USMLE Step 1 Items
Terms
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- action of finasteride?
- inhibits 5 alpha reductase; enzyme that converts testosterone -> dihydrotestosterone
- when pushing a piano across the floor, what transfers force from radius to ulna?
- interosseous membrane
- what structure allows enteric gram negative bacteria to be more resistant to penicillin G than gram positive bacteria?
- outer membrane
- in a woman, what will happen when 17-beta-estradiol peaks in the absence of progesterone?
- the estrogen peak will cause an LH surge and lead to ovulation
- what type of receptors are commonly used by peptide hormones that regulate growth, differentiation and development?
- tyrosine kinase receptors
- what brain structure is damaged in intention tremor, or tremor when attempting purposeful movement?
- cerebellum (ipsilateral side)
- in an elderly person, what muscle should be strengthened to try and avoid urinary incontinence?
- urogenital diaphragm
- what is the mean pO2 of fetal oxygenated blood?
- ~ 30 mmHg
- what is parathion?
- an organophosphate ACholinesterase inhibitor
- what is a urachal cyst?
- a cyst formed in the connection between the umbilicus and the apex of the bladder
- what is cycloplegia?
- paralysis of the ciliary muscle, so that the lens can't change focus for different distances
- name a drug that would cause mydriasis without producing cycloplegia. what is the mxn?
- phenylephrine, an alpha1 agonist
- anti-microsomal antibodies in the thyroid. disease?
- Hashimoto's thyroiditis
- what happens to reaction velocities when the enzyme concentration is halved?
- the velocities are halved along the curve
- what virus can cause severe pulmonary and hepatic dysfunction in an immune-compromised individual?
- CMV
- duodenal atresia of the fetus leads to polyhydramnios or oligohydroamnios?
- polyhydramnios - can't swallow amniotic fluid
- where are the characteristic hemorrhagic lesions in Korsakoff's syndrome?
- lesions: mammillary bodies, dorsomedial nucleus of thalamus, periventricular regions from 3rd to 4th ventricle
- damage to what part of the brain leads to problems with primary (immediate) memory?
- mammillary glands
- kids are vulnerable to what kidney disease following a viral upper respiratory infection?
- minimal change disease
- what 2 organs are derived from the 3rd pharyngeal pouch?
-
thymus: ventral part
inferior parathyroids: dorsal part - what are the calorie contents of carbs, proteins and fats?
-
carbs and proteins: 4 kcal/gram
fats: 9 kcal/gram - what enzyme deficiency is the most likely cause of hereditary hyperammonemia?
- carbamoyl phophate synthetase I
- the subscapular artery forms an anastomosis with branches of what other artery?
- subclavian
- what is damaged in ARDS? what are the sequelae?
-
diffuse injury to alveolar capillaries
leakage of fluid and proteins into the interstitium or alveoli to produce severe pulmonary edema -> thick hyaline membranes are formed from edema fluid and cellular debris - what bugs can be identified with clumping of latex beads coated with antibody and fibrinogen?
- gram-positive cocci
- what protein on staphylococci binds IgG?
- protein A
- what secretes mullerian inhibitory substance in males to cause regression of mullerian ducts?
- Sertoli cells
- what do you call the acute, reversible disorder affecting orientation, perception, cognition and reality testing?
- delirium
- name a group of muscles involved in vocalization that could be paralyzed with damage to the vagus nerve.
- cricoarytenoid
- artificial sweetener aspartame is a dipeptide of what 2 aa's?
- phenylalanine and aspartate
- the median nerve lies between what 2 structures in the wrist?
- flexor carpi radialis and flexor digitorum superficiale
- what enzyme is deficient when the liver stores too much glycogen with normal structure?
- glucose-6-phosphatase
- what does glucose-6-phosphatase do in the liver?
- removes phosphate group from glucose
- why are loading doses of medications administered?
- because a drug can bind heavily to plasma proteins, making less available
- how does cocaine act on neurons?
- blocks monoamine reuptake (NE, dopamine, serotonin)
- what 2 muscles control pupil diameter and how are they innervated?
-
radial dilator muscle: contracts (mydriasis) with alpha-receptor stimulation
pupillary sphincter muscle: constricts (myosis) with muscarinic (ACh) stimulation - how does the drug tyramine work?
- indirect-acting sympathomimetic: taken up by sympathetic nerve terminals and pushes NE into synapse
- what type of fluids are needed to increase BP in a volume-depleted patient?
- remains in ECF compartment and have tonicity similar to plasma
- how many liters of fluid must be added to the ECF to replace 1 liter of plasma fluid?
- 3 liters (2 go to interstitial space, 1 to plasma)
- granulomatous colitis is another term for what disorder?
- Crohn's disease
- an elderly person with history of diverticulosis has increased risk for what complication?
- GI hemorrhage
- an elderly patient presents with symptoms resembling "appendicitis on the left", tenderness to palpation, fever and leukocytosis. diagnosis?
- diverticulitis
- a young girl hasn't eaten for 2 days. what source of fuel are her muscles now using?
- serum fatty acids
- how do amphetamines work?
- enter nerve terminals and displace NE
- in what layers do you find the blood vessels that supply the skin?
- deep and superficial layers of the dermis
- which blood vessels in the skin are oriented horizontally?
- those of the deep dermis