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Usmle > Block 16 > Flashcards

Block 16 Flashcards

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USMLE® Step 1 flashcards
1
Q

RNA polymerase types and location
DNA polymerase function and location
DNA endonuclease function and location

A

RNA polymerase I = found exclusively in the nucleolus , form essential ribosomal component (18S, 5.8 S, 28 S)
RNA polymerase II= found around the nucleus and nucleolus, responsible for making mRNA, snRNA, and micro RNA
RNA polymerase III= transcribes DNA to form snRNA such as tRNA and 5S rRNA.
DNA polymerase= responsible for replication and repair found throughout the nucleus.
DNA endonuclease= found in nucleoplasm and breaks phosphodiaster bonds within nucleotide chain, responsible for repair and RNA splicing

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2
Q

Mullerian aplasia

A

(Also called mayer rokitansky kuster hause syndrome)
Normally mullerian duct give rise to fallopian tubes, uterus cervix, and upper vagina by 20 weeks of gestation.
- defective development or congenital absence of organ or tissue —> variable uterine development, short vagina.
- amenorrhea with normal secondary sexual characterestics
- patients have normal ovaries which secretes estrogen —> secondary sexual characteristics.

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3
Q

Patients with mullerian aplasia (MRKH) , may have extra genital complication —> ?

A

Urological malformations such as Unilateral renal agenesis , ultrasound should be done

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4
Q

Efficacy vs potency

A

Efficacy = intrinsic ability of a drug to elicit and effect such as receptor activation or dilation of a vessel. Its a measure of the maximum ceiling of activity (E-max) of a drug with respect to particular pharmacodynamic end point.
Potency = refers to the dose of the drug that is required to produce a given effect. Its primarily affected by the affinity of the drug for its receptor and the amount of drug that is able to reach the target tissues, therefore a drug that binds to their receptors with a higher affinity have a greater potency.
The lower the ED50 , the more potent the drug is.

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5
Q

Fenoldopam

A

Dopamine- 1 receptor agonist,. Stimulates and activates cAMP —> vasodilation in most arterial beds —> decrease in Systemic BP.
- Renal vasodilation is particularly prominent and leads to increased renal perfusion, naturesis and diuresis.

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6
Q

Hypertensive emergency vs urgency

A 
Urgency= severe hypertension with no evidence of end organ damage.
Emergency= severe hypertension with end organ damage 
Such as (ACS, encephalopathy, pulmonary edema, AKI, aortic dissection, papilledema, aortic dissection) 
Treated with dopamine agonist (e.g fenledopam)
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7
Q

Changes after MI by time frame

A

0-4 hrs : minimal changes
4-12 hrs: early coagulation necrosis, edema , hemorrhage and wavy fibers.
12-24 hrs: coagulation necrosis and marginal contraction band necrosis
1-5 days: neutrophilic infiltrates
5-10 days : macrophage phagocytosis of dead cells
10-14 days: granulation tissues and neovascularization
2 weeks to 2 months: scar formationm

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8
Q

IL- 4 and IL-5 stimulate which Ig

A

IL-4 —> IgE (also IL-13)

IL-5 —> IgA

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9
Q

If a patient with angina cant tolerate aspirin he should receive

A

Clopidogrel

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10
Q

PAD drugs

A

Peripheral artery disease
Pentoxyfilline
Cilostazol

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11
Q

Phenylketonuria deficiency in which enzymes

A
  1. Most cases are due to phenylanine hydroxyalse deficiency —> deficient phenylanine.
  2. Less commonly deficiency in BH4 (tetrahydrobiopetric) due to deficiency in dihydropteridine reductase deficiency. This will lead to decrease serotonin (tryptophan cant be converted to 5-hydroxytryptophan which then converted to serotonin )
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12
Q

Peptidoglycan cell wall in Gram positive bacteria

A

Provides the shape of the bacterium as well as resistance to osmotic pressure.
-if treated with antibiotic that acts on it (e.g cephalosporins pencillins, and vancomycin) —> can disentegrate bacteria because it wont be resistant to osmotic pressure

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13
Q

Supplementation for breastfeed infants

A
  1. Vitamin D (especially with lack of sun exposure or african american)
  2. Iron (preterm/ low birthweight.
  3. Vitamin K (at delivery)
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14
Q

Bupropion side effect

A
  • its an antidepressant that similar in structure of amphetamines —> inhibits reuptake of dopamine and NE. Commonly used to treat major depression.
  • seziures are potential side effect of bupropion therapy, especially in high doses.
  • contraindicated in sezuires history or bulemia/ anorexia history.
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15
Q

Vanlefexine AE

A

Hypertension

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16
Q

Fastest to slowest cardiac tissue conduction

A
  1. Prukinje —> atrial muscle —> ventricular muscle —> AV node
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17
Q

B12 deficiency in spinal cord lesion

A
  1. Subacute combined degeneration of dorsal coulmns( position and vibration sense, positive romberg ataxia)
  2. Lateral corticospinal (spastic paresis)
  3. Spinocerbellar tracts (ataxia)
  4. Pts may develop atrophic glossitis (smooth,shiny erythmatous tongue)
18
Q

TPR equation

A 
1/Rt= 1/TPR 
1/Rt= 1/R1 + 1/R2 + 1/R3  +1/R4.... 
if for example  all  1/R1 + 1/R2 + 1/R3  +1/R4 were equal to 2
So 
1/TPR
TPR= 1/2 +1/2 +1/2 + 1/2 = 2 mm 
1/TPR = 0.5
19
Q

Superior messenteric artery syndrome

A
  • intermittent intestinal obstrucion symptoms (postprandial pain and billous vomiting)
  • when transverse (third portion) part of dudenum gets compressed between SMA and aorta.
  • occurs with low body weight and malnutrition usually.
20
Q

Lamotrigine can cause (AE)

A
  1. SJS or toxic epidermal necrolysis
21
Q

Acute adrenal crisis
Etiology
Clinical
Treatment

A

Etiology: adrenal hemorrhage or infarction, acute illness/ injury/surgery in patients with chronic adrenal insuffeciency or long term corticoids use
Clinical feature:
1. Hypotension and shock
2. Nausea/vomiting/abdominal pain and hypoglycemia
3. Weakness
4. Fever
5. Hypopegmentation
Treatment:
Hydrocortisone or dexamethasone with high IV fluids

22
Q

Hepatodudenal ligament includes

A 
Common bile duct
Hepatic artery
Hepatic portal vein 
(Portal triad)
Occlusion of it can be done surgically to identify vascular source. If liver bleeding doesnt cease, its likely it hasnt been the cause of bleeding rather the IVC or hepatic veins.(pringle maneuver)
23
Q

West nile virus - features, clinical and diagnosis.

A
  • positive sense, ssRNA flavivirus transmitted by culex mosquitos most commonly in summer.
  • Rash , neurological manifestaion (encephalitis associated with flaccid paralysis syndrome), meningitis
  • diagnosis can be done with positive CSF anti-WNV antibodies.
  • management -> supportive
24
Q

Acid base disorders appropriate compensation

A
  1. metabolic acidosis = PaCO2= 1.5 (serum HCO3-) +8 +- 2
  2. metabolic alkalosis = increase in paCO2 by 0.7 mm Hg for every 1 mEq/L rise in HCO3-
  3. Acute respiratory acidosis= increase serum HCO3- by 1 mEq/L for every 10 mm Hg rise in PaCO2
  4. Acute respiratory alkalosis= decreased serum HCO3- by 2 mEq/L for each 10 mm Hg decrease in PaCO2.
25
Q

Jaw claudication in old patients indicates

A

giant cell arteritis
Along with polymalgia rheumatic, headache, visual disturbances, weight loss and fever.
Treated with corticosteroids
Treat also with tocilizumab

26
Q

Trabecular thining of the bone with fewer interconnections is charactrized of

A

Osteoporosis, also persistence of primary spongiosa in the medullary cavity with no mature trabeculae is a classic finding.(marble bone disease)

27
Q

Subperiosteal resorption of bone with cystic degeneration seen in

A
  • primary hyperparathyrodism.
  • symptoms include:
    Stone, bones, abdominal groans (peptic ulcer), psychic moans(psychiatric disorders).
    -granular salt and pepper skull and osteolytic cyst in long bones can be seen.
28
Q

DNA binding domain receptor for which substances

A
29
Q

Collagen subtypes

A

Collagen type I = dermis, bone ,tendons, ligaments ,cornea, blood vessels and scar tissues
Collagen type II= nucleus pulposus, cartilage, viterous humor
Collagen type III= granulation tissue, skin, lung, intestine, blood vessels, bone marrow, lymphatics.
Collagen Iv= basement membrane

30
Q

1 gram protein equals (callories)

A

1G protein and carbohydrate = 4 callories

1 G of fat = 9 callories

31
Q

On-off phenomenon

A

Its present in the long treatment of parkinsons with levodopa which can be unpredictable.

  • as PD progress the theraputic window for levodopa narrows( either due to natural or levodopa induced nigrostriatal degeneration) .
  • in advanced cases motor flactuations can occur independently of medication and may become unpredictable
32
Q

HHV-6 on infants

A

Roseola infantum
Age <2years
Clincial features - 3-5 days of high fever( may precipitate a seziure) followed by blanching maculopapular rash

33
Q

Acute gout treatment

A
  1. NSAIDS (anti-inflammatory drugs preferred)

2. colchicine

34
Q

Facial nerve innervation function

A
  1. Motor input to facial muscles
  2. Parasympathetic innervation to lacrimal, submandibular and sublingual salivary glands
  3. Special afferent fibers for taste from anterior 2/3 of the tongue
  4. Somatic afferents from the pinna and external auditory canal.
35
Q

Face sensation is given through

A

Trigiminal nerve

36
Q

Chrons disease on light microscopy

A

-non-caseating granulomas and transmural inflammatory infiltrates.

37
Q

Hematogenous osteomyelitis

A

Disease that predominantly affects children, particulary boys.

  • usually affects the METAPHYSIS of long bones, as this region conatins slow flowing, sinusoidal vasculature that is conductive to microbial passage.
  • it begins with a seeding event that causes acute cellulitis of bone marrow —> inflammation within confined boney space —> increased intramedullary pressure, which comprimises blood flow and forces infection exudate through vascular channels into the cortex and periosteal regions. —> ischemia —> necrosis.
38
Q 
Protein M function in Gram positive 
Teichoic acid function 
Streptokinase
Hylaronate 
Streptolysin
A

Protein M—> inhibit phagocytosis
Teichoic acid —> minor LPS like endotoxin effect
Streptokinase—> catalyzed plaminogen to plamin results in fibrin digestion and faciltating spread in infected site
Hylaronate—> present in capsule and has antiphagocytic activity
Streptolysin —> lyses RBC

39
Q

Saccular aneurysm on CT

A

Hyperdense areas seen within the cisterns/sulci
-worst headache of my life, fever and nuchal rigidity may be present. But focal neurological deficits are usually absent.

40
Q

Uterine leiomyoma

A

Monoclonal tumors.
They can be located on serosal surface of uterus, within the uterine wall and below endometrium.
-subserosal fibroids often demonstrate exaggerated irregularity compared to intramural or submucosal fibroids, which are more constrained by uterine tissue.
- irregular uterine enlargment from fibroids can lead to bulk related symptoms —> pressure on colon —> constipation , pressure on adjacent organs —> urinary symptoms such as urgency or incomplete emptying.

41
Q

Immediate changes after treating B12 anemia

A

After giving cobolamin . The rate of effective erythropoiesis increases, however immature erythrocytes are released from bone marrow to blood stream. The count begins to rise within 3-4 days and peaks around 1 week. After a while their levels declines

Usmle (45 decks)

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