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Usmle > Block 12 > Flashcards

Block 12 Flashcards

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USMLE® Step 1 flashcards
1
Q

Patient with factor VII deficiency –. Given VITAMIN K –> doesnt improve why

A
  • vitamin K is responsible of carboxylation of factor VII not production of it . Factor VII is produced by the liver
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2
Q

Rett syndrome

A

X-lined dominant disorder affecting females( affected males die in utero) that presents in early childhood with progressive neurodegeneration and stereotypical hand movments.

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3
Q

Antibodies against presynaptic calcium channel

A

Lambert eaton syndrome

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4
Q

filtration fraction

A

GFR/RPF

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5
Q

Uv light effect on vit D(which process)

A

7-dehydrocholesterol –> cholecalciferol

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6
Q

QRS complex on ventricular deplorization (which phase)

A

Phase 0

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7
Q

Alanine function

A
  • its a major amino acid responsible for transferring nitrogen to the liver for disposal. During catabolism of proteins, amino group are transferred to å-ketoglutarate to form glutamate. –> forming urea the primary disposal form of nitrogen in humans.
  • in the liver alanine is transmitted by ALAT to pyruvate with the amino-group being transferred to å-ketoglutarate to form glutamate.
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8
Q

Dizygotic twins results in (di/di or mono/di)

A

Dichorionic diamniotic - because 2 ovum are fertilized= 2 implantations.

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9
Q

Antibodies in mysthenia gravis against

A

Autoantibodies against nicotinc actylcholine receptors on the postsynaptic membrane of the neuromuscular junction.

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10
Q

Treatment of black eschar (b.anthrax)

A

Ciprofloxacin

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11
Q

Maternal tobacco use

A

Impairs feta oxygenation, alter fetal development and response and eposes the fetus to multiple toxins –> detrimental outcomes include abnormal placentation(previa, abruption), prematurity, perinatal mortality and significantly reduced birth weight.

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12
Q

Neuroleptic malignant syndrome
Signs
Treatment

A
  1. Diffuse muscle rigidty
  2. High fever
  3. Autonomic instability (hypertension, tachycardia)
  4. Altered sensorium
  5. Creatine kinase elevation –> rhambdomyelesis.
    Treatment: cessation of drug, supporative and “dantrolene”, also bromcriptine in some cases
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13
Q

Erythropoietin produced by

A

Renal peritubular cells

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14
Q

Focal seziure types :
Simple
Complex

A

Simple : no loss of consciousness or postictal state, motor, sensory autonomic or psychic symptoms
Complex: loss of consciousness, may have have automatisms (lip smackin)
treatment :
1. Carbamazepine
2. Gabapentin
3. Phenobarbital
4. Phenytoin

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15
Q

11ß hydroxylase deficiency is

A
  • second most common cause of congeintal adrenal hyperplasia
  • its reponsible of conversion to cortisol.
  • leads to accumulation of 11-deoxycoricosteron (weak minaralocroticoids) –> low renin hypertension , hypokalemia.
  • cycle shift towards androgen synthesis
  • female ambigious genetalia
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16
Q

Heme synthesis in the cell (which organelle)

A

Mitochondria. Its necessary for the first and final 3 steps .

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17
Q

Galactosemia is (genitics)

A

AR disorder

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18
Q

How are RNA primers removed after replication

A

In eukaryotic: RNAase H
In prokaryotic: by DNA polymerase I as it can remove RNA primer (5’ exonuclease) and synthesize new DNA, begining at 3’ end of neighboring okazaki fragment.

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19
Q

Actinomyces israelii

A
  • patients usually complain of slow growing mass that began in the setting of oral trauma and has recently drains yellow pus.
  • gram positive component of normal oral flora
  • can cause cervicofacial actinomycosis, which is characterized by the formation of chronic face and neck abscesses complicated by cutaneous sinus tracts.
  • treatment - long course of parenteral penicillin and surgical deberdiment
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20
Q

Medial band like calcification

A

Monckebergs medial calcific sclerosis or media calcinosis.

Asymptomatic usually

21
Q

Secondhand smoke exposure

A

Risks of secondhand smoke exposure:

  1. Prematurity
  2. Sudden infant death syndrome
  3. Middle ear disease
  4. Asthma
  5. respiratory tract infection.
22
Q

Type II pneumocytes

A

Make up more than half of total number of alveolar cells.

  • they are the source of pulmonary surfactant and have the ability to proliferate in response to injury.
  • they also acts as progenitor cells for type I pneumcytes which cant regenerate on their own.
23
Q

Monozygotic twining separation at what day

A

0-4 days : dichorionic diamniotic
4-8: monochorionic diamniotic
8-12: monochorionic monoamniotic
>13 : conjoined twins

24
Q

Bronchiolitis

A

AGE: <2 , RSV most common cause
Clinical :
-antecedent nasal congestion/ discharge and cough
-wheezing, crackles and respiratory distress (tachypnea,retractions and nasal flaring)
-apnea in high risk patients

25
Q

Procarcinogenic substances metabolism

A
  • pro-carcinogenic substances are metabolized by CP450 monooxygenase.
  • cytochrome monoxygenease is responsible for metabolism of steroids alcohol, toxins and other foreign substances by rendering them soluble and easier to excrete.
26
Q

Muscle pain with exercise that remits with rest

A

Intermittent claudication .

  • its almost always due to ATH of the arteries (lipid filled intimal plaque that bulge into the arterial lumen).
  • thigh claudication is suggestive of occlusive disease of ipsilateral external illiac, or common femoral and/or both the superficial femoral and profounda femoral.
27
Q

Internuclear opthalmoplegia

A
  • disorder of conjugate horizontal gaze resulting from damage to the heavily myelinated fibers of MLF.
  • MLF is paired neural tract that mediates communication between CNIII and CN VI nuclei allowing for coordinated horizontal eye movement.
  • unilateral MLF lesions can occur with lacunar stroke in the pontine artery distribution, although bilateral lesion are classicaly seen in MS.
  • lesion in left dorsal pons –> disrupt MLF –> impaired adduction of ipsilateral eye (left) during right conjugate horizontal gaze.
  • convergence is usually preserved .
28
Q

Esophageal squamous cell carcinoma: histology

A
  • solid nest of neoplastic squamous cell with abundant eosinophilic cytoplasm.
  • distinct borders
  • areas of keratinization are easlily seen (keratin pearls) and presence of intercellular bridges.
29
Q

Activation of pancreatic enzymes

A
  • most are synthesized by pancreatic acinar cells as precurosr called “zymogens”
  • they are secreted from the apical surface of the acinar cell into the lumen.
  • after traversing pancreatic duct system –> ampulla of vater –> 2nd part of dudenum.
  • enterokinase convertes trypsinogen to typsin which is responsible for activation of other zymogens including chymotrypsin, elsastase and carboxypeptidase.
  • also it cleaves trypsinogen –> trypsin (trypsin makes tyrpsin)
30
Q

Why ß blockers and nitrates sometime given together

A
  1. To prevent reflex tachycardia

2. Decrease cardiac work by mechanism different of nitrates

31
Q

Piriform recess

A

Small cavities that lies on either side of laryngeal orifice, bound medially by aryepiglottic folds and laterally by thyroid cartilage and thyrohyoid membrane.

  • a thin layer of mucosa overlying the piriform recess is all that protects superfacial coursing internal laryngeal nerve – branch of superior laryngeal nerve (CN X).
  • the internal laryngeal nerve involved in cough reflex
32
Q

Prior history of MI –>

A

Lower risk of cardiac rupture due to the presence of myocardial fibrosis at the site of infarction and development of coronary collateral circulation

33
Q

Club cells

A

Nonciliated secretory cells found in the terminal portion of bronchioles(not alveoli) they act as regenerative source of ciliated cells in the bronchioles.

34
Q

Carbamazepine
mechanism of action
Side effects

A

Mechanism = Neuroleptic medication that inhibits neuronal high frequency firing by reducing the ability of sodium channels to recover from inactivation.

Side effects= bone marrow suppression –> anemia, agranulocytosis and thrombocytopenia., as well as it can lead to SIADH.

35
Q

Dantrolene

A

Used in neuroleptic malginant syndrome
Its a direct skeletal muscle relaxant. It can reduce muscle rigidity/ contraction by antagonizing the Ryanondine receptos –> inhibit Ca++ ion release from SR of skeletal muscle.

36
Q

Columnar Ciliated cells in the alveolar ducts and sacs

A

(Pseudstratified ciliated coulmnar epithelium)They are absent – replaced by simple ciliated cuboidal cells at the level of terminal bronchioles.

37
Q

Ureteral obstruction – changes in GFR

A

GFR depends on the interplay between hydrostatic and oncotic pressure in the GFR and bowmans space. The GFR increase with higher glomerular hydrostatic pressure and decreases with increasing bowmans capsule hydrostatic pressure or higher glomerular capillary oncotic pressure.
- acute ureteral obstruction leads to increase hydrostatic pressure proximal to the constiction –> decreased GFR due to high hydrostatic pressure in bowmans capsule.

38
Q

Nitrates free interval

A

Around the clock nitrate administration leads to development of tolerance to nitrates. This is why nitrate free interval must be provided every day in patients that are using long acting nitrates (isosorbide dinitrate).

39
Q

If lyzozomal acification wernt functional in APC–>

A

antigen processing in association with MHC class II antigens would not occur, and MHC class II would be unable to bind antigen and therefore unable to bind TCR.

40
Q

Surfactant is

A

Stored and transported to cell surface by lamellar bodies. Normally released by exocytosis into alveolar spaces, where the lamellar contents inravels and spread along the alveolar lining.
-it facilitate lung expansion during respiration.(opposing atelectasis).

41
Q

Generalized seizures:
Tonic clonic
Myoclonic
Absence

A
  1. Tonic clonic: loss of consciousness, diffuse muscle contraction of limbs (tonic) followed by rhythmic jerking (colonic).
  2. ## Myoclonic: no loss of consciousness, brief jerking movementBoth of these conditions are treated using broad spectrum such as lamotrigine, levetiractem, topiramate and valproic acid.
    —-
    Absence seizures: brief loss of consiousness, may have automatism and usually no postictal state
    Treatment : ethosuximide.
42
Q

Pathogenesis of acute pancreatitis

A
  • premature activation of trypsin inside the pancreatic acini.
  • direct parynchemal injury(alcohol,iatrogenic etc…) or ductal obsturction (gallstone, tumors) —> acinar cell dysfunction–> intracinar trypsinogen activation —>activation and release of other pancreatic autodigestive enzymes —>results in:
    1. Fat necrosis
    2. Pancreatic inflammation and destruction
    3. Vascular damage and hemorrhage.
43
Q

Bacteria that needs cholesterol to grow on a culture

A

M.pneumoniae

44
Q

TNF-alpha inhibitors can predispose to

A
  • reactivation of latent M.TB–> increased risk for disseminated disease.
  • tuberculin skin test should be done prior
45
Q

Congenital pyloric stenosis

A
  • right upper deep olive like mass
  • non-bilious vomiting.
  • hypertrophy of pyloric muscularis mucosa
  • (smooth muscle hypertrophy)
46
Q

Enlarged superfacial inguinal lymph nodes

A

These nodes overlies femoral nerve, artery, and vein in the femoral triangle, a region bound by the inguinal ligament, sartorius muscle and adductor longus muscle.
-Inguinal lymphadenopathy with malignancy is due to malignancy around the orifice of the anal canal.

47
Q

Secretin

A
  • hormone secreted by interstitial S cells
  • increase HCO3- secretion from pancreas, with low chloride
  • secreted in response to food due to the low acidity of food leaving the stomach
48
Q

Huntington disease
Pathogenesis,subsequent generation inheritence
Clinical
Treatment

A
  • during spermatogenesis, CAG repeats (the larger the repeats the more severe the disease) in abnormal HTT gene (chromosome 4p) can rapidly increase, much more than during oogenesis.
  • therefore patients who receives abnormal gene from their fathers tend to develop the disease earlier in life.
  • the tendency of clinical symptoms to worsen and occur earlier in subsequent generation called anticipation.
  • clinical: 1. Movement disorder(chorea) ,2. Behavioral abnormalities (apathy,depression or aggressiveness) 3. Dementia

Usmle (45 decks)

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