Uworld 6

Question 1

Benign prostatic hyperplasia leads to?

Answer 1

Leads to progressive bladder outlet obstruction. Over time, increased urinary pressures can cause hydronephrosis and renal parenchymal atrophy with scarring. This can progress to chronic kidney disease.

Question 2

What are transverse tubules (T-tubules)?

Answer 2

Invaginations of the sarcolemma that transmit depolarization signals to the sarcoplasmic reticulum to trigger the release of calcium and induce muscle contraction.

The uniform distribution of T-tubules in striated muscle fibers ensures that each myofibril contracts at the same time, which is necessary for efficient contraction.

Question 3

Hypertrophic cardiomyopathy is caused by?

Answer 3

Genetic mutations affecting structural proteins of cardiac sarcomeres (eg, beta myosin heavy chain, myosin-binding protein C) and is one of the most common causes of sudden cardiac death in young adults.

Question 4

Congenital diaphragmatic hernia (herniation of abdominal contents into the thorax) causes?

Answer 4

Hypoplasia from compression of the lungs.

Neonates present with respiratory distress shortly after birth.

Question 4

What is seen on histo for hypertrophic cardiomyopathy?

Answer 4

cardiomyocyte hypertrophy with haphazard cellular arrangement and interstitial fibrosis

Question 5

What is seen on x-ray for congenital diaphragmatic hernia?

Answer 5

thoracic bowel loops; the distal end of a feeding tube may also be seen within the thorax

Question 6

Long-standing rheumatoid arthritis can affect what?

Answer 6

Can affect the cervical spine, causing vertebral malalignment (subluxation) that can affect the atlantoaxial joint.

Extension of the neck during endotrachael intubation can worsen the subluxation, leading to acute compression of the spinal cord and/or vertebral arteries.

Question 7

Which HIV drug is associated with HLA-B*57:01?

Answer 7

Abacavir

Question 8

What is Rett syndrome?

Answer 8

a genetic disorder characterized by normal development until age 6-18 months, when regression of speech, loss of purposeful hand movements, development of sterotypical movements, and gait abnormalities occur.

Neutropathology shows arrested brain development rather than neurodegeneration.

Question 8

Cholecystokinin (CCK) stimulates what?

Answer 8

The release of cholecystokinin from the duodenum and jejunum after exposure to fat and protein rich meals stimulates gallbladder contraction.

In patients with gallstones or biliary sludge, contraction can force the stones/sludge against the gallbladder outlet, causing temporary occlusion of outflow and increased intragallbladder pressure. This manifests as postprandial upper abdominal pain that waxes and wanes with CCK levels (biliary colic).

Question 9

The gag reflex is mediated by?

Answer 9

afferents from glossopharyngeal nerve (CN IX) and efferents from the vagus nerve (CN X)

Question 10

An absent gag reflex may indicate dysfunction of what?

Answer 10

Medulla oblongata.

Question 11

Fat embolism syndrome should be suspected in what kind of patients?

Answer 11

Patient with severe long bone and/or pelvic fractures who develops acute-onset neurologic abnormalities, hypoxemia, and a petechial rash.

Occlusion of the pulmonary microvessels by fat globules is an early histo finding

Question 12

What are symptoms of lead poisoning?

Answer 12

Lead poisoning in adults typically occurs through occupational exposure.

Symptoms: colicky abdominal pain, constipation, lead lines on the gum, peripheral neuropathy and amenia

Question 13

What are labs for lead poisoning?

Answer 13

Microcytic anemia with normal iron studies and peripheral blood smear may reveal basophilic stippling

Question 14

Ethanol inhibits what?

Answer 14

Inhibits gluconeogenesis and can cause hypoglycemia once hepatic glycogen stores are depleted.

Question 15

Classic 21-hydroxylase deficiency causes?

Answer 15

decreased cortisol and aldosterone production with increased adrenal androgen production

Question 16

Classic 21-hydroxylase deficiency causes what in boys?

Answer 16

presents 1-2 weeks after birth with vomiting, hypotension, hyponatremia, and hyperkalemia due to salt wasting; genitalia are normal

Question 17

Classic 21-hydroxylase deficiency presents how in girls?

Answer 17

presents at birth with ambiguous genitalia

Question 18

Traits of blastomyces dermatitdis

Answer 18

dimorphic fungus seen in tissue as round or oval yeasts with thick walls and broad based budding

Endemic in southeastern US (states east of Mississippi River)

Lungs are primary site of involvement, and the skin and bone are the major sites of dissemination

Question 19

MOA of raltegravir

Answer 19

an integrase inhibitor that disrupts HIV genome integration, preventing synthesis of viral mRNA

Question 20

What is necessary to induce viral HIV gene expression?

Answer 20

Integration of double-stranded HIV DNA into the host cell’s chromosomes is necessary to induce viral gene expression and prevent degradation of the viral genome.

Question 21

Hypovolemia triggers a variety of compensatory mechanisms to improve tissue perfusion. These include:

Answer 21

-activation of the renin-angiotensin-aldosterone system (resulting in increased aldosterone and endothelin release)

-increased vasopressin release

-increased sympathetic tone

Question 22

What are most common side effects of aspirin?

Answer 22

GI mucosal injury and bleeding.

These are due primarily to cyclooxygenase-1 inhibition, which results in impaired prostaglandin-dependent GI mucosal defense and decreased platelet aggregation.

Question 23

What is bullous pemphigoid?

Answer 23

Autoimmune blistering disease that typically occurs in patients >60 It presents with tense bullae with rare mucosal involvement. Autoantibodies against hemidesmosomes create subepidermal cleavage.

Question 24

What is seen on immunofluorescence for bullous pemphigoid?

Answer 24

liner deposition of IgG and/or C3 along the basement membrane

Question 25

Intracranial pressure can be temporarily reduced with what?

Answer 25

intravenous mannitol, an osmotically active agent that increases plasma oncotic pressure, causing water from the interstitial space to be drawn into the vascular compartment. In some patients (eg, history of heart failure, low left ventricular reserve function), rapidly increased intravascular volume can cause pulmonary edema by abruptly increasing pulmonary capillary hydrostatic pressure.

Question 26

What are chromaffin cells?

Answer 26

Modified neuroendocrine cells derived from the neural crest

Question 27

Chromaffin cells in the adrenal medulla are stimulated by?

Answer 27

Acetylcholine released by sympathetic preganglionic neurons and secrete catecholamines directly into the bloodstream to amplify sympathetic nervous system activity

Question 28

Communicating hydroceles and indirect inguinal hernias are caused by?

Answer 28

An incomplete obliteration of the processus vaginalis. The resultant connection between the scrotum and abdominal cavity can allow for fluid leakage (hydrocele) or the passage of abdominal contents (indirect inguinal hernia)

Question 29

What is heard on ausculation for aortic regurgitation?

Answer 29

High pitched, diastolic murmur with a decrescendo intensity pattern

Question 30

Where is the murmur of aortic regurgitation due to aortic root dilation best heard at?

Answer 30

At the right upper sternal border

Question 31

Where is the murmur of aortic regurgitation due to valvular pathology best heard at?

Answer 31

At the 3rd intercostal space

Question 32

How is a premature ventricular contraction seen on ECG?

Answer 32

wide QRS complex, opposite-facing T wave, and brief ensuing sinus pause Left ventricular filling is less than normal at the time of the PVC The ensuring sinus pause allows for greater than normal filling during the post-PVC beat

Question 33

What is the most common primary immune deficiency?

Answer 33

Selective IgA deficiency

Question 34

How does selective IgA def present?

Answer 34

Recurrent sinopulmonary and gastrointestinal infections as well as autoimmune disease Patients with severe IgA def can have anaphylaxis during transfusion of blood products that contain small amounts of IgA

Question 35

What is seen in Kawasaki disease?

Answer 35

Vasculitis characterized by fever for >5 days and >4 of the following: nonexudative conjunctivitis, extremity changes, cervical lymphadenopathy, mucositis, and polymorphous rash

Question 36

Alpha-1 antitrypsin def can cause?

Answer 36

Can induce early onset emphysema, which is further accelerated by smoking

Question 37

What is emphysema?

Answer 37

Characterized by expiratory airflow obstruction (decreased FEV1/FVC ratio), airspace enlargement and hyperinflation (increased total lung capacity), and a decreased diffusing capacity due to loss of alveolar surface area

Question 38

MOA of statins

Answer 38

Statins inhibit the intracellular rate-limiting step of cholesterol biosynthesis via competitive inhibition of HMG-CoA reductase. This leads to enhanced hepatic LDL receptor recycling and increased LDL clearance from the circulation.

Question 39

What is the most common complication of statin use?

Answer 39

Statin-induced myopathy (eg, myalgia, elevated creatine kinase)

Question 40

What are the levels in exogenous thryrotoxicosis?

Answer 40

Radioactive iodine uptake and serum thyroglobulin level are low, indicating suppression of endogenous thyroid metabolic activity Serum T3 are often elevated.

Question 41

What happens to the liver in right-sided heart failure?

Answer 41

Congestive hepatopathy is a common complication of right-sided heart failure. Patchy hemorrhage and necrosis predominantly affect the centrilobular regions (zone 3) where hepatic congestion is most prominent. The centrilobular necrosis, combined with relatively normal appearing periportal regions (zone 1), creates an overall heterogenous appearance sometimes referred to as "nutmeg liver"

Question 42

Illnesses that result in cold agglutinin formation

Answer 42

Mycoplasma pneumoniae Infectious mononucleosis Infection with mycoplasma pneumonia can result in the formation of cold agglutinins, which are IgM antibodies (primarily) that bind red blood cells and cause clumping/agglutinations at low body temperatures

Question 43

Maple syrup urine disease is caused by a deficiency of?

Answer 43

Branched-chain alpha-keto acid dehydrogenase, an enzyme that requires several coenzymes (thiamine, lipoate, coenzymes A, FAD, NAD) to metabolize branched chain amino acids Some patients with milder forms of MSUD improve with high dose thiamine treatment.

Question 44

Pelvic splanchnic nerves S2-S4 innervate what?

Answer 44

Provide parasympathetic innervation to the bowel and bladder

Question 45

What is cauda equina syndrome?

Answer 45

Impairment of S2-S4 = constipation and difficulty urinating Radicular low back pain and leg weakness (sciatic nerve) and saddle anesthesia (pudendal, ilioinguinal nerves)

Question 46

Untreated cervicitis can progress to what?

Answer 46

Pelvic inflammatory disease and long term complications such as tubal factor infertility and ectopic pregnancy Neisseria gonorrhoeae and Chlamydia trachomatis can cause acute cervicitis (eg purulent cervical discharge, friable cervix)

Question 47

Occlusion of the portal triad can be used to distinguish the source of RUQ bleeding. If the bleeding subsides following occlusion, the source is likely to be?

Answer 47

The hepatic artery or portal vein

Question 48

Occlusion of the portal triad can be used to distinguish the source of RUQ bleeding. If the bleeding persists after occlusion, what is injured?

Answer 48

Inferior vena cava or hepatic veins.

Question 49

MOA of mycophenolate

Answer 49

An immunosuppression drug that inhibits inosine 5'-monophosphate dehydrogenase in the de novo purine synthesis pathway. It provides relatively specific suppression of lymphocyte proliferation, largely because activated lymphocytes lack an established purine salvage pathway that is present in other hematopoietic cell lines

Question 50

What is the most common primary cardiac neoplasm?

Answer 50

Myxomas usually in the left atrium

Question 51

How does myxomas present?

Answer 51

The tumors typically cause position-dependent obstruction of the mitral valve, leading to a mid-diastolic murmur and symptoms of decreased cardiac output (eg, dyspnea, syncope) Constitutional symptoms (eg fever, weight loss) may also be present.

Question 52

How does myxomas look on histo?

Answer 52

Scattered cells within a mucopolysaccharide stroma and blood vessels with hemorrhage

Question 53

What are the key findings in Edwards Syndrome (trisomy 18)?

Answer 53

fetal growth retardation, hypertonia (clenched hands with overlapping fingers), rocker bottom feet, and cardiac/GI/renal issues

Question 54

Edwards Syndrome (trisomy 18) is most commonly the result of?

Answer 54

Meiotic nondisjunction due to advanced maternal age

Question 55

Why is the right ventricle relatively protected from myocardial infarction and contractile function of the RV usually returns to normal following MI?

Answer 55

Relatively small muscle mass with high capacity to increased oxygen extraction, perfusion throughout the cardiac cycle, and heightened ischemic preconditioning.

Question 56

What is a melanoma derived from?

Answer 56

Melanoma is a malignancy of melanocytes, which are embryologically derived from neural crest cells.

Question 57

Where do neural crest cells originate from?

Answer 57

From the ectoderm and give rise to a diverse cell lineage, including neural ganglia (eg dorsal root ganglia, sympathetic/parasympathetic ganglia) and the adrenal medulla.

Question 58

Down Syndrome (trisomy 21) patients are increased risk for which hematologic malignancies?

Answer 58

Acute lymphoblastic leukemia and acute megakaryoblastic leukemia

Question 59

How does trochlear nerve palsy present?

Answer 59

Trochlear nerve palsy is typically traumatic or idiopathic. Presents: vertical diplopia that worsens when the affected eye looks down and toward the nose (eg walking downstairs, up-close reading) Patients compensate by tucking the chin and tilting the head away from the affected eye

Question 60

The trochlear nerve innervates what?

Answer 60

Superior oblique muscle, which causes the eye to intort (internally rotate) and depress while adducted

Question 61

Elevated levels of plasma homocysteine are an independent risk factor for?

Answer 61

Thrombotic events

Question 62

Homocysteine can be metabolized to?

Answer 62

Methionine, via remethylation or to cystathionine, via transsulfuration

Question 63

Hyperhomocysteinemia is most commonly due to what?

Answer 63

Genetic mutations in critical enzymes or def of vitamin B12, b6, and folate

Question 64

How does dofetilide and ibutilide (class III antiarrhythmics) used to treat atrial fibrillation?

Answer 64

By blocking the rapid component of the delated-rectifier potassium current to slow repolarization and increase the effective refractory period. As a result, the QT interval is prolonged, creating an increased risk of polymorphic ventricular tachycardia (torsade de pointes)

Question 65

What is the action of carbon dioxide on cerebral vasculature?

Answer 65

Carbon dioxide is a potent vasodilator of cerebral vasculature Tachypnea causes hypocapnia and cerebral vasoconstriction, thereby decreasing cerebral blood volume and intracranial pressure

Question 66

Anesthetics with high tissue solubility are characterized by?

Answer 66

Large arteriovenous concentration gradients and slower onsets of action. The arteriovenous concentration gradient reflects the overall tissue solubility of an anesthetic.

Question 67

What is kinesin?

Answer 67

A microtubule-associated, ATP powered motor protein that facilitates the anterograde transport of neurotransmitter-containing secretory vesicles down axons to synaptic terminals

Question 68

Right border of the heart on chest X-ray is formed by?

Answer 68

The right atrium. the right middle lobe is adjacent to the right border of the heart. Consolidation in the right middle lobe can obscure the xray silhoutette of the right heart border.

Question 69

Whar are the most common cause of subungual splinter hemorrhages?

Answer 69

Microemboli from the valvular vegetations of bacterial endocarditis are the most common cause of subungual splinter hemorrhages. The presence of these lesions necessitates careful cardiac auscultation to detect a possible new-onset regurgitant murmur.

Question 70

Selective vasoconstriction of the efferent arteriole (up to certain extent) increases what?

Answer 70

Hydrostatic pressure in the glomerular capillaries, and therefore increases the glomerular filtration rate. As efferent arteriolar constriction continues to increase, the glomerular filtration rate begins to decrease due to a flow-mediated rise in oncotic pressure in the glomerular capillaries. The filtration fraction always increases with increasing efferent arteriole constriction.

Question 71

Renal amyloidosis typically presents how?

Answer 71

With proteinuria and nephrotic syndrome. Diagnosis confirmed by kidney biopsy: apple-green birefringence with Congo red stain under polarized light Serum protein electrophoresis demonstrating a monoclonal protein helps establish the diagnosis of immunoglobulin light chain (AL) amyloidosis.

Question 72

Sirolimus MOA

Answer 72

binds to immunophilin FK binding protein (FKBP) in the cytoplasm, forming a complex that binds and inhibits mTOR (mammalian target of rapamycin). Inhibition of mTOR signaling blocks IL-2 signal transduction and prevents cell cycle progression and lymphocyte proliferation.

Question 73

Histo for small bowel mucosa in patients with primary lactase def

Answer 73

appears normal

Question 74

Traits of cryptococcus neoformans

Answer 74

Yeast with a thick polysaccharide capsule that is found primarily in soil contaminated by bird droppings. Inhalation of the pathogen into the lungs leads to asymptomatic primary infection usually followed by life-long latent infection. However, immunocompromised (eg, advanced AIDS) patients are at high risk for reactivation with spread to the CNS

Question 75

What is highly suggestive of mucormycosis?

Answer 75

Facial pain, headache, and a black necrotic eschar in the nasal cavity of a patient with diabetic ketoacidosis. The fungi show broad nonseptate hyphae with right angle branching. Txt: surgical debridement and antifungal therapy

Question 76

What are the physiologic changes for the cardiovascular in pregnancy?

Answer 76

During pregnancy, increased metabolic demands leads to multiple physiologic cardiovascular changes, including decreased systemic vascular resistance and increased blood volume, These changes increased preload and decreased afterload, resulting in increased stroke volume and cardiac output. Heart rate also gradually increases during pregnancy and is the major contributor to increased cardiac output in late pregnancy.

Question 77

Oligohydramnios (low amniotic fluid) is often associated with what?

Answer 77

kidney dysfunction in the fetus (eg, diffuse cysts seen in autosomal recessive polycystic in the fetus). Extrinsic fetal compression from a low amniotic fluid levels leads to Potter sequence with characteristic findings of flattened facies, limb deformities, and pulmonary hypoplasia.

Question 78

Paroxysmal nocturnal hemoglobinuria leads to the formation of what?

Answer 78

Formation of membrane attack complexes on erythrocytes. Treatment with monoclonal antibody against C5, the first component of the membrane attack complex, can improve symptoms. However, it also increases risk for encapsulated bacterial infection. Therefore, patients require vaccination and antibiotic prophylaxis against Neisseria meningitidis and Streptococcus pneumonia.

Question 79

What is a major limitation of single gene sequencing?

Answer 79

Single gene sequencing is the initial genetic test for suspected disorders most commonly caused by a mutation in a single gene, such as beta thalassemia trait. A major limitation is the detection of whole gene deletions because the primers used in gene sequencing require complementary sequences within the gene to bind.

Question 80

What are common asthma triggers?

Answer 80

Exercise, cold air, respiratiory infection, and exposure to inhaled allergens (eg, dust mites, cockroaches, pet dander, mold, pollen)

Question 81

What suggests asthma?

Answer 81

Intermittent respiratory symptoms in a patient with a normal chest x-ray, sputum eosinophils, and reduced FEV1 suggest asthma.

Question 82

What is the MOA of sulfonylureas (eg, glyburide, glimepiride)? AE?

Answer 82

Increase insulin secretion by pancreatic beta cells independent of blood glucose concentration. These meds have a high incidence of hypoglycemia, especially in the elderly population.

Question 83

Where does blood accumulate in a subgaleal hemorrhage?

Answer 83

Between the periosteum and galea aponeurosis presents with a diffuse, progressive, fluctuant scalp and neck swelling; massive blood loss can lead to shock and death if not promptly recognized.

Question 84

What is a subgaleal hemorrhage?

Answer 84

A potentially fatal neonatal bleed that occurs during delivery when emissary veins between the dural sinuses and scalp are sheared.

Question 85

Why does bone erosions occur in ankylosing spondylitis?

Answer 85

Bone erosions occur primarily in vertebral bodies; however, new bone formation typically occurs at the junction of the periosteal margin and adjacent cartilage, leading to bridging syndesmophytes and ankylosis. This causes spinal rigidity, postural alteration, and increased risk of fracture.

Question 86

What is ankylosing spondylitis?

Answer 86

An inflammatory spondyolarthropathy characterized by simultaneous erosion of bone and new bone formation.

Question 87

A number of changes occur in the liver with aging that can affect drug metabolism. Typical changes include?

Answer 87

-decreased liver mass and blood flow -decreased cytochrome P-450 expression and concentration -reduced hepatic regeneration after injury However, hepatic aminotransferase levels are unchanged.

Question 88

The most common indicator of obesity-related disease is?

Answer 88

A reduction in expiratory reserve volume and functional residual capacity, but forced expiratory volume in 1 second, forced vital capacity, and total lung capacity are also typically decreased.

Question 89

What can cause a pattern of extrinsic restrictive pulmonary function tests?

Answer 89

Obesity, particularly morbid, central obesity

Question 90

Case-fatality rate formula

Answer 90

dividing the number of fatal cases of a disease or condition by the total number of people with that disease or condition

Question 91

Mycobacterial resistance to isoniazid (INH) mediated by?

Answer 91

Primarily mediated by reductions in the catalase-peroxidase enzyme or through genetic modification of INH binding site on the mycolic acid synthesis enzyme

Question 92

What is minute ventilation?

Answer 92

Equal to the product of tidal volume and respiratory rate and includes dead space ventilation

Question 93

What alveolar ventilation?

Answer 93

Equal to the product of respiratory rate and the difference between tidal volume and dead space volume.

Question 94

MOA of digoxin

Answer 94

Directly inhibits the Na-K-ATPase pump in myocardial cells, leading to a decrease in sodium efflux and an increase in intracellular sodium. This reduces the forward activity of the sodium-calcium exchanger, causing increased intraceullar calcium concentration and improved myocyte contractility.

Question 95

What is Reye syndrome?

Answer 95

Should be suspected in a young child with acute liver failure and encephalopathy after receiving aspirin for a virus-induced fever. Can lead to hepatic steatosis, hyperammonemia, and diffuse astrocyte swelling (ie, cerebral edema)

Question 96

What is seen on IF for rapidly progressive glomerulonephritis?

Answer 96

Linear (ribbon-like) deposits of IgG and C3 along the GBM

Question 97

What antibodies is seen in rapidly progressive glomerulonephritis?

Answer 97

Anti-glomerular basement membrane (GBM) antibodies react with collagen type IV, causing rapidly progressive glomerulonephritis with glomerular crescent formation on light microscopy.

Question 98

What is the pathophysiology of neonatal hypoglycemia?

Answer 98

Neonatal hypoglycemia is common in infants of diabetic mothers. The pathophysiology involves maternal hyperglycemia, which in turn causes fetal hyperglycemia and compensatory hyperfunctioning of the pancreas (ie, hyperinsulinemia). After birth, persistently elevated insulin levels lead to transient hypoglycemia.