Uworld Sim 1

Question 1

ARDS

Answer 1

characterized by hypoxemia and bilateral pulmonary edema in the absence of heart failure

most common in patients with severe systemic illness, trauma, or pulmonary injury

injury to alveolar pneumocytes and pulmonary endothelium leads to an inflammatory response resulting in increased capillary permeability, intraalveolar fluid accumulation, and hyaline membrane formation

Question 2

diabetic nephropathy

Answer 2

occurs 10-15 years after diagnosis

characterized by mesangial expansion, glomerular basement membrane thickening, and glomerular sclerosis

if the sclerosis is nodular, it is described as a Kimmelstiel Wilson lesion

Question 3

cardiac conduction system

Answer 3

fastest: bundle of His

slowest in the AV node and fastest in the Purkinje system

conduction speed of atrial muscle is higher than that of ventricular muscle

fastest: Purkinje>Atrial muscle>ventricular muscle>AV node

Question 4

osteosarcoma

Answer 4

bone tumor most often associated with Paget’s disease, arising in the femur, tibia, humerus, and other bones

destruction of the normal trabecular bone pattern, mixed radiodense and radiolucent areas, periosteal new bone formation, lifting of the cortex, and Codman’s triangle.

Question 5

globus sensation

Answer 5

common abnormal sensation of a foreign body, tightness, or fullness in the throat

often worse when swallowing saliva and may be alleviated with food or liquid

functional disorder of the esophagus associated with anxiety

Question 6

endometriosis

Answer 6

old blood collections cause chocolate cyst

biopsy: endometrial glands and stroma

early menarche, shorter menstrual cycles, and longer days of menstrual flow

dysmenorrhea manifests after menstrual cycles and leads to infertility, significant pelvic pain, deep dyspareunia

tx: NSAIDs and hormonal contraceptives, laparoscopy last resort

Question 7

vitamin A

Answer 7

not indicated in pregnancy; fat soluble vitamin that poses a toxicity risk

accumulates within stellate cells of the liver and not readily excreted in urine

teratogen during organogenesis: leads to spontaneous abortion and fetal defects

Question 8

DNA laddering

Answer 8

sensitive indicator of apoptosis that occurs when regulating factors (interleukins) withdrawn from proliferating cells

arises from the action of specific endonucleases during karyorrhexis

cleave DNA at internucleosomal linker regions which occur at 180 base pair intervals in the genome

Question 9

why do benzos lead to longer symptoms in the elderly?

Answer 9

elderly people have an increased volume of distribution secondary to decreased total body water, decreased total body mass, increased body fat, reduced liver size and blood flow

leads to increased side effects such as confusion, paradoxical agitation, anterograde amnesia, psychomotor retardation, ataxia, weakness, vertigo, syncope

Question 10

anticholinergic syndrome

Answer 10

fever, dry skin and mucous membranes, flushing, mydriasis and cycloplegia, altered mental status

caused by jimson weed

Question 11

germline mosaicisim

Answer 11

presence of multiple, genetically different cell lines within the body

the earlier the mutation occurs, the more daughter cells that are affected

achondroplasia

Question 12

diabetes mellitus complications

Answer 12

careful and regular inspection of feet for diabetic foot infections

Question 13

acute promyelocytic leukemia

Answer 13

young adult: fever, fatiguability, and sore throat

unresponsive to antibiotic treatment

on histo, large blast cells with auer rods azurophilic, needleshaped crytoplasmic inclusion formed by the fusion of primary granules

t(15;17) chromosomal translocation involving the retinoic acid receptor-alpha gene on chromosome 17 and the promyelocytic leukemia gene on chromosome 15

complications of pancytopenia and DIC

tx: all trans retinoic acid should be started ASAP

Question 14

cadherins

Answer 14

adhesion molecules that bind epithelial cells together within tissues

transmembrane proteins that interact intracellularly with intermediate proteins which facilitate binding to intermediate filaments or microfilaments within the cytoplasm

Ca2+ dependent

Question 15

molluscum contagiosum

Answer 15

32 y/o woman due to spots on her face for 3w eeks that are increasing in size and becoming more numerous

mildly pruritic, no pain, no fever, multiple papular lesions noted on trunk and face

MC: firm, flesh colored papules on the skin and mucous membranes with umbilicated centers

poxvirus; transmitted thru direct contact or fomites

epidermal hyperplasia with molluscum bodies, large eosinophilic cytoplasmic inclusions made of virus particles

Question 16

gallbladder release

Answer 16

delivery of acidic chyme from the stomach to the duodenum triggers bile release and stimulates S cell sin the crypts of Lieberkuhn to release secretin into systemic circulation

pancreas is then prompted by secretin to generate HCO3 rich fluid which neutralizes the hydrogen ions in chyme`

Question 17

knee dislocation

Answer 17

neurovascular examination distal to the point of dislocation is necessary because the popliteal artery, tibial nerve, and common peroneal nerve

popliteal artery is at high risk because it is deep in the popliteal fossa, close to the articular surface of the joint

politeal artery is especially sensitive to traction forces

Question 18

postpartum endometritis

Answer 18

polymicrobial uterine infection that is especially common after c section

sx: fever, lower abdominal pain, malodorous lochia, uterine tenderness and leukocytosis

cervix is a portal of entry but is not the affected organ

Question 19

varicella zoster

Answer 19

usually occurs in people over 50 can occur in kids if herpes zoster infection at <1 y/o

Question 20

sublimation

Answer 20

patients channel impulses into socially acceptable behaviors

Question 21

Her2/neu has intrinsic tyrosine kinase activity. What is the immediate effect of ligand binding to this receptor?

Answer 21

transduce signals from hormones such as insulin, EGF, PDGF, VEGF

transmembrane proteins that have a ligand binding extracellular region, hydrophobic transmembrane region, intracellular domain with inducible tyrosine kinase activity

ligand binding causes dimerization of 2 identical receptor subunits

each phosphorylates the other to expose the catalytic omain

Question 22

reflection

Answer 22

facilitating interview technique in which the physician repeats what the patient has said either word for word or by paraphrasing

allows the patient to feel heard and understand and strengthen the physician-patient relationship

obstructing interventions decrease spontaneous communication and are not helpful in promotting discussion

Question 23

cocaine abuse

Answer 23

vasoncstriction, impaired cell mediated immunity, reduced mucociliary clearance

presents as headaches, chronic nasal discharge, atrophic nasal mucosa, and perforation of the nasal septum

Question 24

heminephrectomy

Answer 24

acute reduction of the total GFR by 50%, the nephrons undergo significant structural and hemodynamic adaptations to allow for the single nephron GFR to rise. end result is to approximately 80% of 2 kidney GFR

Question 25

sildenafil

Answer 25

selective PDE5 inhibitor

PDE5 inhibition leads to augmentation of intracellular cGMP concentrations which mediates relaxation in teh smooth muscle cells that surround the cavernous venous sinuses of the corpora cavernosa

Question 26

craniopharyngiomas

Answer 26

slow growing suprasellar tumors arising from remnants of Rathke’s pouch

bimodal age distribution

patients present insidiously with headaches, pituitary dysfunction, visual disturbances

bitemporal hemianopia can occur and a calcified mass is uually foudn in the suprasellar region

Question 27

serratus anterior paralysis

Answer 27

originates on the 1st 8 ribs and inserts on the medial scapula

stabilizes and pulls the scapula upward to allow complete abduction of the arm over the head

paralysis results in in ability to raise the arm over the head and protrusion of the medial border of the scapula when the outstretched arm is pushed forward against resistance

innervation: long thoracic nerve

Question 28

exocrine pancreas

Answer 28

secretes approximately 1L of fluid which consists of an aqueous portion an enzymatic portion and the ductal cells

contain fixed concentrations of sodium and potassium that are virtually identical to those of plasma

HCO3 and Cl- vary with the pancreatic flow rate, which increases in response to secretin

high flow: HCO3 increases which Cl dros and its opposite at low flow

Question 29

schizophreniform disorder

Answer 29

2 month history of psychotic symptoms and negative symptoms

Question 30

HSV encephalitis

Answer 30

pathogenesis: HSV1–> olfactory tract–>olfactory cortex
presentation: fever, headache, seizures, aphasia, mental status
diagnosis: temporal lobe hemorrhage and edema
tx: IV acyclovir

Question 31

acute intermittent porphyria

Answer 31

autosomal dominant defect in PBG deaminase that can lead to elevated levels of PBG and ALA

sx: acute severe abdominal pain, nausea and vomiting, motor/sensory neuropathy, and neuropsychiatric manifestations

port wine colored urine that darkens on exposure to light and air

skin and photosensitivity are absent and patients are symptom free

Question 32

cobalamin deficiency

Answer 32

confusion, irritability, shock like sensation that radiates to his feet on neck flexion

long history of alcohol abuse with acute pancreatitis

low blood sugar

decreased vibratory sensation over the feet and ankles

Question 33

myasthenia gravis

Answer 33

usually young patient, autoantibodies against acetylcholine receptors at motor endplate of postsynaptic membrane of NMJ

thymic hyperplasia and thymoma

fluctuating and fatigable proximal muscle weakness; worse later in the day: ocular, bulbar, respiratory muscles

diplopia, bulbar muscle weakness, and ptosis on examination

Question 34

thymic hyperplasia

Answer 34

thymus is thought to the site of autoimmunization in MG and contains muscle like cells that express AChRs

leads to a decrease in the number of functional AChRs with resultant fatigable musculoskeletal weakness

Question 35

retinoblastoma

Answer 35

both copies of the RB1 gene must be lost for tumorigenesis to occur

reflects the 2 hit hypothesis

sporadic retinoblastoma develop 2 spontaneous somatic mutations in a single retinal cell resulting in a unilateral tumor

familial: born with a germline defect in one of their RB1 genes. All cells have hit their first hit required for tumor formation–> leads o bilateral and multifocal retinoblastoma, as well as osteosarcoma

Question 36

DiGeorge syndrome

Answer 36

chromosome 22q11.2 deletion; defective development of third and fourth pharyngeal pouches (predecessors of thymus, parathyroid gland, and ultimobranchial body)

conotruncal cardiac defects, abnormal facies, thymic hypoplasia, craniofacial deformities, hypocalcemia/hypoparathyroidism

impaired T cell immunity and tetanus

susceptible to recurrent viral, bacterial and fungal infections such as candida and pneumocystis jiroveci

Question 37

metabolic derangements in DKA

Answer 37

metabolic acidosis

ketonemia

ketonuria

hyperglycemia/glycosuria

hyponatremia

hypovolemia

hyperkalemia (due to increased K+/H+ and because insulin’s tendency to drive K+ into cells is missing)

total K+ are actually depleted due to urinary losses and GI losses

increased K+, increased glucose, decreased Na+

Question 38

chiari I malformation

Answer 38

most common and mildest form of chiari malformations

defects in craniocervical and hindbrain development that results in downward displacement of cerebellar structures that are often associated with a small posterior fossa

occipital headache due to meningeal irritation and cerebellar dysfunction due to compression of the cerebellar tonsils

downward displacement of the elongated cerebellar tonsils through the foramen magnum and into the upper cervical canal

Question 39

complete androgen insensitivity syndrome

Answer 39

rare X linked disorder for individuals with 46, XY karyotype with a female phenotype due to mutated testosterone receptors throughout the body

cryptorchid testes secrete testosterone and are located in the abdomen, inguinal canal, or labia majora

circulating testosterone is peripherally converted into estradiol to result in breast development

vagina ends abruptly in a blind pouch and Mullerian structures are absent as AMH stimulates regression of the Mullerian ducts

Question 40

premature infants

Answer 40

at significant risk for intraventricular hemorrhage or germinal matrix hemorrhage

germinal matrix: dense cellular and vascular layer of the subependymal zone of the brain from which neurons and glial cells devleop in utero; begins to involute at 28 weeks gestation and absent by term

begins betweent he caudate nucleus and thalamus, extends into the lateral, third, and fourth ventricles—>hydrocephalus

primary risk factor: physiologic immaturiry, infants with very low birth weight and those born preterm are at the greatest risk

Question 41

ototoxicity

Answer 41

caused by cisplatin; damages apical stereocilia within the Organ of Corti of the cochlear emmbranous labyrinth

Question 42

amiodarone

Answer 42

in some patients can result in interstitial pneumonitis that presents with slowly progressive dyspnea and nonproductive cough

fever, dyspnea, cough, dry inspiratory crackles, patchy interstitial

reversible with reduction in dose or discontinuation of the drug

other AE: arrhythmias, hepatic injury, thyroid abnormalities and bluish gray skin discoloartion

ILD meds also include nitrofurantoin, methotrexate, and bleomycin

Question 43

misoprostol

Answer 43

PGE1 analog that can be used to help prevent and treat NSAID induced peptic ulcers

NSAIDs inhibit COX1 and decrease PGE1 secretion, leading to decreased parietal cell acid secretion and no protection from acidic juices

Question 44

aspirin induced airway disease

Answer 44

10% of people with asthma develop nasal congestion or bronchospasm after ingesting aspirin or nonsteroidal anti inflammatory drugs

result from dysregulation of AA metabolism due to COX inhibition

increases flow dow the 5-LO pathway and reduces inhibition of the pathway via PGE2 leads to increased formatino of bronchoconstrictive leukotrienes

tx: montelukast

Question 45

HNSCC

Answer 45

strongly associated with the use of tobacco and alcohol

develop in the oral cavity with the ventral tongue, floor of the mouth, lower lip, soft palate and gingiva

infiltrates adjacent tissue and may eventually metastasize locally to lymph nodes or distally to mediastinal lymph nodes, lungs, liver, or bones

Question 46

Marfan syndrome

Answer 46

autosomal dominant connective tissue disease the classically affects the CV and MSK systems as well as the eyes

muation in FBN1 which codes for a connective tissue protein responsible for the production and maintenance of elastic fibers

difference in phenotype is observed even among those who carry the same genetic mutation in variable expressivity

Question 47

nitrates

Answer 47

direct vascular smooth muscle relaxation which causes systemic venodilation and decreased peripheral venous return–>EDV and pressure (decreased preload) which decreased myocardial oxygen demand by decreasing systolic wall stress

modest reduction in afterload due to systemic arterial vasodilation which further reduces left ventricular wall stress and myocardial oxygen demand

don’t affect cardiac chronotropy or inotropy but drop in systolic blood pressure typically leads to reflex tachycardia

Question 48

cystic fibrosis

Answer 48

autosomal recessive

mutations cause dysfunction of epithelial chloride channel resulting in impaired electrolyte transport by exocrine glands

function varies from tissue to tisstue

eccrine: CFTR acts to reabsorb chloride from sweat fluid and also enhances sodium reabsorption by the epithelial sodium channel due to higher levels of sodium and chloride

intestinal and respiratory epithelium: CFTR normally secretes chloride into the lumen and has an inhibitory effect on ENaC

Question 49

allelic heterogeneity

Answer 49

instances when different mutations at the same genetic locus causes similar phenotypes

ex: B thalassemia

presentations are similar but the exact phenotype can vary

Question 50

hereditary hemochromatosis

Answer 50

autosomal recessive disease characterized by excessive GI absorption of Fe3+

store iron in the form of hemosiderin within the dermis and various parenchymal organs

typically silent in early adulthood, presenting only after significant amounts have accumulated (>40 y/o)

presents depending on what tissues the iron is being stored in and skin hyperpigmentation is also commonly seen, mild hepatomegaly, and atrophic testes

Question 51

hepatic cirrhosis

Answer 51

irreversible process due to chronic injury to the hepatic parenchyma

hepatic necrosis and extensive fibrosis cause distortion of the hepatic vascular bed with formation of disorganized regenerative nodules

disruption of hepatic vasculature causes portal hypertension leading to portosystemic anastomoses and ascites

portal venous system is valveless therefore portal hypertension can cause retrograde flow of portal blood away from the liver and increased pressure within the splenic vein

leads to congestion of splenic red pulp and result sin splenomegaly

Question 52

indirect ELISA

Answer 52

identifies the presence of serum antibody directed against a known target antigen

1. known antigen is fixed to the surface of a well.
2. patient’s serum is added and then the plate is washed.
3. anti-human immunoglobulin antibody coupled to a substrate modifying enzyme is then added. This binds and the plate is then washed again.
4. a substrate is added to elicit a signal. If quantitative, the intensity of color change is proportional to the amount of antibody present

Question 53

impetigo

Answer 53

prolonged erythema and a yellow crust on a cutaneous wound

most common causes: staph aureus and strep pyogenes

Question 54

efflux pumps

Answer 54

transport proteins that excrete toxic substances like Abs from cytoplasm/periplasm of bacteria into the external environment

energy dependent and use ATP, sodium gradients, or proton electrochemical gradients to pump H+ out leading to a transmembrane pH gradient of 2-3

high pH agars neutralize proton gradients by raising pH of external environment and limiting the H+ concentration difference between the exterior and interior of the cell

reduction in ciprofloxacin MIC with a high pH agar indicates that the underlying source of resistance was an efflux pump

Question 55

achondroplasia

Answer 55

autosomal dominant disorder caused by a gain of function point mutation on FGFR3 gene which normally acts to inhibit excessive cartilage proliferation in the long bones

becomes const activated, leading to severely restricted chondrocyte proliferation in growth plate cartilage and decreased endochondral ossification

90% are denovo, 10% are inherited from affected parent

physical sx: rhizomelia, brachydactyly in a trident configuration, macrocephaly, midface hypoplasia, frontal bossing

increased risk of spinal stenosis andr resultant nerve compression which presents with proximal lower extremity weakness and paresthesia

Question 56

maple syrup urine disease

Answer 56

characterized by a defect in the branched chain alpha keto acid dehydrogenase complex resulting in an inability to degrade branched chain alpha amino acids (leucine, isoleucine, and valine) and their alpha ketoacid metabolites

causes BCAAs and a-ketoacids to accumulate in the plasma and urine which cause CNS toxicity

early symptoms: poor feeding and vomiting

a-ketoacid dehydrogenase requires thiamine (b1) as a cofactor (transketolase does as well)

Question 57

hydrops fetalis

Answer 57

due to alpha thalassemia major and loss of all 4 alpha globin genes and formation of hemoglobin barts (4 gamma chains)

extreme affinity for oxygen (>10x HgA) and unable to release O2 to the tissues

leads to this condition which is characterized by anasarca, ascites, pleural/pericardial effusions and intrauterine death

Question 58

androgen binding protein

Answer 58

synthesized by sertoli cells in response to FSH and secreted into the seminiferous tubule lumen

normal circulating testosterone levels suggests normal HPG axis and normal secretory function of Leydig cells but low concentration of T in the seminiferous tubules suggests sertoli cell dysfunction

Question 59

pulmonary embolism

Answer 59

causes V/Q mismatch that increases ventilation and heart rate via a chemoreceptor reflex

resulting hyperventilation lowers arterial CO2 but is unable to compensate fully for the hypoxemia. HIghly ventilated regions can excrete more Co2 to compensate. Hyperventilation results in hypocapnia and respiratory alkalosis with high pH

Question 60

costosternal syndrome

Answer 60

occurs after repetitive activity and involves the upper costal cartilage at the costochondral or costosternal junctions

pain is typically reproduced with palpation and worsened with movement or changes in position

patients do not have palpable warmth, swelling, or erythema

Question 61

verapamil

Answer 61

non DHP calacium channel blocker that works by blocking L type Ca2+ channels, which prevents the initial calcium influx into cardiac myocytes and vascular smooth muscle cells

skeletal muscle is not dependent on extracellular calsium influx and there fore Ca channel blockers don’t affect skeletal muscle contractility

Question 62

RRR

Answer 62

(absolute risk control-absolute risk treatment)/absolute risk control