NPLEX I flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Rate-limiting enzyme of glycolysis

Phosphofructokinase-1 catalyzes the committed step of glycolysis and is inhibited by ATP and citrate while activated by AMP and fructose-2,6-bisphosphate.

Chemiosmotic ATP yield

Each NADH oxidized in the electron transport chain yields roughly 2.5 ATP, and each FADH2 yields roughly 1.5 ATP via ATP synthase.

Km and enzyme affinity

Km is the substrate concentration giving half-maximal velocity. A low Km indicates high affinity; competitive inhibitors raise apparent Km without altering Vmax.

Hardy-Weinberg carrier frequency

For an autosomal recessive condition in equilibrium, carrier frequency equals 2pq, where p and q are the allele frequencies and q-squared is the disease incidence.

Resting membrane potential basis

Resting potential near -70 mV in neurons depends chiefly on potassium permeability, maintained by the Na+/K+ ATPase moving three sodium out per two potassium in.

Starling force equation

Net capillary filtration equals capillary hydrostatic plus interstitial oncotic pressure minus interstitial hydrostatic plus capillary oncotic pressure; hypoalbuminemia promotes edema.

Innate versus adaptive immunity

Innate immunity acts within minutes through neutrophils, macrophages, complement, and NK cells; adaptive immunity uses clonal lymphocyte selection and generates immunologic memory.

Respiratory versus metabolic compensation

Metabolic acid-base disorders are compensated by rapid ventilatory change, whereas respiratory disorders require renal compensation that develops over days.

Cardiac troponin kinetics

Troponin rises about three to six hours after myocardial injury, peaks near twenty-four hours, and may remain elevated for one to two weeks.

Diabetes diagnostic thresholds

Diabetes is diagnosed by fasting glucose at or above 126 mg/dL, two-hour OGTT at or above 200 mg/dL, or HbA1c at or above 6.5 percent.

Primary hypothyroidism laboratory pattern

Primary hypothyroidism shows an elevated TSH with a low free T4, whereas primary hyperthyroidism shows a suppressed TSH with elevated free T4 and T3.

Anemia by mean corpuscular volume

Microcytic anemia suggests iron deficiency, thalassemia, or chronic disease; normocytic suggests blood loss, renal disease, or hemolysis; macrocytic suggests B12 or folate deficiency.

Fractional excretion of sodium

A fractional excretion of sodium below one percent favors a prerenal cause of acute kidney injury, reflecting appropriate sodium retention by the kidney.

Distributive shock features

Distributive shock from sepsis, anaphylaxis, or neurogenic causes shows low systemic vascular resistance with warm extremities and bounding pulses in early stages.

Most common typical pneumonia pathogen

Streptococcus pneumoniae is the most frequent typical cause of community-acquired pneumonia; atypical causes include Mycoplasma, Chlamydophila, and Legionella species.

Hypertension first-line drug classes

First-line antihypertensives include thiazide diuretics, ACE inhibitors or ARBs, and calcium channel blockers; ACE inhibitors are avoided in pregnancy and bilateral renal artery stenosis.

Sensitivity and specificity formulas

Sensitivity equals true positives divided by true positives plus false negatives. Specificity equals true negatives divided by true negatives plus false positives.

Predictive value and prevalence

Positive predictive value increases as disease prevalence rises, while negative predictive value decreases as prevalence rises, even when sensitivity and specificity are unchanged.

Number needed to treat

Number needed to treat is the reciprocal of the absolute risk reduction; number needed to harm is the reciprocal of the absolute risk increase.

Relative risk versus odds ratio

Relative risk derives from cohort studies; the odds ratio approximates relative risk only when the outcome is rare, generally under ten percent.

Confidence interval interpretation

A 95 percent confidence interval excluding 1.0 for a ratio measure, or excluding 0 for a difference, indicates statistical significance at alpha equal to 0.05.

Clinical trial phases

Phase I assesses safety and dosing, Phase II assesses efficacy, Phase III compares against standard treatment, and Phase IV is post-marketing surveillance.

Screening test requirements

Screening tests require high sensitivity and a detectable preclinical phase with effective treatment; any positive screen is followed by a confirmatory test.

Drug half-life and steady state

Steady-state plasma concentration is reached after approximately four to five half-lives of consistent dosing; bioavailability is the fraction of dose reaching systemic circulation.

Henderson-Hasselbalch relationship

Plasma pH equals 6.1 plus the log of bicarbonate divided by 0.03 times carbon dioxide tension, linking respiratory and metabolic acid-base components.

Cellular energy from fatty acids

Beta-oxidation cleaves two-carbon units to acetyl-CoA for the citric acid cycle; ketone bodies form when hepatic acetyl-CoA exceeds cycle capacity.

Acute coronary syndrome management

ST-elevation myocardial infarction requires emergent reperfusion, either primary percutaneous coronary intervention or fibrinolysis when intervention is unavailable within recommended time limits.

Diabetic ketoacidosis findings

Diabetic ketoacidosis presents with hyperglycemia, anion-gap metabolic acidosis, and ketonemia; treatment uses isotonic fluids, insulin infusion, and potassium replacement.

Cirrhosis complications

Cirrhosis causes portal hypertension with ascites, esophageal varices, and hepatic encephalopathy; ascites is managed with sodium restriction, spironolactone, and furosemide.

Cohort study design

A cohort study follows exposed and unexposed groups forward in time to measure incidence and calculate relative risk and attributable risk.

Case-control study design

A case-control study identifies affected and unaffected individuals and looks backward at prior exposures, efficiently estimating odds ratios for rare diseases.

Lead-time bias in screening

Lead-time bias occurs when earlier detection appears to prolong survival by advancing diagnosis without changing the actual time of death.