USMLE World 1 Flashcards
relantionship between prevalence and PPV
Prevalence ∝ PPV/NPV
top cancers by incidence
- breast/prostate; 2. lung; 3. colon
top cancers by prevalence
- breast/prostate; 2. colon; 3. lung
respiratory epithelium
cilia is present all throughout; serous, mucous glands, goblet cells and cartilage dissappear
koilocytes
pyknotic superficial immature squamous cell with dense irregularly stainning cytoplasm and perinuclear clearing
osteocytes
gap junctions
elastase
protease secreted by alveolar macrophages
dynein
ATPase associated with microtubule doublets; retrograde transport and ciliary flagellar movement
type II pneumocytes
production of surfactant and regeneration of type I pneumocytes after injury
Brunner glands
only in duodenum
Peyer patches
mostly in ileum
histology of large intestine
goblet cells but no pits or villi
stratified epithelium of the respiratory tract
oropharynx, laryngopharynx, anterior epiglotis, true vocal cords
strep bovis endocarditis
associated with colon cancer 25% of cases
dextran adherence
viridans strep adheres to deposits of fibrin in damaged valves
congenital rubella
sensorineural deafness, cataracts and PDA
fulminant hepatitis
HEV. Not associated with chronic hepatitis.
HCV immuno resistance
antigen variability is responsible for lack of immune response; lacks 3’-5’ proof reading activity
non sorbitol fermenter in McKonkey’s
EHEC:0157
dyptheria vaccine (DPT)
antigen is beta subunit of diptheria endotoxin; active immunity IgGs
staph epidirmidis Rx
vancomycin
cryptococcus infection pathogenesis
asymptomatic infection of lungs –> meningitis; associated with pigeon droppings
toxoplasmosis MRI
ring-enhancing lessions
Hib vaccine
cell wall polysacchride conjugated with diptheria or tetanus toxoid
congenital toxoplasmosis
hydrocephalus, intracranial calcifications, chorioretinitis due to in-utero infection
n. meningitidis route of entry
nasopharynx –> blood –> choroid plexus
H. influenzae route of infection
pharynx –> lymphatics –> meninges
pneumococcus route of infection
middle ear –> meninges
viral UTI
adenovirus causes hemorrhagic cystitis
subcutaneous mycosis
sporothrix in gardners
interstitial pneumonia
CMV in AIDS patients; nuclear inclusion bodies; also atypical bugs: mycoplasma, RSV, chlamydia
legionella associations
water aerosols and humidifiers
catalase+ bugs
staph, pseudomonas, serratia, aspergillus, nocardia
cold aglutinins
IgM antibody formed against mycoplasma and EBV; reaction with RBCs results in anemia
types of aspergyllosis
invasive (neutropenic patients); colonizing (fungus ball); allergic (asthmatic patients)
epiglotitis
H. influenzae; sore throat, fever, drooling, airway obstruction, stridor
virulence factors of mycobacteria
sulfatides, tuberculin and serpentine cords
Legionaire’s disease
high fever, pneumonia and diarrhea in a chronic smoker
clue cells
squamous epithelial cells covered by Gardnerella seen on wet mount
POMC
proopiomelanocorticotropin cleaved to yield ACTH, MSH and beta endorphin
opiod receptors
increase gK –> decrease pain
scotoma
visual field deficit surrounded by zones of normal vision indicates damage to macula in retina; retinitis pigmentosa, multiple sclerosis, diabetic nephropathy
reperfusion arrhythmia
caused by tPA, reteplase, tecteplase fibrinolytic therapy
osteoblast markers
LAP
osteoclast markers
acid phosphatase, urinary hydroxyproline
space constant
measure of the ability of an impulse to travel down an axon; low SC –> decrease impulse (ME)
bounding femoral pulse
water-hammer pulse in aortic insufficiency
pulsus parvus et tardus
aortic stenosis
blood transfusions
contain citrate which chelates calcium and results in hypocalcemic paresthesia
iron regulation
by epithelial cells of the gut and intracellular ferritin
law of conservation of masses
total flow = flow velocity * cross sectional area; flow in = flow out
AV shunt volume loop diagram
increased preload
conduction velocities of heart tissue
AV node (0.05m/sec); ventricular muscle (0,3m/sec); atrial muscle (1.1m/sec); purkinje (2.2m/sec)
source of ACE
lungs
RV/TLC in obstructive diasese
increased RV more than TLC
hypoxic vasoconstriction
as oxygen content decreases, arteriolar resistance increases
perfusion-limited
when substances equilibrate across the membrane
diffusion-limited
when substances do not equilibrate across membrane
diffusion of oxygen
perfusion limited
oxygen supplementation in COPD patients
COPD patients have chronic hypoxia and hypercapnia; hypoxia is main ventilatory drive so use O2 supplementation carefully
brown adipose
termogenin produces heat
pulmonary vascular resistance
increases as air is inhaled and on forced expiration due to increase tension of lung parenchyma
pathophysiology of pneumoconiosis
fine dust particles are phagocytosed but alveolar macrophages release growth factors that stimulate fibroblast proliferation and fibrosis
lung clearance mechanisms
large particles are trapped in upper respiratory tract; medium particles are cleared by mucocilliary transport; fine particles < 2.5um are phagocytosed
causes of decreased lung compliance
pulmonary edema, pulmonary fibrosis, decreased surfactant, pneumoconiosses, kyphoscoliosis
alveolar gas equation
PAO2 = 150 - (PaCO2/0.8); PaO2 is given value; use PAO2 to calculate A-a gradient: PAO2 - PaO2
hypoxemia in pulmonary embolism
due to Va/Q mismatch
Va/Q mismatch
increased A-a gradient
hypoventilation
hypoxemia with normal A-a gradient
causes of hypoxemia
hypoventilation, Va/Q mismatch, diffusion impairmnet, right-left shunt
lipid absorption and digestion
absorption –> jejunum; digestion –> duodenum
S4 heart sound
presystolic before S1; indicates decreased compliance of left ventricle
ASD murmur
wide fixed S2 splitting with increased pulmonic valve pressure
prevention of calcium stones
increase water intake and increase citrate which chelates calcium
pericardial tamponade
muffled distant heart sounds, hypotension, increased central venous pressure and jugular regurgitation; post MI complication results in decreased venous return and hypotension
cardiac hybernation
hypokalemia of heart muscle due to chronic ischemia in CAD; reversible with bypass revascularization
ischemic preconditioning
resistance to infarction by myocytes exposed to chronic ischemia
ventricular remodeling
adaptation in mass, volume and shape to compensate for increased hemodynamic load
chemical mediators of atheromas
PDGF and TxA2 by platelets
reperfusion injury
secondary to oxygen free radicals, mitochondrial damage and inflammation
billiary tract enzymes
gammaglutamyl transferase and alkaline phosphatase
liver function tests
PT, albumin, cholesterol
hepatic integrity enzymes
AST, ALT
alkaline phosphatase differentiation
if increased alkaline phosphatase, check gammaglutamyl transferase to differentiate LAP from liver AP
aromatase
converts androgens to estrogens; stimulated by FSH in granulosa cells; might be deficient in female pseudohermaphrodite or elevated in male pseudohermaphrodite; inhibited by anastrozole
cardiac contractility
depends on aerobic glycolysis to produce ATP and creatine phosphate; ischemia leads to loss of contractility in 30 seconds
paradoxycal thromboembolism
thrombus passes from veins to arteries through an ASD; ASD produces fixed splitting of S2
natriuretic peptide
synthesized by atria upon stretch and right ventricle (Brain natriuretic peptide BNP)
cyanosis improves with squatting
tetralogy of fallot; increased TPR/PVR ratio increases pulmonary flow
absence of edema in early CHF or cor pulmonale
because intrathroracic pressure becomes more negative (COPD, etc), venous return and lymphatic drainage increase
holosystolic murmur
mitral insufficiency, tricuspid insufficiency, VSD
S3 heart sound
left ventricle volume overload in CHF or mitral insuficiency
TGF beta
tumor suppressor, angiogenesis, fibroblasts
metalloproteinases
collagen degradation; released by macrophages; may result in rupture of atheroma and AMI
hemodynamic changes in aortic stenosis/left ventricular hypertrophy
acute atrial fibrillation –> hypotension –> pulmonary edema due to decreased preload and CO
cholestasis
leads to osteomalacia due to ADEK malabsorption
Wolf-Parkinson
pre-excitation due to accesory bundle of Kent; delta wave on ECG, decreased PR interval and widened QRS, treat with class Ia and III antiarrhythmics
isolated systolic hypertension
age related stiffening of the aorta
aortic stenosis
increased left ventricle to aorta pressure gradient
aortic insuficiency
palpitations due to increased stroke volume; head pounding due to high amplitude pulsations; “head bobbing” due to widened pulse pressure
mitral stenosis murmur
opening snap in early diastole after aortic component of S2 (immediately after closure of aortic valve) plus diastolic murmur
acute mitral insufficiency
due to rupture of cordae tendinae or prosthetic valve failure don’t have time for atrial adaptation; decreased compliance leads to pulmonary edema
mitral stenosis severity
S2-to-opening snap is short –> more severe
hepatic encephalopathy
decreased clearance of gut amonia by damaged liver –> increased GABA receptor activity
gynecomastia in cirrhosis
decreased estrogen metabolism by liver –> gynecomastia, palmar erythema, testicular atrophy, decreased body hair
sweat in cystic fibrosis Vs. normal people
normal –> hypotonic; CF –> hypertonic
uric acid stones
precipitate in acid collecting ducts; Rx alkalinization of urine + hydration + indomethacin/colchicine
squamous lung cancer paraneoplastic syndrome
PTH-like peptide
RANK receptors
mediate osteoclast differentiation; low estrogen upregulates RANK –> increased bone resorption –> less bone mass
why is H. pylory in duodenum
only colonizes gastric tissue; if present in duodenum it’s due to metaplasia
cystic fibrosis secretions osmolarity
all isotonic except sweat which is hypertonic
infectious esophagitis
CMV (linear ulcerations), candida (pseudomembranes), HSV-1 vesicles/ulcers
pancreatic necrosis
intracellular activation of trypsin and all other proteolytic enzymes
osteoporosis risk factors
smoking, menopause, corticosteroid therapy, physical inactivity, caucassian, low BMI, alcohol
IL-5
associated with asthma; isotype switch to IgA
water deprivation test
increased urine osmolarity if primary polydipsia; no change in diabetes insipidus
triglycerides in insulin resistance
triglycerides and FFA increase insulin resistance in overweight individuals
somatostinoma
inhibits all GI hormones –> billiary stones due to decreased CCK and hyperglycemia due to decreased insulin
how does hyperprolactinemia result in osteoporosis
hyperprolactinemia –> hypogonadism –> decreased estrogen –> osteoporosis
bone changes in hyperparathyroidism
subperiosteal thinning
dexamethasone test
low dose suppress cortisol –> Cushing syndrome; high dose suppresses cortisol –> pituitary Cushing; no suppression –> ectopic ACTH
sex hormones in bone growth
sex hormones promote bone growth and epipheseal closure –> short stature in spite of growth spurt
hormonal changes with glucocorticoid therapy
decreased CRH, ACTH and cortisol
hormonal changes in cryptorchidia
affects seminiferous tubules and Sertoli cells –> decreased inhibin and increased FSH
hormonal changes in steroid therapy
increased testosterone, decreased LH and low sperm count
Lisch nodules
neurofibromatosis
Kayser-Fleischer rings
Wilson’s
chromosome 8
c-myc
mitochondrial diseases
myoclonic epilepsy, Leber, MELAS
Friederich ataxia
progressive ataxia due to degeneration of spinocerebellar and dorsal column tracts, hypertrophic cardiomyopathy (50%), skeletal abnormalities, diabetes (10%), autosomal recessive
Lesch Nyhan
x-linked recessive deficiency of hypoxanthine guanine phosphorybosyl transferase (HGPRT)
heteroplasmy
mitochondrial inheritance shows phenotype depending on how many mitochondria patient has
Prader-Willi deletion
paternal 15q deletion but affected gene is from mother
genetic imprinting synonym
unisomal dysomy
HNPCRC mutation
DNA mismatch repair enzyme
Xeroderma mutation
DNA excision repair enzyme
methylation
silences genes
acetylation
activates genes; acetylation is on lysine residues
alpha-feto protein
increased in neural tube defects; decreased in Down’s
Sturge-Weber
port-wine stains and angiomas on the face and ipsilateral arteriovenous malformation in the meninges
Osler-Weber-Rendu
hemorrhagic telangiectasia, recurrent epistaxis and GI bleeds
Tuberous sclerosis
autosomal dominant; mental retardation and seizures, angiofibromas, angiomyolipoma in the kidneys (80%); rhabdomyoma in the heart
probability that a person is a carrier if both parents are carriers
2 of 3
CFTR abnormality
impaired posttranslational processing with subsequent degradation
t(15,17)
translocation of retinoic acid receptors, no differentiation of myeloblasts
45XO karyotype
due to mitotic errors after fertilization
cystic hygroma Vs. brachial cyst
brachial cysts are uniloculated; hygroma has lymph tissue and are much larger (associated with Turner)
Kallman’s syndrome
delayed puberty and anosmia, absence of GnRH; problem is in the hypothalamus
G6PDH deficiency hereditary pattern
x-linked recessive
22q deletion
DiGeorge
antinflammatory cytokines
IL-10 and TGF-beta
diabetic nephropathy drug of choice
ACE inhibitors and AT-1 blockers
blood findings in ACEi therapy
decreased angiotensin II –> decreased GFR –> increased serum creatinine
drugs that cause tubular necrosis
aminoglycosides, contrast agents, cisplatin, ampB, foscarnet
gold therapy
membranous nephropathy
determinants of volume of distribution
low volume of distribution: highly charged, bound to proteins, large molecular weight; large volume of distribution: drug is small and lipophylic
pathophysiology of angina
heart uses most energy from beta oxidation which consumes more oxygen per ATP produced than aerobic glycolisis; fatty acid synthesis inhibitors shift energy usage from b-oxidation to aerobic
edrophonium test
if symptoms improve –> myasthenia or myasthenia crisis (increase dose); if symptoms don’t improve –> cholinergic crisis (stop dose)
lithium toxicity
can be caused by NSAIDs and thiazides because they increase sodium and lithium reabsorption
on-off phenomenon
levodopa therapy; its unpredictable
low MAC
high potency
high solubility in blood
slow onset of action
Rx bronchiolitis
ribavirin
isoniazid side effects
vitamin B6 deficiency (sideroblastic anemia); ataxia, paresthesia, decreased pain sensation (peripheral neuropathy); hepatitis
glucocorticoid inhalant side effects
oral candidiasis (treat by washing mouth)
N-acetylcysteine
mucolytic used in CF; cleaves mucuous disulfide bonds
prophylaxis of meningitis
rifampin
bosentan
used for pulmonary hypertension; antagonist of endothelin receptors
Leber’s optic neuropathy
mitochondrial inheritance; optic nerve degeneration; mutation arginine to histidine in ND4 gene affects subunit 4 of NADH dehydrogenase complex
myoclonic epilepsy with ragged fibers
mitochondrial inheritance; myoclonus, seizures, ataxia, mitochondrial myopathy; ragged look of mitochondria in muscle
