cells.
Deeper (eg, partial-thickness) burn wounds form blisters due to fluid extravasation through gaps between damaged venule endothelial cells
What can happen to the respiratory system during a panic attack?
Panic attacks are typically accompanied by hyperventilation, leading to hypocapnia.
Cerebral blood flow is directly related to the arterial partial pressure of CO2; therefore, hypocapnia can lead to reduced cerebral blood flow and symptoms of cerebral hypoperfusion (eg, blurred vision, dizziness, lightheadedness)
What is a S3?
S3 is a low frequency sound that occurs just after S2 and is typically associated with ventricular volume overload.
It is commonly heard in patients with mitral or aortic regurgitation or heart failure with reduced ejection fraction (eg, dilated cardiomyopathy)
What are the physiologic adaptations in response to hypothermia?
The hypothalamus controls thermoregulation by promoting alterations in the autonomic nervous system and the adrenal and thyroid axes.
Physiologic adaptations in response to hypothermia include increased sympathetic activity and thyroid hormone release, shivering, and peripheral vasoconstriction. These actions normalize body temperature by reducing heat loss and increasing metabolic rate (promoting thermogenesis)
What is Clostridium septicum?
a spore forming, exotoxin-producing, gram+ organism that is the most common cause of spontaneous gas gangrene (eg, rapid onset pain, hemorrhagic bullae, tissue crepitus). Underlying colonic malignancy is the greatest risk factor for infection
MOA of ezetimibe
Ezetimibe reduces intestinal absorption of cholesterol. As a result, the amount of dietary cholesterol reaching the liver decreases. To compensate, the liver increases LDL receptor expression, which draws cholesterol out of the circulation
What are the ocular manifestations in giant cell arteritis (temporal arteritis)?
Can lead to rapid, severe, and irreversible vision loss.
Involvement of the ciliary arteries in GCA leads to anterior ischemic optic neuropathy, which presents with a painless, rapidly progressive decrease in visual acuity.
Treatment includes systemic glucocorticoids (eg, prednisone, methylprednisolone)
How is Neisseria meningitidis transmitted?
primarily by aerozolized droplets and subsequently colonizes the nasopharyngeal epithelium.
Penetration of the epithelium can lead to bloodstream infection.
Spread to the meninges occurs via transcellular penetration of the cerebral capillary endothelium or entry at the choroid plexus
Lead inhibits what?
Young children who resides in homes built before 1978 are at significant risk for lead toxicity.
Lead directly inhibits ferrochelatase and aminolevulinic acid dehydrates, resulting in anemia, ALA accumulation, and elevated zinc protoporphyrin levels.
Neurotoxicity is also a significant long term complication
The underlying biochemical feature of megalobastosis is?
defect in DNA synthesis. In patients with chronic alcohol use, megaloblastic macrocytic anemia can result from a nutritional deficiency of vit B12 or folate, which impairs synthesis of purine and pyrimidine bases
Patients undergoing solid organ transplantation are at increased risk of gout due to?
meds that impair renal clearance of uric acid. Cyclosporine is particularly associated with gout in the post-transplantation period due to decreased uric acid excretion
What is Reye syndrome?
acute liver failure (hepatomegaly, elevated aminotransferases, coagulopathy) and rapidly progressive encephalopathy related to hyperammonemia.
It usually develops in susceptible children during a viral infection after administration of salicylates (eg, aspirin), which can cause damage to the mitochondria and impair fatty acid beta oxidation within hepatocytes
How does disseminated gonococcal infection present?
Neisseria gonorrhoeae is spread sexually by genitourinary secretions and can be prevented by the consistent use of condoms.
genitourinary infections are often asymptomatic, which increases the risk of spread through the bloodstream, leading to disseminated gonococcal infection.
Patients with disseminated disease typically present with the triad of polyarthralgia, tenosynovitis, and dermatitis or purulent arthritis.
What is hairy cell leukemia?
an indolent B cell neoplasm predominantly found in middle aged men and characterized by bone marrow failure and infiltration into the reticuloendothelial system, causing massive splenomegaly.
Other typically features include a dry tap (unsuccessful bone marrow aspiration) and the presence of lymphocytes with cytoplasmic projections
What is the p-value?
the probability of obtaining a result (ie, sample estimate) at least as large as the one observed when the population value claimed in the null hypothesis is assumed to be true.
A p-value <0.05 = statistically significant
GERD is a common physiologic phenomenon in infants and is due to?
low tone of an immature lower esophageal sphincter. It is characterized by frequent spit up in an otherwise asymptomatic patient with appropriate weight gain
What is a Councilman body?
Intravenous drug use is a risk factor for acute viral hepatitis, which is marked by panlobular inflammation, hepatocyte injury, and cell death.
To control the infection, cytotoxic T cell-mediated signals cause hepatocyte apoptosis, which is characterized by Councilman bodies ( round, intensely eosinophilic bodies)
What is a Dupuytren contracture?
caused by progressive fibrosis of the superficial palmar fascia due to excessive fibroblast proliferation.
Pathognomonic fibrotic nodules and cords form along the flexor tendons, limiting extension of the affected digits.
What is the most common cause of encephalitis outbreaks in the US?
Arboviruses, small RNA viruses transmitted by biting arthropods.
Because no vaccines are currently available, prevention primarily involves eliminating the vector arthropods (eg, infected mosquitos)
What are the neutrophil chemotactic agents?
Leukotriene B4, C5a, IL-8, and 5-HETE (leukotriene precursor)
Function of the rough endoplasmic reticulum?
covered with ribosomes and is involved in the transfer of proteins to the cell membrane and extracellular space.
RER is well developed in protein secreting cells.
Smooth endoplasmic reticulum function
lacks surface ribosomes and functions in lipid synthesis, carbohydrate metabolism, and detoxification of harmful substances
What is retinal artery occlusion?
a cause of acute, painless, monocular vision loss.
It is usually caused by thromboembolic complications of atherosclerosis traveling from the internal carotid artery and through the ophthalmic artery
The majority of left ventricular myocardial perfusion occurs during?
The high systolic intraventricular pressure and wall stress of the left ventricle prevent myocardial perfusion during systole; therefore the majority of left ventricular myocardial perfusion occurs during diastole.
Shorter duration of diastole is the major limiting factor for coronary blood supply to the left ventricular myocardium during periods of tachycardia (eg, exercise)
What is Kaposi sarcoma?
a vascular neoplasm that often presents in HIV+ people, may involve the GI tract, causing bloody diarrhea, weight loss, and abdominal pain.
Endoscopy: red-violet maculopapular lesions, raised hemorrhagic nodules, or polypoid masses.
Histo: spindle shaped endothelial cells, slit like vascular spaces, and extravasated RBCs
MI involving leads I and aVL means infarction involving which artery?
Leads I and aVL correspond to the lateral limb leads on ECG.
Therefore, ST elevation or Q waves in these leads are indicative of infarction involving the lateral aspect of the left ventricle, which is supplied by the left circumflex artery
What is sepsis?
Sepsis is a host inflammatory response to infection that can lead to multiple organ dysfunction due to defective mitochondrial oxidative respiration, resulting in a widespread dissociation between oxygen delivery and extraction.
This manifests as elevated central venous oxygen saturation
Prolonged beta blockade leads to?
When exposed to a prolonged environmental stimulus, cells can adjust their sensitivity to the stimulus by upregulating or downregulating surface membrane receptors.
Prolonged beta blockade leads to upregulation of beta-adrenergic receptors and increased sensitivity to circulating catecholamines, causing an enhanced beta-adrenergic response on abrupt beta blocker cessation (ie, beta blocker withdrawal syndrome)
What is medullary thyroid cancer?
a neuroendocrine tumor that arises from parafollicular calcitonin-secreting C cells.
It is characterized by nests or sheets of polygonal or spindle-shaped cells with extracellular amyloid deposits derived from calcitonin
What are the signs for renal cell carcinoma?
Classic signs and symptoms of renal cell carcinoma include hematuria, an abdominal mass, flank pain, and weight loss.
Hypercalcemia and erythrocytosis are common paraneoplastic syndromes associated with RCC
What causes cataracts at an early age?
Cataracts are related primarily to chronic photooxidative injury.
Most patients with cataracts first develop symptoms at age >60 but exposure to systemic or ophthalmic glucocorticoids can cause cataracts at an early age.
Other causes of premature cataract formation include diabetes mellitus, ocular trauma, and external radiation exposure
Difference between first and second generation antipyschotics
Second generation are associated with a lower risk of extrapyramidal (acute dystonia, akathisia, parkinsonism) side effects compared with first generation antipsychotics but may cause adverse metabolic effects
The most important determinant of intravenous infusion rate is?
the radius (diameter) of the intravenous catheter.
For patients requiring a rapid blood transfusion, the shortest possible catheter with the widest possible diameter (eg, a large-bore peripheral intravenous catheter) should be selected
What causes a lingual thyroid?
The thyroid gland is formed from evagination of the pharyngeal epithelium and descends to the lower neck.
Due to failure of migration, the thyroid can reside anywhere along the thyroglossal duct’s usual path, including the tongue (lingual thyroid)
Traits for S saprophyticus
S saprophyticus is responsible for almost half of all UTIs in sexually active young women.
Belongs to coagulase negative staphylococci and is unique because it is resistant to novobiocin
