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NBME 13 discussion

Discussion in 'Step I' started by ijn, 03.09.12.

  1. ijn

    ijn

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    Yeah. If they have oral herpes, the answer would be trigeminal ganglion. If they have genital herpes, then it's the the sacral level DRGs. VZV is also a human herpes virus and acts in a very similar manner in that it lies dormant in dorsal root ganglion.

    The question is essentially asking what downstream effects are prevented. The receptor component is not mutated so the ligand will interact with the receptor. Only the kinase part is mutated. The direct downstream effect of a failure to autophosphorylate is a failure of phosphorylation of downstream molecules via whatever kinase cascade is attached to this receptor.

    The question is asking what is most likely to have caused his gastric cancer, not his ulcer. Naproxen can cause some bladder cancers but not gastric cancer. Diet apparently is the correct answer but honestly I think it's a ****ed up question because the #1 reason is H. pylori. Smoking elevates your risk by 50%. I have not seen a single source that quantifies the risk of a high nitrosamine diet but I'm sure there's some pubmed article out there that can justify it.
  2. Morsetlis

    Morsetlis SGU MS-4

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    Lipolysis is b3.

    It is helpful to know that thromboplastin (the T in APTT) = phospholipids + TF
  3. JasonE

    JasonE

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    beta3. blow me. they shouldnt put that as a choice
  4. Morsetlis

    Morsetlis SGU MS-4

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    They knew you wouldn't remember it ;)
  5. JasonE

    JasonE

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    no one talks about beta3. many resources have lipolysis listed under beta2
  6. Morsetlis

    Morsetlis SGU MS-4

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    b2 for uterus relaxation is 100% sure.

    I learned lipolysis as b3. The Guyton textbook lists it as b1. Either way it's not b2.

    [​IMG]
  7. Morsetlis

    Morsetlis SGU MS-4

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    http://www.ncbi.nlm.nih.gov/pubmed/11300357

    "In vitro lipolysis stimulated by low (-)-isoprenaline concentrations (< or =30 nM) in epididymal white adipocytes from Sprague-Dawley rats was inhibited at least 60-80% by the specific beta1-antagonists LK 204-545 and CGP 20712A (1 microM), suggesting that at these low (10 nM) concentrations of (-)-isoprenaline lipolysis was primarily (80%) but not solely mediated via beta1-adrenergic receptors. Low concentrations (100 nM) of (-)-noradrenaline and formoterol also confirmed a role for beta1-adrenergic receptors in mediating lipolysis at low concentrations of these agonists. At higher agonist concentrations, beta3-adrenergic receptors were fully activated and were the dominant beta-adrenergic receptor subtype mediating the maximum lipolytic response, and the maximum response was not affected by the beta1-antagonists, demonstrating that the beta3-receptor is capable of inducing maximum lipolysis on its own. Studies of lipolysis induced by the relatively beta2-selective agonist formoterol in the presence of beta1-blockade (1 microM CGP 20712A) demonstrated the inability of the beta2-selective antagonist ICI 118-551 to inhibit the residual lipolysis at concentrations of ICI 118-551 < or = 1 microM."
  8. JasonE

    JasonE

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    not doubting you. i just dont think they should put something iffy as an option. lionel raymon from the kaplan videos goes out of his to say lipolysis is beta2.

    and no one talks about beta3. they only talk about beta1,2. beta3 will never be tested on step1
  9. awesomedude

    awesomedude

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    block2-Que23 A 28 year old woman comes to the physician for a health maintance examination, she tearfully tells the physician that she and her new husband are having problems, she says that she wants to going out with friends but he does not enjoy being with people and prefer individual activity like hiking she says he seems indifferent to sexual intimacy and neither shows much emotions nor understands her feelings at all. which of the following personality styles best explaines the husband's behaviour?
    A] Avoidant (wrong)
    B] Narcissistic
    C]Paranoid
    D] Schizoid
    E] Schizotypal(may be right?????)

    block3-Que45 A 35 year old man comes to the physician because of chronic cough for 5 months he says "I worry i may have lung cancer like my dad" he has smoked 2 packs of cigarettes daily for 15 years. physical examination & x-ray of the chest shows no abnormalities which of following responses is most appropriate to encourage this patient to quiet smoking?
    A] have you ever considered changing to chewing tobbaco?
    B]have you ever thought about quitting smoking?
    C] i'd like to refer you to a hypnotist to help you quit smoking
    D]i'll prescibe some nicotine pathces for you. that will help you cut down on your smoking
    E] try to low nicotine cigarettes for a while that will decreses your chances of getting lung cancer
    F] you must stop smoking immediately or you will most likely get lung cancer someday like your father (wrong) :(

    block 4-Que21 A 16 year old boy has a 6 month history of type 1 DM & requires daily insulin injections his blood glucose control has been poor recently which the physician suspects may be related to the patients reluctance to self administer insulin which of the following questions is most appropriate to broach this issue with the patient?
    A] giving yourself insulin injection can be difficult whats it like for you?
    B] I get the feeling you have not taking your insulin regularly.whould you like me to arrange some training for you by our nurses?
    C] its been my experience that most poorly controlled diabetics have trouble giving themselves insulin. do you have this problem? (wrong)....:(
    D]you are clearly having difficulty with insulin injections. whould you like to arrange for a family member to give you your shots?
    E] you seem to have missed your shots how often has this happened?

    block 3 Que 13 A 60 year old man comes to the physician because of 2 year history of progressive shortness of breath with exertion his two younger siblings have similar symptoms his mother died of dilated cardiomyopathy . physical examination shows jugular venous distention and ankle edema there is hepatomegaly. inspiratory crackles are heard over both bases. a chest x-ray shows cardiomegaly and pulmonary conjestion angiography confirms dilated cardiomyopathy. an artial endocardial biopsy specimen shows abnormal sarcomeres with paracrystalline inclusion in mitocondria. sequencing of mitochondrial DNA shows G-to-A transition. this results in an added A:T base pair to the 3' end of tRNA thus shortening the C loop which of the following is the most likely effect of this mutation on mitochondrial function?
    A] decreased mRNA stability (wrong)
    B] decreased protein synthesis
    C] decreased replication
    D] increased mRNA stability
    E] increased protein synthesis
    F] increased replication

    please provide answer with explanation......
    thanks in advance.....:)
  10. drmsms

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    1.Schizoid bcz he doesn't enjoy being with others i.e voluntary social withdrawl,he has limited emotional expression.it is not Schizotypical bcz there is no odd thinking
    2.''have u ever thought of quitting" i.e ask pt how he feels abt his smoking
    3.''giv'n insulin yourself is difficult.howz is it for u?"i.e open ended question
    4.dec protein synthesis. i understood it as there is some thing wrong with t-RNA.so it should dec protein synth.
    Hope it helps.any corrections are welcome:)
  11. ijn

    ijn

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    The answer is D. Schizoid. When you see a question about schizoid think of them as happy loners (i.e. the hiking).

    Being paternalistic right off the bat is never the right answer. You should use open ended questions to see what stage of change the patient is in. The answer is "B) have you ever thought about quitting smoking?" and then going from there.

    Don't insult the patient by saying they're poorly controlled. Always think "what would a fuzzy sappy jesus bear do?" Fuzzy sappy jesus bear would ask about the boy's feelings and empathize with the patient. The answer is "A. Giving yourself insulin injections can be difficult; what's it like for you?"

    Decreased protein synthesis. You're screwing up the 3' CCA sequence on the tRNA so you're not able to properly charge tRNA with amino acids. mRNA stability is normal, but translation is decreased.
  12. Morsetlis

    Morsetlis SGU MS-4

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    A] decreased mRNA stability - this choice only refers to mRNA, which isn't affected
    B] decreased protein synthesis - tRNA and mRNA are involved in protein synthesis. Mutated tRNA -> less synthesis
    C] decreased replication - this choice only refers to DNA
    D] increased mRNA stability - this choice only refers to mRNA
    E] increased protein synthesis - opposite of B
    F] increased replication - this choice only refers to DNA
  13. WJC biochem

    WJC biochem

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    Can you all double check these answers for some reason I can't check if mine are right or wrong? (free test from school without extended assessment)

    44. A 55 yo man comes to physician b/c of a 3-day hx of fever and chills. He has ESRD tx with hemodialysis. His temp is 102.6 F, pulse 110/min, and BP 156/92. PE shows a tunneled CVC entering the chest below the clavicle; the area surrounding is not tender. Echo shows a 3-cm vegetation on his tricuspid. Which organism is most likely cause?

    A E. Coli
    B Klebsiella Pneumo
    C Staph Aureus (right?)
    D Group A strep
    E Viridans

    Pretty sure C is right, just wanted to make sure

    49. A 42 yo man has an autoimmune disorder with proximal muscle weakness in lower extremity. Arrows in this electron micrograph shown indicate membranes that contain high concentrations of channels targeted by this condition. Whats the dx?

    A. MS
    B. MG (This is right?)
    C Lambert Eaton
    D Periodic paralysis
    E Tetany

    I put B looked kinda like a NMJ to me, but not sure.
    Last edited: 05.09.12
  14. Morsetlis

    Morsetlis SGU MS-4

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    Viridans would come from the mouth. Since it looks like the infection came from skin I'd say S. aureus as well. And from wikipedia (lol): In contrast, Staphylococcus blood stream infections are frequently acquired in a health care setting where they can enter the blood stream through procedures that cause break in the integrity of skin like surgery, catheterisation or during access of long term indwelling catheters or secondary to intravenous injection of recreational drugs.

    Well, it depends whether the membrane is presyn or postsyn. Since the highest concentration of postsyn channels (NmAChR) is on the endplate it would be MG. MS is CNS, and LES targets presyn Ca++ channels. Tetany involves retrograde axonal transport of the bacterium.
  15. ijn

    ijn

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    Yeah, S. aureus is correct. Right sided vegetation is almost always going to be that or candida.

    The answer to the second one was Lambert Eaton. They were pointing at the presynaptic cell. You had to recognize the secretory granules to really be sure of which cell you were looking at. Also in general, myasthenia is going to present with cranial nerve weakness, while Lambert is going to have limb-girdle weakness. And if you want to play odds on sex (which the USMLE generally does follow), then Lambert is going to be in men (from smoking) and myasthenia in women.
    Last edited: 05.09.12
  16. Morsetlis

    Morsetlis SGU MS-4

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    No picture man!
  17. figo

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    1. Atypical cell with abundant lacy cytoplasm is derived from? ... I thought this was plasma cell derived from B Cell. I picked that on the NBME 13 but got wrong, so is the ans for this one plasma cell.
  18. ijn

    ijn

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    If that's the person with mononucleosis, then the answer is a CD8 T-cell.
  19. figo

    figo

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    thanks..that is the Q, i guess i overlooked the Q
  20. WJC biochem

    WJC biochem

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    I really have no idea on EM pictures of the NMJ, anybody have a link where I can see secretory granules and the like?

    Is there a way I can post the picture from the test so someone can point out the granules?
    Last edited: 05.12.12
  21. ijn

    ijn

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    [​IMG]

    So M is the postsynaptic muscle. T is the presynaptic cell. You can see vesicles on the superior part of the micrograph. They're not going to be super prominent but they're fairly distinct.

    [​IMG]
    Here's a better example. The vesicle-less side is the muscle, the vesicle side is the terminal bouton of a presynaptic neuron.

    So if they pointed at the side with vesicles, the disease would be Lambert-Eaton. If they pointed at the side without vesicles, then it's myasthenic gravis. A few other permutations of this questions could just be neurophys, where they could just ask what type of receptor is found at each membrane.
  22. WJC biochem

    WJC biochem

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    Attached is the picture showing the presynaptic neuron 9see my post above), if someone could tell me where in the photo I can identify the neurosecretory granules or just make more sense out of it, it would be appreciated. (EDIT: i was posting this before the above was up, so thank you!)

    Another one I would like to verfiy from section 2:

    16. A 5-month old boy is brought to the physician because of a 5-day hx of difficulty feeding. PE shows macroglossia and enlargement of the anterior neck at the midline. A CT shows a 4-cm, well-defined, cystic structure in the neck. A remnent of which of the following is the most likely cause?

    A. Cervical Sinus
    B. First Pharyngeal puch
    C. Fourth Pharyngeal pouch
    D. Occipital myotome
    E. Thyroglossal Duct (right? this sounded like a thyroglossal duct cyst to me)

    Attached Files:

  23. WJC biochem

    WJC biochem

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    From looking at your photos, ijn (which by the way your help was much appreciated, thanks), I think the picture in the question may not have been of the NMJ, but rather just the neuron itself. I don't know the picture from the test looks unlike any other I have seen.
  24. ijn

    ijn

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    I think in the bottom you see a kind of stippled, organized pattern of what I presume to be myofibrils that each contain hundreds of sarcomeres. At the top near the arrows you see the secretory vesicles. In between the two you see junctional folds of an NMJ. To the left you see the nucleus of the muscle cell.
  25. WJC biochem

    WJC biochem

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    OHHHHH, I finally have come to the realization of what the arrows are pointing to, that is the nerve membrane not the muscle membrane. Yeah I thought this was NMJ when I first looked at it cause there are myofibrils but I was totally confused by the involutions of the muscle membranes. Finally this picture makes sense to me, thank you!
  26. mdeast

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    Was E not the right answer? That seems like a tricky question. I don't think it's A or B. They wouldn't really present in the mid-line. Cervical sinus (lateral neck), First (near ear/mandible). Fourth (super rare), but I guess could present in the mid-line. I had to look up D but it seems to be the origin of the muscles of the tongue. I would have guessed E too. I think C is possible. But, so much more unlikely.
    Last edited: 05.12.12
  27. WJC biochem

    WJC biochem

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    Thanks, I don't have the ability to check if its right or wrong, as the NMBE self assessment I took was without the extra feedback since my school gives us one freebie. Since, we both agree, I hope its safe to assume E is right. Only thing that seemed off about this was the macroglossia, wasn't sure what they were trying to get at with that since it cant be an undescended thyroid if there is a thyroglosaal duct cyst, right?
  28. jatt12

    jatt12

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    E is correct choice
  29. Morsetlis

    Morsetlis SGU MS-4

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    The pouches are on the inside, and they give rise to the thymic / parathyroid structures, along with the hyoid bone. They are not really known to create a cyst. Cervical/branchial sinus is usually on the side, and can create a sinus, cyst, or fistula (2nd to 4th clefts). If it's in the center, then it is most likely the thyroglossal duct cyst (which should obliterate).
  30. Morsetlis

    Morsetlis SGU MS-4

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    Don't forget about Myotonia Congenita (Cl- channel defect) in the postsynaptic muscle ;)
  31. WJC biochem

    WJC biochem

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    I don't have room in my brain for that kind of knowledge... I looked but I don't think anyone actually verified the answer to the loading dose question (section 3, Q2)

    His BW was 55 kg, the Vd=0.35 L/kg, Cp (target conc) was 8 mg/L and F=1 (IV). When i did my calc for Loading dose I got 154 mg, it had the following answers

    A)25
    B)50
    C) 100
    D) 150 (what i put is this right?)
    E) 200
  32. ijn

    ijn

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    Vd = Body weight / density
    Loading dose = Vd*Cp
    55 kg * 0.35 L / kg * 8 mg/L = 154 mg


    Yup. That's right.
  33. WJC biochem

    WJC biochem

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    Section 3 Q 35: A healthy 21-yo man dies suddenly of cardiac arrest after snorting cocaine. Cocain-induced inhibition of which of the following is the most likely explanation for the cardiac arrest?

    A) Acetylcholinesterase
    B) alpha-2 receptors
    C) Beta-2-receptors
    D) MAO
    E) muscarinic receptors
    F) NE reuptake (I put this and think its right)

    Can someone confirm that F is correct? also, I wonder what I would have done if they also put inactivated sodium channels since i know blockage of sodium channels can also be a cause for arrhythmia (ie. quinidine and TCAs)

    Another Q Section 3 number 36:

    A 21 yo AA man with sickle cell is brought to ED 2 hrs after pain crisis began. (blah, blah, blah)... he asks the physician for extra pain meds to "kill me because I can't take it anymore." Which of the following initial actions by the physician regarding the patient's request is most appropriate?

    A) contact the hospital ethic committee
    B) restrain the patient
    C) reevaluate the patient after his pain has been controlled (is this right?)
    D) administer general anesthesia for sedation
    E) comply with patient's request

    This one really threw me for a loop, I expected to find an answer that said: admi/hospitalizet the patient, and dont let him leave. Since I thought restraining or sedation may be extreme (the patient isn't actively throwing a tantrum or grabbing things to try and kill himself), I pu C. I feel like C may be right because the patient's cognition is not intact due to extreme pain, so his threat should not be taken seriously until you have restored his normal cognition (stopped the pain).

    Section 3 Q 49:
    A 49 yo man with pancreatic CA undergoes a whipple. During the procedure the cut end of stomach is joined to the jejunum. Which of the following nerve structures can be cut to decrease stomach acid output and decrease the likelihood of ulcers forming in the jejunum at the site of junction with the stomach?

    A) celiac plexus (i think I put this but now i think I was wrong, cause i talked myself out of F)
    B) iliohypogastric nerves
    C) Phrenic nerves
    D0 subcostal nerves
    E) sympathetic chain
    F) vagal trunks (I think this would be right as I believe the celiac plexus is actually sympathetic not parasymp, and vagotomy was the old school tx for PUD)

    I you can help with these it would be appreciated, I am unable to check answers, but did save all the Qs

    Can someone help me with these?
    Last edited: 05.13.12
  34. jatt12

    jatt12

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    35: F
    36:c
    49:f
  35. Morsetlis

    Morsetlis SGU MS-4

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    Agree with both F's.

    Dunno about psych, but you always want to control pain first.
  36. jatt12

    jatt12

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    Yes, you are correct, after patient pain is relieved you would re evaluate him/her.
  37. figo

    figo

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    1. 42 yr woman comes to the physician because of 3 weeks history of numbness of the fingers on the left hand. Neuro exam shows loss of touch graphesthesia and loss of two-point discrimination in the left hand. Lesion location is?? Its picture q. I thought the lesion will be on temporal right hence pick ans (C) it come back wrong any one care to explain. Thanks

    2. Man recovering from stroke he is at increase risk for what: agoraphobia, MDD, obsessive compulsive disorder, PTSD and social phobia


    3. 32 yrs old woman who has history of progressive shortness of breath and anxiety. Symptoms become much more pronounced as the day progresses. BMI is 24kg/m pt has difficulty taking long deep breath. pH 7.33, Pco2 70 and Po2 65. Decrease vital capacity, tidal volume and ERV. Residual volume within normal reference what is the underlying cause: Alpha 1 antitrypsin deficiency, central nervous system neoplasia, chronic bronchitis, chronic opiate use, myasthenia gravis and obesity&#8230;. is this myasthenia gravis if so can someone explain the pathophsyio.

    4. An experimental model of treatment for sickle cell disease involves reactivating the genes that code for the beta chain of fetal hemoglobin. This treatment is most likely increasing the affinity of hemoglobin for which of the following. 2,3 BPG, Co2, Cl-, O2 and protons


    thanks guys.
  38. ijn

    ijn

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    1. B (postcentral gyrus / somatosensory cortex)
    2. depression
    3. myasthesia gravis => deplete ACh as the day progresses => diaphragm becomes paralyzed => hypoventilation (hypoxemia, hypercapnia) and respiratory acidosis
    4. HbF has increased affinity for O2 (which would be beneficial, because sickling is induced by hypoxia)
  39. johndoe3344

    johndoe3344

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    Why would HbF have beta chains?
    Last edited: 05.14.12
  40. Morsetlis

    Morsetlis SGU MS-4

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    The chain formerly known as beta. Drugs used could be decitabine (global demethylator) or hydroxyurea.

    Well, I'd assume the answer is O2.
  41. Joe Damagio

    Joe Damagio

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    Block 3/ #31 An epidemiologist is investigating an outbreak of diarrhea among a total of 1000 consumers of vegetables. Of those consumers, 800 people ale tomaloes and 200 people ate lettuce. A total of 400 people became ill; 80 of these people ate tomatoes, and 40 people ale lettuce. Which of the following indicates the probability of diarrhea having developed in people who consumed lettuce?
    A)0.08
    B)0.1
    C)0.2
    D)0.4
    E) 0.5
    Can anyone explain this one step by step?
    Thanks
  42. Joe Damagio

    Joe Damagio

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    A 63-year-old woman comes to the physician because of a 2-month history of a drooping left eyelid, intermittent pain of her left eye, and an unusually large pupil. Her husband has told her
    that the eye appears to be "looking sideways." Ophthalmologic examination shows ptosis, lateral strabismus, and mydriasis of the left eye. An MRI of the brain shows an aneurysm of the left
    poslerior communicating artery. The function of which of the following muscles is most likely to remain intact in this patient?
    A) Ciliary
    B) Inferior oblique
    C) Inferior rectus
    D) Pupillary constrictor
    E) Superior oblique
    F) Superior rectus
    Never like the eye stuff. Please help me out.
    Thanks.
  43. Morsetlis

    Morsetlis SGU MS-4

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    SDN 2+ Year Member
    Drooping eyelid is malfunction of either levator palpebrae superioris (motor of CN3) or tarsalis (sympathetic from superior cervical ganglion).

    Looking sideways is a "down and out" phenomenon from losing motor of CN3, letting CN6 and CN4 predominate.

    Large pupils is a loss of parasympathetic from CN3.

    Therefore, CN4 and CN6 muscles are still present: superior oblique and lateral rectus.
  44. Morsetlis

    Morsetlis SGU MS-4

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    200 people ate lettuce.

    40 people were sick, who ate lettuce.

    40 / 200 = 0.2
  45. Joe Damagio

    Joe Damagio

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    Thanks! Doc.
    Much appreciated
    Joe
  46. Hopeful Dr

    Hopeful Dr

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    During an experiment, a cuff occluder is placed on the left renal artery of a normal rat and inflated to cause a 90% decrease in the cross-sectional area of the artery. A catheter is placed in the left and right renal veins to sample the effluent. The concentration of which of the following substances will most likely be higher in the effluent from the left renal vein than that from the right renal vein?
    A. ADH
    B. Aldosterone (wrong)
    C. Endothelin
    D. Epinephrine
    E. Renin

    What is the right answer? And, can you please explain! Thanks!
  47. sarcastical

    sarcastical

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    E. Renin - this scenario is like renal artery stenosis, where decreased perfusion of the afferent arteriole will simulate decreased BP, causing a release of renin from JG cells.
  48. Hopeful Dr

    Hopeful Dr

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    Yeah I see that now. I was thinking more of RAAS activation leading to inc. Aldosterone from the adrenals, and therefore because of the left adrenal v. dumping directly into left renal v. the concentration of Aldo is higher...I guess I didn't think like NBME
  49. metallica81788

    metallica81788 Keeper of the Llamaworm Moderator Emeritus

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    Checked the thread, I don't think these were posted - if so, sorry. Thanks for the help.

    4-36: A 25 year old woman undergoes radical mastectomy with removal of axillary lymph nodes on left side. After the operation, she develops painful edema of the left upper extremity. Which of the following therapies is most likely to decrease swelling in this pt?
    a)application of heat
    b)compression sleeve
    c) diuretic therapy
    d)exercise therapy
    e)passive movement (wrong)

    1-21: A male newborn was delivered at 38 weeks gestation following an uncomplicated pregancy. 12 hours later, he begins sucking frantically and crying inconsolably. He overreacts to stimuli around him and has a marked startle response. Symptoms slowly resolve over the next 2-3 weeks. The most likely explanation for these symptoms is maternal use of which of the following substances during pregnancy?
    a)alcohol (I'm thinking it's this, but didn't pick it b/c I assumed w/ FAS it would be more intense)
    b)heroin
    c)LSD
    d)marijuana (wrong)
    e)psilocybin
  50. adele87

    adele87

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    4-36. B -- compression sleeve
    1-21. B -- heroin
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