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Uworld practice test 1 Flashcards

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1
Q

Cardiac tissue conduction velocity

A
  • Fastest to slowest (Park At Venture Avenue)
    • Purkinje (bundle of his and LandR BB along interventricular septum 2.2 m/s)
    • Atrial (SA node 1.1 m/s located at R atrial wall near SVC)
    • Ventricular (0.3 m/s) myocardium
    • AV node (0.5 m/s located at interatrial septum near tricuspid orifice)
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2
Q

this is caused by neuro conditions, such as MS, and is characterized by dysarthria, dysphagia, dysphonia, and impaired movement of the tongue and facial muscles

A

pseudobulbar palsy

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3
Q

The appearance of DNA fragments in multiples of 180 base pairs on gel electrophoresis is known as …

This finding is a sensitive indicator of …

A

DNA laddering

apoptosis

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4
Q

What are ssx of anticholinergic toxicity?

A
  • hot as a hare
    • increased body temp
    • decreased sweating, decreased heat dissipation
  • dry as a bone
    • decreased secretions (eg mucous membranes, sweat glands)
    • decrease glandular secretion and smooth muscle contraction
  • red as a beat
    • flushed skin
    • superficial vasodilation from increased body heat
  • blind as a bat
    • cycloplegia, mydriasis
    • paralysis of ciliary muscle and iris sphincter
  • mad as a hatter
    • AMS
    • permeates BBB
  • full as a flask
    • urinary retention and constipation
    • decreased detrusor muscle contraction and decreased internal urethral sphincter relaxation; decreased smooth muscle contraction
  • fast as a fiddle
    • tachycardia
    • decreased vagal tone at SA node
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5
Q

What type of mosiacism should be considered when a genetic mutation is identified in the offspring but not in the parents?

A

Germline mosaicisim - involves only oocytes or spermatocytes

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6
Q

Somatic mutations cannot be…

A

passed on to offspring

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7
Q

What cytokine is produced exclusively by lymphocytes?

A

IL-2 - functions to stimulate growth and differentiation of T cells, B cells, NK cells, and macrophages

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8
Q

What cells make each cytokine?

IL-1

TNFa

IFNa

GM-CSF

A
  • IL-1 - mononuclear phagocytes
  • TNFa - activated macrophages
  • INFa - monocytes, macrophages, B cells, NK cells
  • GM-CSF - macrophages, T cells, NK cells, mast cells, endothelial cells, and fibroblasts
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9
Q

adehesion molecules that bind epithelial cells together within tissues

A

Cadherins (eg desmogleins, desmocollins, E-cadherin)

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10
Q

externally, cadherin molecules on epithelial cells bind to cadherin molecules on adjacent cells to form

A

adherens junctions and desmosomes

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11
Q

cell adhesion to the basement membrane is mediated primarily by

A

hemidesmosomes

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12
Q

molluscum bodies on micro are…

A

large eosinophilic cytoplasmic inclusions made of virus particles

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13
Q

In posterior and anterior knee dislocations, what structure is most at risk for injury?

A

popliteal artery bc it is deep within the popliteal fossa, close to the articular surfaces of the joint

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14
Q

mature defense mechanism in which the person channels impulses into socially acceptable behaviors

A

sublimation

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15
Q

What does heminephrectomy do to GFR?

A

acute reduction of total GFR by 50%, but nephrons in remaining kidney undergo significant hemodynamic and structural adaptations to allow for the single nephron GFR to rise

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16
Q

NNT and ARR equation

A

NNT = 1-ARR

ARR = Control rate - Treatment rate

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17
Q

Acute intermittent porphyria is due to

A

an autosomal dominant defect in porphobilinogen (PBG) deaminase

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18
Q

What physical change occurs with myasthenia gravis?

A

thymic hyperplasia or thymomas

ptosis possible

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19
Q

Metabolic derangements of DKA include…

A
  • metabolic acidosis
  • ketonemia
  • hyperglycemia
  • hyperkalemia
  • hyponatremia
  • hyperammonemia can also be observed due to muscle degradation
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20
Q

Complete androgen insensitivity syndrome v Mullerian Agenesis

A
  • AIS
    • X linked mutation of androgen receptor
    • normal breast development
    • absent uterus and upper vagina; cryptorchid testes
    • minimal to absent axillary and pubic hair
    • karyotype 46, XY
  • Mullerian Agenesis
    • hypoplastic or absent mullerian ductal system
    • normal breast development
    • absent or rudimentary uterus and upper vagina; normal ovaries
    • karotype 46, XX
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21
Q

Premature infants are at significant risk for interventricular hemorrhage, aka

what is this area?

A

germinal matrix hemorrhage

germinal matrix is a dense cellular and vascular layer of the subenpendymal zone of the brain from which neurons and glial cells develop in utero

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22
Q

When does the germinal matrix normally begin to involute?

Germinal matrix hemorrhage begins between the what structures and extends to where?

A

begins to involute by 28 weeks gestation and is absent by term

begins betweent he caudate nucleus and the thalamus, then extends into the lateral, third, and fourth ventricles - resulting in hydrocephalus and bulging fontanelles

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23
Q

Misoprostol MOA

A

prostaglandin E1 analog (receptor agonist) that can be used to prevent or tx NSAID induced gastritis and peptic ulcer formation

decrease acid secretion by parietal cells through the inhibition of the downstream messenger cAMP, which normally stimulates acid formation

can also cause uterine contractions and cervical ripening

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24
Q

What are the effects of nitrates when treating angina?

A

direct vascular smooth muscle relaxation, causes systemic venodilation and decreased peripheral venous return

lowers end-diastolic LV volume and pressure (decreased preload), which reduces myocardial oxygen demand by decreasing systolic wall stress

leads to reflex tachycardia

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25
autosomal dominant form of pseudohypoparathyroidism associated with skeletal defects (eg short stature, short metacarpal and metatarsal bones); caused by defects in GNAS1, which codes for the alpha subunit of the G protein (Gsa) that mediates the effects of PTH dx?
Albright hereditary osteodystrophy
26
What causes DNA loops?
RNA splicing introns of a gene are removed from pre-mRNA for protein translation to occur, then mRNa only binds with DNA in correct areas, leaving the rest of DNA looped
27
instances when different mutations at the same genetic locus cause similar phenotypes
allelic heterogeneity (more than one type of mutation is possible at a given gene but can cause the same disease)
28
interactions between multiple genes that combines to create a new phenotype or mask/modify the phenotype of one of the genes is called... what is an example?
epistasis pt with SCA who also has a mutation causing persistence of high fetal hemoglobin causing a less severe course
29
Steps of ELISA
1. a known antigen is fixed to surface of a well 2. pt serum added; if present, antigen-specific abs bind the antigen and remian fixed to the well. Plate is washed to removed unbound 3. anti-human ig ab coupled to a substrate-modifying enzyme (eg peroxidase) is then added; this ab-enzyme conjugate binds to antigen-bound abs in the wells. plate is washed again 4. substrate which is modified by the enzyme to elicit a detectable signal such as a color change, is added. If the assay is quantitative, the intensity of color change is proportional to the amount of antibody present in the pts serum
30
What is BTK molecule and what does it do? dx?
Bruton's tyrosine kinase important in the maturation of B cells; without it, B cells cannot leave the bone marrow to enter circulation, and antibodies are not produced X linked Agammaglobulinemia
31
proteins destined for the endoplasmic reticulum possess what in order to identify themselves as such?
N-terminal peptide signal sequences
32
defect in branched-chain alpha-keto acid dehydrogenase complex resutling in an inability to degrade branched chain alpha-amino acids (leucine, isoleucine, and valine) and their alpha-ketoacid metabolites what disorder? what does this enzyme require as a cofactor?
maple syrup urine disease requires thiamine as a cofactor
33
What maintains the high local concentration of testosterone necessary for normal sperm production and maturation?
androgen-binding protein (ABP) synthesized by Sertoli cells of the seminiferous tubules
34
pulmonary arterial hypertension results from what?
pulmonary arterial endothelial dysfunction; small pulmonary arteries and arterioles undergo hypertrophy of the smooth muscle medial layer and hyperplasia of the intimal layer, followed by progressive intimal fibrosis with eventual development of plexiform lesions
35
alveolar hyaline membrane formation occurs in
acute respiratory distress syndrome, which typically occurs in the setting of acute illness
36
what is the MC uterine fibroid symptom? what is this from?
heavy menstrual bleeding may result from impaired contractility, increased uterine surface area, and ulceration of endometrium over a submucosal fibroid; fibroids also cause venous ectasia (dilation)
37
mucosal hemorrhage and patchy areas of necrosis seen on colonoscopy visualizing the rectum, sigmoid, and portion of descending colon are consistent with
ischemic colitis
38
hypoglycemia after prolonged fasting with inappropriately low ketone bodies suggests
impaired beta oxidation medium chain acyl-CoA dehydrogenase deficiency is the most common genetic defect in beta oxidation
39
carcinoid tumors stain positive for what?
neuropeptides such as chromogranin and synaptophysin
40
Eukaryotic translation is initiated when the small ribosomal
41
rod-shaped intracytoplasmic crystal-like inclusions with rounded ends within stromal cells, located in the interstitial cells of the testis
Reinke crystals seen in Leydig cell tumors
42
Clearance of a drug calculation
CL = (0.693 xVd)/t1/2
43
What accumulates in alkaptonuria? why would this happen?
homogentisate (homogentisic acid) accumulates in tissues, blood, and urine AR disorder due to a deficiency of homogentisate 1,2 dioxygenase (HGA oxidase), the third enzyme in tyrosine degradation
44
first line treatment for abnormal uterine bleeding due to anovulation
combined OCP
45
Hypoglycemia after prolonged fasting with inappropriately low ketone bodies suggests
impaired beta oxydation
46
carcinoid tumors will stain positive for what?
chromogranin and synaptophysin
47
eukaryotic translation is initiated when the small ribosomal subunit binds the 5' cap of mRNA and scans for AUG start codone within ... this is facililated by a family of proteins known as
the Kozak consensus sequence eukaryotic initiation factors (eIFs)
48
eIFs are degraded during apoptosis, so many proteins necessary for apoptosis are translated using an laternative method known as...
internal ribosome entry a distinct nucleotide sequence called the internal ribosome entry site (IRES) attracts the eukaryotic ribosome to mRNA and allows translation to begin in the middle of the mRNA sequence
49
What happens in Li-Fraumeni syndrome?
germline inactivating mutation in p53 is present in every cell in a pts body; a second hit or mutation in a single somatic cell renders the reminaing p53 gene nonfunctional, leading to unchecked proliferation of mutated cells and carcinogenesis
50
What are the intrinsic muscles of the larynx responsible for sound production? Which are innervated by the recurrent laryngeal nerves?
**posterior and lateral cricoarytenoids, oblique and transverse arytenoids, thyroarytenoids**, cricothyroid first ones are innervated
51
Among primary sensory afferent fibers, those responsible for what functions are unmyelinated?
slow pain, heat sensation, and olfaction are unmyelinated
52
what is the measure of variability around the mean? The larger the sample size...
standard error the smaller the SE
53
During antigen processing in macrophages, the ..... is removed from the MHC-invariant complex and replaced by an external protein. This MHC-peptide complex (containing .........) is then expressed at the cell surface.
invariant chain an alpha-chain, beta-chain, and external protein
54
What are the chromosome 15 genomic imprinting disorders?
* Prader-Willi * loss of paternally inherited allele * neonatal hypotonia * hyperphagia/obestity * hypogonadism * Angelman Syndrome * loss of maternally inherited allele * epilepsy/sz * ataxic gait/tremors * inappropriate laughter/smiling
55
Cellular differentiation is determined by....
transcription factors all nucleated cells in humans possess the entire genome, but tissue-specific transcription factors allow only for the expression of genes that are relevant for a particular cell type
56
what does pilocarpine do?
direct cholinergic muscarinic agonist constricts the pupil via the muscarinic receptors of the smooth muscle of the pupillary sphincter
57
What results due to long standing pernicious anemia?
* atrophic glossitis, causing profound hypochlorhydia * leading to a compensatory increase in serum gastrin levels (antral G cells no longer inhibited) * loss of intrinsic factor-secreting parietal cells * leads to depletion of B12 * hematologic and neurologic manifestations
58
What kind of testicular enlargement might disappear with recumbency and does not transilluminate?
varicocele
59
cystic mass that arises from the caput of the epididymis and generally do not cause symptoms
spermatocele
60
What type of long term anticoagulation is recommended in patients with mechanical heart valves to reduce the risk of thromboembolic complications?
vit K antagonist/warfarin
61
Absence of CD40 ligand is diagnostic for
hyper-IgM syndrome
62
Clinical features of this disease include splenomegaly, which can lead to pancytopenia, due to rapid splenic destruction of blood cells, and skeletal destruction, which can lead to severe bone pain and avascular necrosis
Gaucher disease Beta-glucocerebrosidase deficiency
63
What does stimulation of alpha-1 adrenergic receptors by catecholamines result in?
results in Gq protein activation and initiation of the phosphatidylinositol second messenger system
64
ubiquitous fungal organism whose reproductive forms classically exhibit a "broom-like" structure on silver staining
Aspergillus
65
process by which bacteria take up naked DNA from the environment bacteria that are able to take up foreign DNA and incorporate it into their own genome are referred to as... ex?
transformation competent Haemophilus, Streptococcus, Bacillus, Neisseria
66
Focal segmental glomerulosclerosis is often seen in what conditions?
HIV infection (HIV associated nephropathy), heroin addiction, and sickle cell disease
67
What is characteristic of HIV nephropathy?
collapsing glomerulonephropathy, a variant of FSGS the usual FSGS lesions are seen in addition to the collapse and sclerosis of the whole glomerular tuft; glomerular epithelial cells tend to proliferate and hypertrophy, and marked tubular injury with accompanying microcyst formation
68
What do aquaporin-2 water channels do?
water is reabsorbed through these channels that span the luminal membrane to allow for osmotic equilibration with the surrounding hypertonic interstitium when ADH tells them to retain water
69
When does highest contraction velocity occur in skeletal muscle?
when the afterload is zero
70
What does thermal cycling PCR involve?
heating for DNA strand denaturation, cooling for primer hybridization, and rewarming for primer extension and DNA synthesis

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