UWorld Practice Test #1 Flashcards
1
Q
How is diabetic nephropathy characterized histologically? What if the sclerosis is nodular in nature?
A
Mesangial expansion, glomerular basement membrane thickening and glomerular sclerosis. If sclerosis is nodular in nature, this is called and Kimmelstiel-Wilson lesion.
2
Q
Order atrial muscle, ventricular muscle, the purkinje system and the AV node from fastest to slowest in terms of conduction velocity?
A
Fastest to slowest: purkinje –> atrial muscle –> ventricular muscle –> AV node.
3
Q
Where is the AV node located?
A
Along the interatrial septum, near the tricuspid orifice.
4
Q
What bone tumor is most commonly associated w/ Paget’s disease?
A
Osteosarcoma.
5
Q
Where does osteosarcoma like to occur and what is the typical radiographic pattern?
A
Likes to occur at the metaphysis of long bones (femur, humerus, tibia, etc.). Radiography shows mixed radiodense and radiolucent areas, periosteal new bone formation, lifting of the cortex, Codman’s triangle, and the adjacent soft tissue may have a sunburst pattern on X-ray.
6
Q
What is globus sensation?
A
It is the abnormal feeling of foreign body, tightness or fullness of the throat that does not have accompanying physical, endoscopic or radiographic findings of esophageal obstruction.
7
Q
What characterized pseudobulbar palsy and what causes it?
A
Characterized by dysarthria, dysphagia, dysphonia and impaired movement of the tongue and facial muscles.
Caused by neurologic disorders like MS.
8
Q
What is it called when there is endometrial stroma and glands in the myometrium of the uterus? How about outside the uterus?
A
In myometrium –> adenomyosis
Outside –> endometriosis
9
Q
What is DNA laddering and what does it indicate?
A
DNA laddering is seeing 180bp segments of DNA on gel electrophoresis of cells. It indicates DNA is being broken up by endonucleases as part of karyorrhexis, and that the cells are undergoing apoptosis.
10
Q
What does BLC2 do? Name a malignancy that commonly over expresses it.
A
BCL2 is an anti-apoptotic protein that helps the cell resist apoptosis. It is commonly overexpressed in follicular lymphoma due to the 14;18 translocation that is common.
11
Q
Define pleiotropy
A
Pleiotropy = the occurrence of multiple, seemingly unrelated phenotypic manifestations, often in different organ systems, as a result of a single gene mutation.
12
Q
It is important to recommend what daily activity to diabetic patients?
A
Foot inspection.
13
Q
What translocation causes APML (see Auer rods on histo)
A
15;17
14
Q
What is the function of IL-2 and what produces it?
A
Produced exclusively by antigen stimulated T lymphocytes. It stimulates growth and differentiation of T cells, B cells, NK cells and macrophages. Binding in an autocrine fashion stimulates clonal proliferation of the T cells.
15
Q
What is the function of IL-1 and what produces it?
A
IL-1 is produced mainly by mononuclear phagocytes. It functions to activate lymphocytes and is associated w/ systemic illness changes like fever, anorexia, lethargy, etc.
16
Q
______ is produced by activated macrophages and induces the systemic inflammatory response.
A
TNF-alpha.
17
Q
______ are adhesion molecules that bind epithelial cells together within tissues.
A
Cadherins.
18
Q
What sort of protein are fibronectins and laminins?
A
They are extracellular matrix glycoproteins that, through binding to integrins, facilitate cell binding to the extracellular matrix.
19
Q
What causes molluscum contagiosum?
A
Poxvirus
20
Q
Grossly, what do the lesions of molluscum contagiosum look like? Microscopically?
A
Flesh colored papules w/ central umbilication, commonly on the eyelids, face or trunk in children.
Microscopically see molluscum bodies which are eosinophilic viral inclusions.
21
Q
What is the most important RF for endometritis?
A
Cesarean delivery is biggest one due to introduction of microbes and foreign bodies into the incised uterus.
22
Q
What are some signs and sxs of post-partum endometritis?
A
Foul-smelling vaginal discharge, leukocytosis, fever and uterine tenderness.
23
Q
How does nummular eczema present?
A
W/ coin-shaped, pruritic, erythematous patches.
24
Q
Describe the coping mechanism of displacement?
A
Where feelings associated w/ one person or situation are inappropriately shifted to another.
25
The coping mechanism of _______ is where you attribute your thoughts or feelings to another person?
Projection
26
In the defense mechanism of _______, intense, unacceptable feelings are transformed into their opposites.
Reaction formation --> it is basically responding in a manner that is the opposite of one's true feelings.
27
Ligand binding to the extracellular portion of a receptor tyrosine kinase causes what?
Dimerization of 2 identical receptor subunits.
28
A patient w/ headaches, chronic nasal discharge, atrophic nasal mucosa, and a perforated nasal septum increases your suspicion for what?
Habitual cocaine abuse.
29
Acutely after a heminephrectomy (removal of one kidney) the GFR is _____% from baseline. After about 6 weeks the GFR is ____% of baseline.
Initially --> 50%
6 weeks later --> 80%
30
What is the site of action of phosphodiesterase-5 inhibitors like sildenafil?
Vascular smooth muscle of the corpora cavernosa of the penis
31
Paralysis of the _______ results in an inability to raise the arm overhead and protrusion ("winging") of the medial border of the scapula when the outstretched arm is pushed against resistance.
Serratus anterior
32
The ______ nerve innervates serratus anterior. The function of this muscle is to ______?
long thoracic nerve
stabilizes and rotates the scapula upward
33
What is the function of the levator scapulae? What innervates it?
It elevates the scapula and rotates the glenoid fossa inferiorly. Innervated by the 3rd and 4th cervical spinal nerves as well as the dorsal scapular nerve.
34
The trapezius ______ and ______ the scapula.
Elevates and retracts
35
Define schizophreniform disorder
Same sxs as schizophrenia that have been present for at least one month but no more than 6 months, and functional decline is not required whereas for schizophrenia it is.
36
What enzyme has a defect in acute intermittent porphyria?
Porphobilinogen deaminase. It catalyzes the step from porphobilinogen to hydroxymethylbilane.
37
What causes porphyria cutanea tarda?
uroporphyrinogen decarboxylase deficiency.
38
What tumor is myasthenia gravis associated with?
Thymoma
39
In addition to retinoblastoma, what is another malignancy that patients with familial retinoblastoma are at risk for?
Osteosarcoma
40
Absence of IgG (i.e. from hyper IgM syndrome where there is a CD40 defect) predisposes pts to what sorts of infections?
Infections w/ encapsulated pathogens.
41
In DKA, by how many mEq does the serum Na drop for every increase in 100 mg/dL of glucose?
1.6mEq
42
What is a dandy-walker malformation?
Aplasia or hypoplasia of the cerebellar vermis and cystic dilation of the 4th ventricle w/ enlargement of the posterior fossa.
43
What is syringobulbia?
A fluid filled cavity in the lower brainstem.
44
How do patients with complete androgen insensitivity syndrome present and what is the pathogenesis?
They will have minimal to no axillary or pubic hair, a vagina ending in a blind pouch w/ absence of uterus or upper vagina, and will have cryptorchid testes. Still get breast development.
There is an X-linked mutation to the androgen receptor such that it is insensitive to androgen.
45
What is the hallmark lab finding in 5alpha-reductase deficiency?
elevated testosterone:DHT ratio
46
Why are premature infants susceptible to interventricular hemorrhage?
Because the germinal matrix (located interventricularly) doesn't start to involute until 28 weeks gestation and is absent by term. AND, the germinal matrix has a vascular network that is weak and lacks support such that it is more susceptible to hemorrhage.
47
The vast majority of the cancers in the head and next are _________?
Squamous cell carcinomas.
48
The chloride channel encoded by the CFTR gene, which is mutated in CF, promotes _______ of Cl at the respiratory epithelium and ______ of Cl at the sweat ducts?
Extrusion of Cl at respiratory epithelium.
Resorption of Cl at sweat ducts.
49
What is allelic heterogeneity?
It is where different mutations at the same genetic locus cause similar phenotypes.
50
What is epistasis?
Where the interaction between multiple genes comes together to produce a new phenotype or to modify/mask the effect of other genes?
51
True or false, clemastine, an H1 receptor antagonist, is effective in the treatment or prevention of asthma?
False! Even though histamine is a mediator of asthma sxs, tx w/ clemastine is NOT effective.
52
What may clemastine be used to treat?
Allergic rhinitis and uticaria.
53
How does leukotriene D4 contribute to asthma pathogenesis?
induces bronchospasm and increases bronchial mucus production
54
What is the most common mechanism of drug efflux pumps in bacteria?
The pump is a cotransporter that movers H+ out of the bacterium down its concentration gradient and simultaneously moves the antibiotic out of the cell, against its concentration gradient.
55
What gene is most commonly mutated in osteogenesis imperfecta?
COL1A1 leading to defect in type 1 collagen.
56
Describe the nature of signal sequences that cause protein translation to move to the RER (i.e. the case of insulin).
The signal sequences are 15-20 amino acids that are mostly hydrophobic in nature. They are recognized by SRPs (signal recognition particles).
57
What enzyme is deficient/dysfunctional in MSUD?
Branched chain amino acid decarboxylase aka alpha-ketoacid dehydrogenase?
58
Name a couple of enzymes for which thiamine is a coenzyme
Alpha-ketoacid dehydrogenase and transketolase.
59
What sort of RBCs can be seen in thalassemia?
microcytic, hypochromic RBCs
60
Which cell in the testes makes androgen binding protein?
Sertoli cells
61
How are relatively high levels of androgens maintained in the seminiferous tubules?
Androgen binding protein binds to testosterone and dihydrotestosterone which makes them less lipophilic and thus less likely to diffuse out of the luminal fluid.
62
Which G protein subunit does glucagon binding act thru?
Gs
63
To surgically disrupt hyperhidrosis of the axilla, what structure should you interrupt?
The thoracic sympathetic trunk. Note that sweating is a function of the sympathetic NS.
64
What is the predominant collagen found in hyaline cartilage?
Type II collagen
65
In females, what do the superior and inferior portions of the gubernaculum become respectively?
Superior --> proper ovarian ligament, which connects the uterus to the ovary.
Inferior --> round ligament of the uterus. Descends thru the inguinal canal and connects to the labia majora.
66
Why do patients w/ a PE have alkalosis?
They have V/Q mismatch which causes the body to hyperventilate to try and compensate for the mismatch and the resultant hypoxemia. This lowers PCO2 and raises the blood pH. However, it doesn't compensate entirely for the hypoxemia so PO2 is still low.
67
What is the inciting issue in idiopathic pulmonary hypertension?
Some sort of endothelial damage. The basis of the pathogenesis is endothelial dysfunction.
68
Histologic findings in idiopathic pulmonary hypertension are?
Thickening of the endothelium, smooth muscle and intimal cells in conjunction with concentric laminar intimal fibrosis.
69
What is the most common uterine fibroid sx?
Heavy menstrual bleeding
70
Why do the sclera appear blue in osteogenesis imperfecta?
There is decreased collagen content in the sclera which makes sclera thin and translucent and makes the underlying choroid layer more easily visualized.
71
What is the most common genetic defect of beta oxidation?
Medium chain acyl-CoA dehydrogenase deficiency
72
What is the function of RAS? How does it do this?
RAS is an oncogene (it acquires gain of function mutations that are oncogenic). How it works is it transduces signal from the cell surface receptor to the nucleus to promote mitogenesis.
73
RAS is part of the _______ signaling system
MAP-Kinase
74
The GTP form of RAS is _______, whereas the GDP containing form is _______?
GTP --> active
GDP --> inactive
75
On a Lineweaver-Burke plot of enzyme kinetics (where Y represents I/V and X represents 1/[S]), what is the slope, y intercept and x intercept?
```
slope = Km/Vmax
y-intercept = 1/Vmax
x-intercept = -1/Km
```
Recall Km = [S] at 1/2Vmax
76
True or false, young age is considered a significant RF for osteoarthritis?
FALSE! Old age is a highly signficant RF for OA though!
77
What is the mechanism of action in octreotide treatment of carcinoid syndrome?
Medication reduces the secretion of bioactive peptides by the carcinoid tumor.
78
In eukaryotes, what is the start codon? What amino acid does it code for? Where must it be found in order for translation to start? What is an alternative method of initiating translation?
AUG = start codon. Codes for Methionine. It must be found within the Kozak consensus sequence.
Alternative method is by making use of internal ribosome entry. This may occur in apoptosis for example when the initiation factors for the above process have been degraded by proteases.
79
What is the function of the Shine-Delgarno sequence?
Helps initiate translation in prokaryotes.
80
Eukaryotes typically have ____ open reading frame(s) in an mRNA
one
81
What is the mechanism of action of thiazolidinediones?
The are peroxisome proliferator-activated receptor-y agonists. This increases the transcription of insulin responsive genes including increased GLUT4 and increased adiponectin (a cytokine secreted by fat tissue that increases the # of insulin responsive adipocytes).
82
What is the most frequently involved site in Crohns disease?
The terminal ileum.
83
Why does it take 3 days or so to see the full rise in PT from warfarin?
Because the half-life of factor II is approximately 3 days and full effect won't be seen until its levels are reduced.
84
What is the mechanism of action of lactulose in treating hepatic encephalopathy?
It is metabolized by gut bacteria to make acids. This acidification of the gut lumen converts NH3 there to NH4+. This in turn will draw more NH3 from the blood into the gut lumen by osmotic effect, and this reduces the blood levels of ammonia.
85
TMP/SMX inhibits or induces the CYP450 system?
Inhibits
86
In osteomalacia, there is decreased mineralization of what part of the bone?
There is decreased mineralization of osteoid.
87
Is bone pain seen in osteoporosis or osteomalacia?
Osteomalacia
88
What nerve innervates the cricothyroid muscle?
The external laryngeal nerve
89
What muscles does the recurrent laryngeal innervate?
Posterior and lateral cricoarytenoids, olblique and transverse arytenoids, and the thyroarytenoid.
90
Machine-like murmur over the upper precordium is associated with?
Patent ductus arteriosus.
91
Why does an ASD cause a fixed splitting of S2?
Because the L --> R shunt leads to R ventricular overload during diastole. This overload leads to delay in pulmonic valve closure which produces the splitting.
92
Name the important types of nerve fibers that are unmyelinated.
Postganglionic autonomic nervous system axons, afferent neurons conducting heat sensation, afferent neurons that transmit slow-onset dull, burning or visceral pain.
93
How long must delusions be present in order to make a dx of delusional disorder?
At least one delusion for at least one month.
94
What is the equation for standard error (SE)?
SE = std dvtn / square root of sample size (n)
95
What happens to the invariant chain in MHC class II molecules?
So initially these MHC class II molecules are synthesized w/ an alpha chain, beta chain and invariant chair in the RER. Then, this complex is moved to the endosome where the invariant chain is degraded by proteases, and is replaced by external protein to be presented.
96
Glossal pain, dry mouth, atrophy of the tongue papillae and alopecia are all signs of what?
Iron deficiency.
97
Greater than 80% of pts who get reactive arthritis carry what allele?
HLA-B27
98
Prader willi results from loss of ______ imprinted alleles on chromosome 15
paternally imprinted alleles
99
Celiac disease is associated w/ which alleles?
DQ2 and DQ8
100
What is the pathophysiology of dermatitis herpetiformis in Celiac disease?
Cross reaction of anti-gliadin IgA w/ transglutaminase in the dermal basement membrane.
101
What layer of skin is increased in thickness in a skin callus?
The stratum corneum of the epidermis.
102
What are FSH and LH levels typically in PCOS?
LH is generally high (stimulating high levels of testosterone causing hirsutism) whereas FSH is usually normal or low.
103
What enzyme is deficient in patients with Lesch-Nyhan syndrome and what part of the purine salvage pathway does it participate in?
X-linked recessive defect in hypoxanthine-guanine phosphoribosyltransferase, which participates in the salvage part of the pathway by catalyzing conversion of hypoxanthine and guanine to inosine monophosphate and guanosine monophosphate respectively.
104
How does tetracycline binding to the 30S subunit of ribosomes affect translation?
It prevents the aminoacyl-tRNA from entering the ribosomal acceptor site.
105
Cellular differentiation is determined by what?
The transcription factor milieu within an individual cell.
106
In terms of varicocele, what is meant by the "nutcracker effect"?
It helps explain why the majority of these occur in the left testicle. The L testicular vein drains into the L renal vein (as opposed to the R side which drains into the IVC directly) and the L renal vein can be compressed btwn the aorta and the SMA. This can lead to pressure build up and varicocele on the L side.
107
Does varicocele or hydrocele transilluminate light (meaning you can shine light through it)?
Hydrocele does. Varicocele does NOT.
108
In addition to being associated w/ insulin resistance, what else may acanthosis nigricans signal?
Malignancy of the GI tract or the lungs.
109
What are the findings in Peutz-Jeghers syndrome?
Pigmented mucocutaneous macules and hamartomatous polyps in the GI tract.
110
What is the mechanism of action of leuprolide?
It is a GnRH agonist. By being present at tonic levels it suppresses the axis.
111
Flutamide acts as...?
A competitive testosterone receptor inhibitor
112
Where do primordial germ cells originate and where do they migrate to?
Originate in the yolk sac. Migrate to the gonadal ridge.
113
What sort of cardiac abnormalities are most common in DiGeorge syndrome?
Conotruncal abnormalities like persistent truncus arteriosus, tetralogy of Fallot and interrupted aortic arch.
114
What causes hyper IgM syndrome? Why?
Absence of the CD40 ligand causes it because T cells (once activated) use their CD40 ligand to bind to CD40 receptors on B cells and this signals class switching from IgM to another class.
115
In what manner is CD40 ligand deficiency inherited?
X-linked recessive.
116
What are the key features of Gaucher disease and what enzyme is deficient?
Key features: hepatosplenomegaly, pancytopenia, bone pain/osteopenia
Lack of B-glucocerebrosidase
117
What are the key features of Fabry disease and what enzyme is deficient?
Angiokeratomas, peripheral neuropathy and glomerulopathy.
Alpha-galactosidase deficiency.
118
What enzyme is deficient in Krabbe disease?
Galactocerebrosidase. Presents w/ progressive neurodegeneration, peripheral neuropathy and optic atrophy
119
What enzyme is deficient in Niemann-Pick disease?
Sphingomyelinase. Presents w/ macular cherry-red spot, progressive neurodegeneration and hepatosplenomegaly.
120
Name two anti-TNA-a agents
infliximab and etanercept
121
What is meant by transduction in terms of bacterial DNA acquisition?
It means bacteriophage-mediated transfer of genetic info.
122
Which glomerular disease is often seen in association w/ HIV, heroin addiction and sickle cell disease?
Focal segmental glomerulosclerosis.
123
Describe hand-foot-genital syndrome. What sort of gene is mutated in this disorder?
In this there are malformations of the distal limbs like hypoplastic fist digits, and there are mullerian fusion abnormalities (which can lead to miscarriages). This is the result of a mutation to a homeobox gene (HOXA13).
124
What is meant by afterload in skeletal muscle? How about preload?
The force against which the muscle fiber must contract.
Preload = the initial muscle fiber length prior to contraction. Increasing preload increases contractile velocity up to a maximum value.
125
What is the relationship between afterload and contraction velocity in skeletal muscle?
They are inversely proportional.
126
What happens during the cooling stage of PCR? How about when the temp is raised to like 72C (still below the melting/denaturing temp)?
Cooling --> primers bind to single stranded DNA
Heated to 72C --> Primer extension by Taq DNA polymerase.
127
Why can middle cerebral artery infarct cause homonymous hemianopsia?
B/c this artery supplies the lower optic radiations w/in the temporal lobe (Meyer's loop) and the upper optic radiations in the parietal lobe.
