NBME Test #1 Flashcards
What is most important in maintaining blood pH near 7.4? What would change these values?
Most important = bicarbonate-carbonic acid buffer –> changes in ventilation impact the relationship of the buffer and are responsible for compensation for acid-base disturbances. Breathing in low PO2 = hyperventilation = less PCo2 = alkalosis
What is specificity? What decreases sensitivity?
Proportion of all people with the disease who test positive for the disease. Moving cut point higher decreases sensitivity?
What is M protein associated with? What are some other symptoms of this disease?
M spike most associated with multiple myeloma, which presents with bone pain, anemia, hypercalcemia, renal dysfunction, and lytic bone lesions
How does an AV Fistula impact pressures and cardiac output?
Increases right atrial pressure and increases cardiac output due to the increase in preload. AVF = abnormal artery/vein communication = low resistance and high volume flow
Characteristics of Pierre Robin Syndrom
Presents at birth with small jaw, downward displacement of tongue, celft palate –> can lead to airway obstruction, hypoxia, issues with feeding. Caused by defect in first pharyngeal arch
What develops from each pharyngeal arch?
First: maxilla, mandible, masseter, pterygoids, mylohyoid, CN V2 and V2
Second: Middle ear, hyoid bone, temporal styloid process, muscles including facial muscles, CN VII
Third: Stylopharyngeus muslce and glossopharyngeal nerve
Fourth: Cricothyroid and muscles of soft palate, thyroid
Sixth: All intrinsic muscles of larynx except cricothyroid
In mycobacterium tuberculosis, what is the virulence factor? How does it act?
Cord factor = glycolipid on surface of cell wall that protects the bacteria from phagocytic killing and is directly toxic to macrophages
What is Kaposi sarcoma? How does it present? What does biopsy show?
Low-grade neoplasm of vascular endothelial cells with raised, erythematous cutaneous plaques that are reddish-purple. On histology, see slit-like vascular spaces with proliferation of spindle cells and is usually caused by HHV-8.
What factor can increase cerebral blood flow?
Serum carbon dioxide directly increases/decreases cerebral blood flow: hypocapnia = cerebral vasoconstriction and hypercapnia = cerebral vasodilation. Changes in MAP have minimal impact on CBF.
What is the difference between Hunter and Hurler syndrome? What are they characterized by?
Both are mucopolysaccharidoses = enzyme deficiency
- Hurler caused by a-iduronidase and Hunter caused by iduronate-2 sulface resulting in heparan sulafe and dermatan sulface
Hurley = AR, first year of life, coarse facial features, corneal clouding, hepatosplenomgaly, joint contractures, developmental delay
Hunter = x linked recessive and milder, no corneal clouding
What test is used to test cerebellar dysfunction? What about other neuro tests? (Babinski, Dolls eye, Glabellar tap, tinel?)
Rapid alternating movements
Babinski: upper motor neuron sign for damage to corticospinal tract
Dolls eye: brainstem reflex
Glabellar tap: blinking from tapping –> primitive related to frontal lobe immaturity
Tinels: median nerve –> carpal tunnel
What is the typical presentation of sarcoidosis?
SOB and cough in a younger, african american female associated with uveitis, erythema nodosum, and bilateral hilar lymphadenopathy with noncaseating granulomas
What are classic physical exam findings associated with pleural effusion? How is this different from lobar pneumonia?
Unilateral decreased breath sounds, dullness to percussion, decreased tactile fremitus, in lobar pneumonia –> coughing, fever, chills, INCREASED tactile fremitus
Preventing polymerization of actin filaments would impact what function of leukocytes?
Phagocytosis –> permits extension of cell membrane around pathogen to allow for encapsulation and internalization
What is the pattern of sarcomeres in left ventricular hypertrophy? What about in dilated cardiomyopathy?
LVH: Increased sarcomeres in parallel with each other to generate grader contractile force to overcome higher afterload
Dilated cardiomyopathy: Increased sarcomeres in series - cardiac myofibrils lengthen
In pediatric patients, what is the difference between viral synovitis and septic arthritis?
Septic arthritis: trauma, bacteremia, fever, chills, myalgias, nausea, painful swollen joint with limited ROM, often knee and hip, leukocytosis, increased erythrocyte sedimentation rate and c-reactive protein
Viral synovitis: viral infection causes inflammation often in hip, but NO leukocytosis and only mildly elevated ESR and c-reative protein
What is fibronectin? What is its role?
Critical component of extracellular matrix that is secreted from cells into extracellular space
How does acute intermittent porphyria present? What accumulates? whats different in porphyria cutanea tarda?
Sx: psychosis, abdominal pain, burgundy urine following a medication exposure = acute intermittent porphyria
Mutations of enzyme porphobilinogen deaminse = can’t synthesize heme = accumulation of porphobilinogen which is neurotoxic. NO photosensitivity.
Porphyria cutanea tarda = Uroporphyrinogen decarboxylase and get cutaneous photosensitivity/blistering
What is the mechanism of metformin?
Decreases gluconeogenesis, increases glucose uptake, and decreases serum free fatty acid concentration. Side effects include nausea, abdominal discomfort, diarrhea and RARELY, but importantly, lactic acidosis.
What is the mechanism of erectile dysfunction meds? What is their name?
Phosphodiesterase inhibitors that directly relax smooth muscle of the vasculatore of corpora cavernosa which leads to erection. Work by overriding sympathetic input that usually vasoconstricts to extinguish erections.
What are the actions of the rotator cuff muscles?
Internal rotation: subscapularis
External rotation when adducted: teres minor
External rotation: infraspinatus
Abduction: supraspinatus
What helps with scar remodeling and wound healing?
Matrix metalloproteinases, which help breakdown extracellular matrix and breakdown of bone/cartilage. necessary for healing of wounds.
How does Vitamin E deficiency present?
Usually protects erythrocytes from free radical damage, so deficiency = hemolytic anemia and generalized muscle weakness, but NO megaloblastic anemia/hypersegmend neutrophils
What organisms cause cellulitis? How does it present?
Cutaneous erythema, warmth following inoculation from an injurty like an abrasion. Fever, tachycardia, leukocytosis.
Two most common pathogens: Staph Aureus and Streptococcus Pyogenes (Group A)
What is proliferative glomerulonephritis? How is this different from minimal change disease?
Presentation: Children, nephritis dynrome following acute pharyngitis, usually follows strep pyogenes.
Nephritic syndrome with gross/microscopic hematuria and RBC casts, as well as proteinuria.
Minimal change disease is most common NEPHROTIC syndrome in kids triggered by recent infection.
What is the mechanism of gemfibrozil and pioglitazone?
Pioglitazone: binds to peroxisome proliferator activated receptors (PPARs) = increased insulin sensitivity
Gemfibrozil = fibrate lipid lower agents that activates PPARs and up-regulates lipoprotein lipase = decreased LDL, increased HDL, decreased triglyceride concentrations
How do you access the renal arteries from the femoral artery? What does the celiac trunk, internal iliac arterys, and SMA supply?
Advance just superior to the testicular artery.
Celiac trunk: –> common hepatic, left gastric, splenic artery supplying liver, stomach, proximal duodenum, pancreas, inerior esophagus, and spleen
Internal Iliac arteries: Branches of common iliac –> buttocks and pelvic organs including bladder but NOT the kidneys
SMA: branch of abdominal aorta, supplies duodenum, jejunum, ileum, and proximal 2/3 of the colon
What vessel is involved in portal venous system and can lead to portal HTN? What is an outcome of portal HTN and how does this manifest?
Inferior esophageal vein drains into left gastric, which is part of the portal venous system. With portal HTN, increased pressure = esophageal varices = vomiting blood
What spinal tract carries pain and temperature fibers? Is this ipsilateral or contralateral?
Lateral spinothalamic tract, causes contralateral issues
Where does the posterior cerebral artery originate and what does it supply?
Originates from the basilar artery and supplies most of the occipital lobe. Infarctions lead to contralateral homonymouos hemaniopsia with macular sparing.
What is uniparental maternal heterodisomy? How is it different from uniparental isodisomy?
Uniparental heterodisomy = inheritance of a pair of nonidentical chromosomes from a single parents resulting from an error during meiosis I.
On chromosome 7 = itrauterine growth restriction, short stature, psychomotor development issues caused by genomic improting of growth genes; You can epigenetic modification of one copy where it is methylated.
Uniparental isodisomy = inheriting a pair of identical chromosomes caused by errors during Meiosis II.
What is intracranial pressure impacted by/ What is the most significant impact?
Brain volume, blood volume, and CSF, most significantly changes in PaCO2 which is changed based on tidal volume and respiratory rate. Increases in Co2 = increase in ICP
How does homocystinuria present? What enzyme has a defect?
Intellctual disability, Marfanoid habitus and long limbs, ocular lens subluxation, vascular disease, risk for intravascular thrombosis, and MI at a young age
Results from deficiency of multiple enzymes, including cystathionine b-synthase = increased homocysteine
What can be used to treat diabetic neuropathy? How does it work?
Substance P depletion because of capsaicin cream = agonist of TRPV1 on nociceptive nerves = depletes nerve fibers of substance P which limits nociception.
What prophylaxis to neonates get to prevent bacterial conjunctivitis? What bacteria is it caused by?
Get topical prophylaxis to prevent N gonorrhoeae and C.trachomatis; Erythromycin is used which binds to bacterial 50s ribosomal subunit and prevents bacterial protein synthesis
What substance causes erythema, warmth, and edema?
Bradykinin (also histamine and prostaglandin-E2) are inflammatory mediators that promote vasodilation and innate immune response
What is Leukocyte Adhesion Deficiency? WHat is the defect and what is impacted?
LAD = defect in the attachment of leukocytes to the vascular endothelium due to dysfunctional CD18 protein (integrins) = no normal attachment because leukocytes can’t adhere to the vascular endothelium
Presents with recurrent bacterial infections, impaired wound healing, and delayed detachment of umbilical cord after birth
What is the strongest risk factor for development of pancreatic cancer?
Cigarette smoking!
How does our body maintain adequate serum glucose during prolonged exercise? Where is it stored? What supplies glucose?
Liver and skeletal muscle = primary areas where glycogen is stored
Liver and kidney participate in gluconeogenesis and help release free glucose into the serum to maintain euglycemia
What is borderline personality characterized by? What about histrionic?
BPD = unstable sense of self, emotional dysregulation, and tumultuous relationships - suicidal gestures, desperately avoid abandomnent, and idealize or devalue other people
Histrionic = theatrical, superficial expressions of emotion that garner attention from others - dressing in seductive ways, not suicidal
How does folate deficiency manifest? What are risk factors?
Megaloblastic anemia from impaired erythrocyte DNA synthesis with risks including alcohol abuse, malnutrition, and high cell turnover like pregnancy/sickle cell. Acts as a cofactor for methylmalonyl-CoA to succinyl CoA –> increase in methylmalonic acid and homocysteiene
What is acute renal allograft rejection mediated by? Which MHC does it recognize?
Host CD8+ T lymphocytes recognize class I MHC molecules on allograft cells leading to transplant rejection within 6 months.
What does human herpesvirus 6 looks like? What does it cause?
Cause of roseola infantum - high fevers and blanching, macular eruption forms on neck and trunk and spreads outwards to face and extremities
What is the difference and main features distinguishing Ascaris Lumbricoides and Trichuris Trichiura?
A. Lumbricoides: endemic to India/Asia from foood and water - larval infiltration of intestinal wall, mature
Trichuris Trichuiuria: Intestinal worm, but only about 4 cm in length. Sx include nocturnal diarrhea, hematochezia, and dysentry, may also get rectal prolapse
Supplements that contain licorice have what impact on the body? How might it manifest
Licorice has active ingredient glycyrrhetinic acid/enoxolone, which inhibits 11-b hydroxysteroid dehydrogenase Type II –> catalyzes conversation of cortisol to cortisone in zona fasiculata so with inhibition, have increased cortisol to cortisone ratio = mineralcorticoid effects that inhibit RAAS and decrease serum concentrations of associated hormones
In the sympathetic trunk, what role does norepinephrine play?
Preganglionic sympathetic nerves release ACH onto postganglionic sympathetic nervers which release norepinephrine to stimulate smooth muscle of viscera and blood vessels
Difference between a case control and a cohort study?
Case-control looks at association between an exposure and an outcome. Identifies group with the OUTCOME (cases) and without the outcome (COnTROLS) and then compared their exposure.
In a cohort study, a group of patients is identified and followed to see whether an exposure is associated with an outcome of interest.
What are the features of Von Willbrand disease? What lab tests show this?
Symptoms: AD, epistaxis, gingival bleeding, petechiae, easy bruising, menorrhagia
Increased BT, decreased factor VIII activity, suppressed ristocetin cofactor activity
What part of the tubule does Hydrochlorthiazide and other thiazide diuretics exhibit its effect?
Inhibits sodium and chloride reabsorption in the distal convoluted tubule by inhibiting sodium-chloride transporter channel
What is the formula for steady-state concentration?
What is hypobetalipoproteinemia?
Defects in apolipoprotein B (APOB) = malabsorption of fats and steatorrhea, failure to thrive, hepatic steatosis and cirrhosis
APOB = role in chylomicrons, VLDL, and LDL-cholesterols.
What nerve innervates the deltoid and rotator cuff? What happens if it is compressed?
C5-C6 cervical node roots = innervate deltoid and rotator cuff, compression = weakness of upper extremity abduction
What are changes in maternal physioogy during pregnancy? Why do respirations increase?
Increased CO, increased oxygen demand, increased minute ventilation because of increased CO2 sensitivity due to fetal metabolic CO2 production –> increased CO2 is expired from lungs by mom
Congenital Adrenal Hyperplasia - how does it present and what enzyme is messed up?
CAH = adrenal enzyme deficiencies leading to issues with synthesis of cortisol. 21-hydroxylase is most common and presents in genetic FEMALES with virilization and hypoaldosteronism during infancy. Nonclasically can present in young adult with virilization only. Leads to buildup of 17-hydroxyprogesterone.
What is the formula for NNT?
NNT=1/ARR (absolute risk reduction)
What is the mechanism of propranolol?
Class II antiarrythmic = prolongs the slow, spontaneous depolarization = slower heart rate = decreased slope of diastolic depolarization
Compare and contract Churg-Strauss and Wegener Granulomatosis
Churg-Strauss = small vessel vasculitis with symptoms like asthma, ear, nasal and sinus inflammation, peripheral neuropathy, arthralgias, skin lesions with granulomatous nectortizing vasculitis and eosinophilia.
Wegener: nectoritzing small vessel vasculitis presenting with sinopulmonary disease and kidney disease –> episataxis, hemoptysis, hematuria
What are the differences in presentation with Chancroid, HPV, and Syphilus, and Genital herpes?
Chancroid: exudative painful ulver with inguinal lymphadenopathy with H. Ducreyi
Herpes: painful vessicles and erosions, shallow, lymphadenopathy
HPV: genital warts - soft and fleshy from HPV 16,18, 31, 33
Syphilis: multiple stages, painless chancre, secondary with fever/lymphadenopathy, tertiary with aortitis and gummas
What does aortic stenosis look like on a cardiac pressure tracing? What is it indicative of?
Large peak pressure difference between LV and aorta = early onset aortic stenosis from congenital bicuspid valve.
What is reciprocal inductive signaling, and what is an example?
Process by which two distinct cell populations impact differentiation of eachother through signaling. Example = uteric bud and mesenchyme –> generate the mature kidney
What is the Hardy-Weinberg Equilibrium formula?
Frequency of a dominant and recessive allele in a population
p+q = 1
P^2 +2pq +q^2= 1
What does hemolytic uremic syndrome manifest as?
Acute renal failure, thrombocytopenia, microangiopathic hemolytic anemia (MAHA), seen in children with E.coli
How do you calculate incidence?
of new cases of a disease / population at risk (remove initial diagnosed to see the group at risk)
What is MPO deficiency?
Immunodeficiency from inability to produce hydroxy-halid free radicals in phagolysosomes, usually get recurrent candida infections
What is necrotizing enterocolitis? How does it present? What age?
Associated with premature infancy and has inflammation and necrosis of the bowel wall leading to abdominal distention, tenderness, vom, blood diarrhea, lethargy, and feeding intolerance.
When mast cells degranulate in a type 1 hypersensitivity reaction, what do they release?
First histamine, then prostaglandins, leukotrienes, and inflammatory mediators
How does HIV mutate?
HIV reverse transcriptase = error prone = viral resistance
What diseases are only inherited from the mom? What is the term for this?
Mitochondria diseases only inherited through mom. Hetroplasmay = presence of normal and mutated mitochondrial DNA = variable expression of diseases
What lab values (Potassium, chloride, bicarbonate) are impacted in bulemia w/ abuse of laxatives?
Low bicarb, low potassium, increased chloride
