Uworld36 Flashcards

Question

What does the different measurements of RR mean?

Answer 1

the relative risk (RR) is a measure of association: RR < 1 = lower risk of disease in the exposed group relative to the nonexposured RR = 1 = no association between exposure and disease RR > 1 = greater risk of disease in the exposed group relative to the nonexposed

Answer 2

primarily an N-methyl-D-asparate antagonist, with lesser effects on the reuptake inhibition of biogenic amines and other receptors. It can have dissociative and anesthetic effects but may also cause psychosis and severe agitation, leading to violent trauma. Ataxia horizontal and vertical nystagmus and memory loss can also be present

Answer 3

Mycoplasma pneumoniae. Because this pathogen lacks a cell wall, it does not show up on gram stain and cannot be treated with beta lactam antibiotics. Protein synthesis inhibitors (macrolides, tetracyclines) are the treatment of choice

Answer 4

are most prominent in the lung periphery and include a heterogenous mixture of chronic inflammation and patchy interstitial fibrosis, focal fibroblast proliferation, and formation of fibrotic cystic spaces in a honeycomb pattern

Answer 5

caused by autoantibodies against postsynaptic nicotinic acetylcholine receptors, leading to fewer functional receptors and fatigable muscle weakness. Nondepolarizing neuromuscular blocking agents (vecuronium) are competitive antagonists of nicotinic receptors; because of the depletion of receptors, patients with MG are extremely sensitive to these agents

Answer 6

Heart failure leads to reduced liver and kidney perfusion, resulting in reduced drug clearance. Metformin is excreted unchanged by the kidney; therefore, patients with significant renal insufficiency due to heart failure or other causes (chronic kidney disease) are at increased risk of toxicity (lactic acidosis)

Answer 7

a plasma cell malignancy that replicates in the bone marrow and causes osteolytic bone lesions, bone destruction, hypercalcemia, and pathologic fractures. Histopath: replacement of the normal bone marrow with plasma cells and plasmablasts

Answer 8

Normal blood glucose levels are maintained by the opposing effects of insulin and glucagon. Glucagon stimulates hepatic glycogenolysis and gluconeogenesis, whereas insulin increases peripheral glucose uptake and inhibits lipolysis and ketoacid formation. Insulin also suppresses glucagon release

Answer 9

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).

Answer 10

In acute pancreatitis, release of lipase and other digestive enzymes causes fat necrosis with precipitation of insoluble calcium salts (saponification), imparting a chalky white gross appearance. Microscope: necrotic fat cells with calcium deposits are seen. In severe cases, fat necrosis can involve the mesentery, omentum, and other parts of the abdominal cavity

Answer 11

by the ingestion of a preformed, heat stable enterotoxin that induces rapid onset (<6hours) nausea and vomiting. Most cases arise due to improper food handling and storage. Common culprit foods include eggs, dairy, mayonnaise based salads

Answer 12

gallstones obstructing the cystic duct. The diagnosis can be made by identifying signs of gallbladder inflammation (wall thickening, pericholecystic fluid) on ultrasound. When ultrasound is inconclusive, nuclear medicine hepatobiliary scanning (cholescintigraphy) can be used to assess cystic duct patency and make the diagnosis

Answer 13

hyperplasia of the submucosal bronchial glands is the major contributor to bronchial wall thickening in chronic bronchitis. The Reid index is the ratio of the thickness of the submucosal bronchial glands to the thickness of the bronchial wall between the epithelial basement membrane and the bronchial cartilage

Answer 14

Pituitary tumors can present with headaches, bitemporal hemianopsia, and hypopitutariusm; the most common hormonally active (functional) adenomas are prolactin-secreting adenomas (prolactinomas). Prolactinomas can cause galactorrhea and amenorrhea in women. In men, they often present with hypogonadism

Answer 15

Several enzymes involved in glucose metabolism (pyruvate dehydrogenase, alpha ketoglutarate dehydrogenase) require thiamine as a cofactor. The adminstration of glucose to thiamine-deficient patients (chronic alcohol use) can precipitate Wernicke encephalopathy (acute confusion, opththalmoplegia, ataxia) due to rapid thiamine consumption

Answer 16

a fast acting, depolarizing neuromuscular blocking agent used for rapid sequence intubation that causes equal reduction of all 4 twitches during train of four stimulation (phase I blockade). Prolonged adminstration of succinylcholine or use in patients with abnormal plasma cholinesterase activity causes transition to a phase II (nondepolarizing) block, seen as a progressive reduction in each of the 4 twitches

Answer 17

Deep intraparenchymal hemorrhage is most commonly caused by hypertensive vasculopathy of the small penetrating branches of the cerebral arteries (charcot-bouchard aneurysm rupture). This is in contrast to rupture of saccular aneurysms, which typically cause subarachnoid hemorrhage

Answer 18

a rare condition characterized by progressive respiratory dysfunction due to the accumulation of surfactant (periodic acid-Schiff positive material forming lamellar bodies) within the alveolar spaces. The condition occurs most often due to the impaired clearance of surfactant by alveolar macrophages (decreased granulocyte monocyte colony stimulating factor signaling)

Answer 19

BPH can increase resistance to urine flow in the urethra and lead to incomplete bladder emptying during micturition. The residual urine can act as a growth medium for pathogenic bacteria and increase the risk for UTI.

Answer 20

endometrial glands (lines by columnar epithelium), endometrial stroma, and hemosiderin. Endometriosis commonly involves the ovary, which is covered by a simple cuboidal surface epithelium

Answer 21

Drug induced neutropenia is the major side effect of the first line meds (methimazole, propylthiouracil) used to treat Graves disease. Initial manifestations are fever and oropharyngeal ulcers

Answer 22

In contrast to angina, the chest pain of pericarditis is sharp and pleuritic and may be exacerbated by swallowing or coughing. Peri-infarction pericarditis occurs between 2 and 4 days following a transmural myocardial infarction. PIP is an inflammatory reaction to cardiac muscle necrosis that occurs in the adjacent pericardium.

Answer 23

The celiac trunk is the first main branch of the abdominal aorta; it provides oxygenated blood to the spleen, stomach, liver, abdominal esophagus, and parts of the duodenum and pancreas. The proper hepatic artery branches off the common hepatic artery from the celiac trunk and provides arterial blood supply to the liver

Answer 24

Staghorn calculi are large renal stones that take the shape of the renal calyces. They are composed primarily of struvite (magnesium ammonium phosphate) and are associated with recurrent upper UTIs by urease producing organism (proteus, klebsiella). hydrolysis of urea yields ammonia, which alkalinizes the urine and facilitates precipitation of struvite crystals.

Answer 25

In patients with chronic aortic stenosis and concentric left ventricular hypertrophy, atrial contraction contributes significantly to left ventricular filling. Loss of atrial contraction due to atrial fibrillation can reduce left ventricular preload and cardiac output sufficiently to cause systemic hypotension. Decreased forward filling of the left ventricle can also result in backup of blood in the left atrium and pulmonary veins, leading to acute pulmonary edema

Answer 26

the displacement of the annular ligament into the radiohumeral joint, classically resulting from sudden axial traction (pulling) on the arm of a child age <5. Although most patients do not have any obvious swelling or deformity, they avoid moving the arm due to pain and hold it with the elbow flexed and forearm pronated

Answer 27

Direct arteriolar vasodilators lower blood pressure but trigger reflex sympathetic activation and stimulate the renin-angiotensin-aldosterone axis. This results in tachycardia and edema. To counteract such compensatory effects, these agents are often given in combo with sympatholytics and diuretics

Answer 28

ventricular repolarization, which is primarily controlled by voltage gated potassium channels. Congenital mutations impairing these potassium channels cause prolongation of the QT interval. Affected patients are at increased risk for torsade de pointes, a type of polymorphic ventricular tachycardia that can cause syncope or sudden cardiac death

Answer 29

occurs more commonly in elderly postoperative patietns who are intubated or dehydrated. Staph aureus is the most common bacterial etiology. Diagnosis can be confirmed by imaging and an elevated serum amylase level (with a normal serum lipase level and no evidence of pancreatitis)

Answer 30

synovial hyperpalsia, an inflammatory infiltrate, and synovial angiogenesis. The joint space often becomes replaced by pannus, an invasive mass composed of fibroblast-like synovial cells, granulation tissue, and inflammatory cells that can erode into the articular cartilage and underlying bone

Answer 31

animal oral flora, the most common of which is Pasteurella

Answer 32

contain gamma-globin instead of beta. Patients with homozygotic beta-thalassemia (beta-thlassemia major) are asymptomatic at birth due to the presence of gamma-globins and HbF. Switching to HbA production and the cessation of gamma-globin synthesis precipitates the symptoms of beta-thalassemia

Answer 33

Cricothyrotomy is indicated when an emergency airway is required and orotrachael or nasotracheal intubation is either unsuccessful or contraindicated. The cricothyrotomy incision passes through the superficial cervical fascia, pretracheal fascia, and the cricothyroid membrane.

Answer 34

presents with acute testicular pain, tenderness, and pyuria. It is caused by retrograde passage of organisms from the urethra into the ejaculatory duct and vas deferens. The microbiology is largely influenced by patient age: young men is usually due to sexually acquired infections (chlamydia trachomatis, neisseria gonorrhoeae), whereas older men >35 it is usually due to gram negative colonic flora

Answer 35

cryptosporidium may lead to severe and protracted diarrhea in immunocompromised patients (advanced HIV) Diagnosis is usually made by visualizing acid-fast staining oocytes in the stool. The presence of basophilic organisms lining the brush border on intestinal histopath is also diagnostic

Answer 36

lamotrigine can be used to treat focal and generalized seizures and works by blocking voltage gated sodium channels. Stevens-johnson syndrome/toxic epidermal necrolysis is a rare, life threatening adverse effect characterized by flu-like symptoms followed by widespread mucocutaneous epidermal necrosis

Answer 37

presents with involuntary, rapid, irregular jerking movements involving the face, arms, and legs. It occurs months after group A streptococcal infection and is one of the major clinical manifestations of acute rheumatic fever. Patients with this condition carry a high risk of chronic valvular disease.

Answer 38

Shigella initially invades the intestinal epithelial barrier by passing through microfold (M) cells overlying ileal Peyer patches. Once at the basolateral mucosal surface, Shigella can more efficiently enter enterocytes and then spread laterally into other epithelial cells, causing cell death and ulceration with bloody/mucoid diarrhea

Answer 39

the bladder trigone is formed by 2 slit like ureteric orifices and the internal urethral opening. Blood within the ureteric orifice suggests upper urinary bleeding originating in the kidney (eg, renal papillary necrosis) or ureter.

Answer 40

a metaplastic condition in which the normal squamous epithelium of the distal esophagus is replaced by intestinal type columnar epithelium. It occurs most often in longstanding acid reflux and is associated with an increased risk of adenocarcinoma

Answer 41

vertical transmission of hep B from pregnant females to the unborn child can occur in women with active hep b infection. the presence of HBeAg (marker of viral replication and increased infectivity) in the mother greatly increases the risk of vertical transmission of the virus. Because of this concern, the newborns of all mothers with active hep B are passively immunized at birth with hep B immune globulin (HBIG), followed by active immunization with recombinant HBV vaccine

Answer 42

commonly causes a harsh, holosystolic murmur at the left lower sternal border; the murmur increases in intensity during maneuvers that increase left ventricular afterload (handgrip maneuver). A small VSD is usually asymptomatic and produces a relatively loud murmur due to a high interventricular pressure gradient

Answer 43

ectopic implantation of endometrial glands and stroma in the abdominopelvic cavity. Bladder implants may also result in dysuria while rectovaginal implants may cause dyschezia, rectovaginal nodularity, and pelvic fibrosis (immobile uterus)

Answer 44

most commonly due to hippocampal sclerosis. histopath of hippocampal sclerosis: atrophy of the hippocampal neurons with marked reactive gliosis (astrocyte proliferation in response to injury)

Answer 45

the ventricular stretch and strain that typically occurs with volume overload. BNP, along with atrial natriuretic peptide secreted by the atrial myocardium, stimulates vasodilation and salt and water excretion to help relieve volume overload

Answer 46

hepcidin is synthesized by the liver that acts as the central regulator of iron homeostasis. High iron levels and inflammatory conditions increase the synthesis of hepcidin; hypoxia and increased erythropoiesis act to lower hepcidin levels. Low hepcidin levels increase intestinal iron absorption and stimulate iron release by macrophages

Answer 47

metformin reduces hepatic gluconeogenesis and release of glucose into circulation; increases peripheral glucose uptake and utilization; and reduces circulating lipid levels. Circulating insulin levels are unchanged or slightly decreased; therefore, metformin carries low risk of hypoglycemia. Metformin reduces caloric intake due to decreased appetite and decreased absorption of glucose, leading to modest weight loss.

Answer 48

intracellular accumulation of Na and Ca. The increased intracellular solute concentration draws free water into the cell, causing the cellular and mitochondiral swelling that is observed histologically

Answer 49

a chronic autoimmune liver disease characterized by lymphocytic infiltrates and destruction of small and midsized intrahepatic bile ducts. Similar findings are seen in hepatic graft vs host disease, highlighting the immunologic etiology of both disorders.

Answer 50

Staph epidermidis, a gram+ coccus that grows in clusters, in a skin commensal that is a common cause of infection in patients with prosthetic devices such as artifical joints or heart valves. Unlike S aureus, S epidermidis is coagulase-negative. Unlike S saprophyticus (another coagulase-negative staphylococci species), S epidermidis is susceptible to novobiocin.

Answer 51

most commonly results from local extension of vertebral metastases into the epidural space. Presenting symptoms: severe back pain (often worse at night), motor weakness, and/or sensory deficits. Urinary and fecal retention or incontinence are common late stage findings

Answer 52

can occur when a large area of cells is exposed to carcinogens that induce mutations, leading to a higher risk of forming cancers.

Answer 53

an immunosuppressant that functions via inhibition of purine synthesis by its pharmacologically active 6-thioguanine metabolites. In addition to the desired effect of reduced lymphocyte proliferation, the proliferation of other hematologic cell lines (neutrophils, erythrocytes, platelets) is reduced, leading to a common adverse effect of pancytopenia

Answer 54

chronic uric acid-lowering therapy is recommended for patients with goat who have frequent gouty attacks, uric acid kidney stones, tophi, or chronic joint destruction from gout. Xanthine oxidase inhibitors are the preferred treatment.

Answer 55

Adding carbidopa can reduce most of the peripheral adverse effects of levodopa. However, the central effects of dopamine (anxiety, agitation, behavioral changes) from levodopa can worsen with the addition of carbidopa because more dopamine becomes available in the brain.

Answer 56

NNT is the number of patients who need to receive a treatment to prevent 1 additional negative event. NNT is the inverse of the absolute risk reduction. The lower the NNT, the more effective the treatment because fewer patients need to be treated to prevent 1 additional negative event.

Answer 57

astrocyte hypertrophy and proliferation (gliosis). This process leads to the formation of a glial scar, which compensates for the volume loss that occurs after neuronal death.

Answer 58

diffuse epidermal hyperplasia with elongated and clubbed rete ridges (corresponding to the typical erythematous plaques), confluent parakeratosis (producing the characteristic silvery scales seen on exam), and dilated capillaries in the dermal papillae (pinpoint bleeding)

Answer 59

a peripheral neuropathy characterized by pain/paresthesia in a median nerve distribution (palmar surface on the first 3 digits and radial half of the 4th digit), weakness on thumb abduction/opposition, thenar atrophy, and a positive Tinel and/or Phalen sign. It is caused by median nerve compression at the transverse carpal ligament.

Answer 60

keratinocytes in the basal layer of the epidermis or hair follicle. They most commonly occur on the face and often appear as pearly or translucent, pink or skin colored papules with central telangiectatic vessels

Answer 61

hereditary nonpolyposis colon cancer (HNPCC), or lynch syndrome, leads to occurence of colonic adenocarcinomas at a young age (age <50) along with predisposition for extraintestinal malignancies. Mutations of DNA mismatch repair genes (msh2, mlh1, msh6, pms2) are responsible for HNPCC. associated with colorectal, endometrial and ovarian cancers

Answer 62

mixed primary respiratory alkalosis and primary anion gap metabolic acidosis. mixed acid base distrubances can be recognized by inappropiate secondary compensation for one of the primary disturbances, indicating that an additional primary disturbance must be present.

Answer 63

brain herniation causes abnormal posturing due to disruption of descending motor tracts (rubrospinal, vestibulospinal). damage above the level of the red nucleus (cerebral hemispheres, internal capsule) typically results in decorticate (flexor) posturing. damage at or below the red nucleus (midbrain to pons) results in decerebrate (extensor) posturing.

Answer 64

a yellowish eyelid papule or plaque containing lipid laden macrophages is most likely xanthelasma. Xanthelasma may occur in association with primary or secondary hyperlipidemia. Cholestatic conditions such as primary biliary cholangitis are a potential cause of hypercholesterolemia leading to xanthelasma

Answer 65

air trapping and hyperinflation; these patients breathe at higher baseline lung volumes (higher functional residual capacity). The volume of air in the lungs that is not respired (residual volume) increases substantially, as does the fraction of air in the lungs that is not involved in respiration (residual volume/total lung capacity ratio)

Answer 66

causes a crescendo-decrescendo systolic murmur (best heard at the left sternal border) and delays closure of the pulmonic valve, resulting in widened splitting of S2. Inspiration increases blood flow to the right side of the heart, causing increased intensity of the murmur and even later closure of the pulmonic valve

Answer 67

thrombocytopenia and should be suspected in patients with ecchymoses, petechiae, mucosal bleeding, and no other obvious causes of thrombocytopenia (meds, bone marrow failure)

Answer 68

47, XXY causes infertility characterized by primary hypogonadism (elevated FSH and LH, low testosterone) and azoospermia. Other findings: long lower extremities, small, firm testes, and gynecomastia

Answer 69

The breast milk content of vitamins D and K is typically insufficient for the nutritional needs of the newborn. Vitamin K is given parenterally to all newborns at birth to prevent hemorrhagic disease of the newborn. Exclusively breastfed infants require vitamin D supplementation due to lack of sunlight exposure and to prevent rickets

Answer 70

The gastroduodenal artery lies along the posterior wall of the duodenal bulb and is likely to be eroded by posterior duodenal ulcers. Ulceration into the gastroduodenal artery can be a source of life-threatening hemorrhage

Answer 71

bacterial vaginosis causes a thin, gray or clear, malodorous discharge from overgrowth of anerobes (gardnerella vaginalis) and a loss of lactobacilli in the vaginal flora. Diagnosis is confirmed by the presence of clue cells and a positive amine whiff test with potassium hydroxide. Treatment is with clindamycin or metronidazole

Answer 72

deficiency of vitamin C, a water soluble vitamin, results in impaired collagen production. Manifestations include cutaneous findings of coiled hair and perifollicular keratosis, in addition to hemorrhagic complications such as gingival bleeding and easy bruising. PT, PTT, and platelet count are normal.

Answer 73

Cushing syndrome can be categorized as ACTH-dependent or ACTH-independent. Excess ACTH secretion in ACTH dependent Cushing syndrome leads to hyperpigmentation. In addition to increased cortisol production, ACTH stimulates production of adrenal androgens (testosterone, dehydroepiandrosterone sulfate) leading to hirsutism and menstrual irregularities

Answer 74

acute tubular necrosis with vacuolar degeneration and ballooning of the proximal tubular cells. Typical clinical findings include altered mentation, renal failure, high anion gap metabolic acidosis, increased osmolar gap, and calcium oxalate crystals in the urine.

Answer 75

mixed primary respiratory alkalosis and anion gap metabolic acidosis. Sodium bicarbonate facilitates conversion to the lipophobic, ionized form of salicylate (Sal-), which traps much of the compound in the bloodstream and increases its urinary excretion