3/4 UWORLD test # 32 Flashcards Preview

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Flashcards in 3/4 UWORLD test # 32 Deck (33):
1

Q 1. Eyelid heaviness with mediastinal mass. What is going on? embryological origin of this mass?

thymoma (or thymus hyperplasia) in Myasthenia gravis
3rd pharyngeal pouch (endoderm)

2

Q 1. Origins for
- pharyngeal clefts
- pharyngeal arches
- pharyngeal pouches

CAP
- Cleft: ectoderm
- Arch: mesoderm, neural crest
- Pouch: endoderm

3

Q 1. Pharyngeal pouches: each structure gives rise to what?
- 1st pouch
- 2nd pouch
- 3rd pouch
- 4th pouch

- 1st: middle ear cavity, mastoid air cells, auditory tube (eustachian tube)

- 2nd: tonsil

- 3rd: thymus (ventral), inferior parathyroid (dorsal)

- 4th: ultimobranchial body (ventral) superior parathyroid (dorsal)

4

Q 2. Blotchy red muscle fibers on Gomori trichrome stain: what does this suggest? what are clinical findings (4)?

RED= oxygenated organelle = mitochondria

biotchy red muscle fibers suggest accumulation of enlarged/abnormal mitochondria on muscle fiber
-> mitochondrial myopathy

- myoclonic epilepsy, Leber optic neuropathy (blindness), stroke like episodes- encephalopathy, lactic acidosis

5

Q 4. what is tx regimen for prevention of recurrence of HSV2 infection? how long? which med is preferred? why?

- daily oral intake for years: medication will not reach to latent infection, but it can still suppress recurrent infection

- valacyclovir is preferred due to good bioavailability

6

Q 5. Ether and other organic solvents inactivate what structure of virus?

viral envelope

7

Q 6. How do corticosteroids affect neutrophil level? mechanism?

neutropilia

corticosteroids impair margination of neutrophil -> lack of neutrophil delivery to site of inflammation -> accumulation of neutrophil

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Q 7. What is Argyll Robertson pupil in tertiary syphilis?

normal accomodation, but lack of pupillary light reflex

9

Q 8. In fructose kinase deficiency, what enzyme metabolizes fructose (thus fructose kinase deficiency is asymptomatic)?

hexokinase

10

Q 9. If incapacitated patient does not have advanced directive, who can act as surrogate decision maker? who will be the second if this first decision maker does not exist?

family member
in the absence of family member, person who cares/know patient can be a decision maker

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Q 11. HIPAA: under what situation can physician provides patient's health information in request to family member

only if patient provided verbal or written authorization

12

Q 12. neuroscience: what is length constant ( or space constant)? How is myelin associated with it?

how far LENGTH (thus called as length constant) along an axon an electrical impulse propagate.

Myeline works as insulator. It prevents dissipation of electrical impulse as electrical impulse propagate along an axon. Thus demyelination diseases will reduce length constant

13

Q 12. Definition: temporal summation vs. spatial summation

- temporal summation: additive effect of postsynaptic membrane potential (NOT ACTION POTENTIAL- which has the same magnitude all the time as it is generated once membrane potential reaches threshold) after multiple stimulation from SAME neuron (at different timing, thus temporal)

- spatial summation: additive effect of postsynaptic membrane potential after multiple stimulations from OTHER multiple neurons.

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Q 12. neuroscience: what is time constant? How is demyelination disease associated with it?

TIME it takes for a change in MEMBRANE POTENTIAL to achieve 63% of new value. (membrane potential decreases as impulse propagates) The less time constant is, the quicker it changes membrane potential (thus faster conduction speed)

Demyelination disease will lower conduction speed, thus increases time constant

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Q 15. Subclavian steal syndrome
- How does blood flow look like
- etiologies (3)
- Diagnosis
- symptoms (2)

- occlusion of subclavian artery-> lack of blood flow to vertebral artery in affected side-> retrograde flow of blood from contralateral vertebral artery to vertebral artery in affected side

- two possible etiologies
1. artherosclerosis
2. Takayasu arthritis (rare)
3. prior heart surgery (eg. coarctation repair)

- Doppler ultrasound for blood circulation used as diagnostic tool

- symptoms
1. upper extremity ischemia
2. headache/vertigo: limited flow to vertebral artery-> vertebrobasilar insufficiency

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Q 16. What CD antigen is missing in leukocyte adhesion deficiency (LAD)? What is gross appearance of infection site in LAD?

- CD18 (LFA-1, integrin)

- lack of purulence: no pus (pus is dead neutrophil)

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Q 17. Gastrectomy with positive Romberg test, loss of bilateral vibration sensation, bilateral motor deficits.
what is going on?

Subacute combined degeneration
B12 deficiency
: B12 is absorbed in terminal ileum. Absorption requires intrinsic factor (IF), which is synthesized in stomach

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Q 19. What classes of antiarrhythmic drugs (2) cause QT prolongation/ Torsades? Which drug has the lowest incidence of Torsades?

1. class IA
2. class III

- amiodarone has the lowest incidence of Torsades

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Q 19. Adenosine
- mechanism of action
- indication
- adverse effects

- opens K+ channel -> induce hyperpolarization

- rapid termination of SVT

- hypotension, flushing, syncope: adenosine is potent vasodilator

20

Mg2+ is indicated for what two cardiac conditions

- to reverse Torsades
- to reduce digoxin toxicity

21

Q 21. omalizumab
- mechanism of action
- indications (2)

- Anti-IgE antibody

1. moderate to severe asthma
2. insensitivity to inhaled glucorcorticoids

22

Q 22. Where does Legionella colonizes?

water habitat

nosocomial pneumonia by legionella is highly likely due to contaminated water system in hospital

23

Q 24. Is sickle cell trait (not disease) associated with renal papillary necrosis?

oh yes. so does in sickle cell disease.

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Q 24. Renal papillary necrosis
- four etiologies, what is common pathophysiology for all these etiologies?
- microscopic appearance
- symptoms (3)

SAAD papa
S- sickle cell disease or TRAIT as well
A- Anlagestics (NSAIDs)
A- Acute pyelonephritis
D- Diabetes
All of these etiologies lead to renal hypoperfusion
-> coagulative necrosis at renal papillae in microscope

- symptoms: hematruia, proteinuria, flankpain

25

Q 25. How pulmonary edema affects lung compliance?

pulmonary edema: accumulation of transduate liquid into lung interstitium/ alveoli (from pulmonary vessels)

-> increased surface tension surrounding alveoli

-> decreased compliance (alveoli becomes less stretchy, rather becomes sticky. So it is hard to expand alveoli)

26

Q 26. hyperpigmented bump around breast, the bump becomes tender/swelling during mens, lactation, pregnancy. What is most likely going on? pathophysiology?

accessory nipples

due to failure of involution of mammary ridge

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Q 27. necrotizing enterocolitis
- affected population
- pathophysiology
- complications (3)

- pretermed new born

- immature immune system -> bacteria in food cause excess inflammation in intestinal wall -> ischemic necrosis

complicated by
1. death: due to intestinal perforation
2. pneumatosis intestinalis: air in the abdomen
3. obstruction: due to fibrosis

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Q 29. Glaucoma drugs: beta blocker (timolol) vs. cholinomimetics (pilocarpine)

- mechanism of action
- site of action

beta blocker (timolol)
- decrease aqueous humor synthesis
- ciliary EPITHELIUM (site for aqueous humor synthesis)

Cholinomimetics (pilocarpine)
- increase aqueous outflow
- ciliary muscle (ciliary muscle contraction leads to opening of trabecular meshwork)

29

alpha agonist (epinephrine) is indicated to what type of glaucoma? why?

- open angle galucoma only

- should not be used for closed angle glaucoma because it can cause mydriasis -> further narrowing of angle

30

glaucoma drugs- examples for
- decrease aqueous humor synthesis
- increase aqueous humor outflow

- decreased aqueous humor synthesis
1. acetazolamide
2. alpha agonist (epinephrine)
3. beta blocker (timolol)

- increased aqueous humor outflow
1. cholinomimetics (pilocarpine, carbachol)
2. prostaglandin analogue (bimatoprost, itanoprost)

31

Q 32. Ranolazine
- mechanism of action
- effect on HR? contractility?
- indication
- side effects (4)

- inhibition of late phase sodium entry -> reduce cardiomyocyte wall tension/ oxygen consumption

- no effect on HR or contractility

- angina refractory to other medications

- constipation, headache, nausea, QT prolongation (but NOT torsades)

32

Q 33. How does Corynebacterium diphtheriae acquires virulence?

It acquires pathogenecity by bacteriophage mediated infection.

Corynephage beta (bacteriophage) infects Corynebacterium diphtheriae
-> bacteriophage gene (Tox gene) is incorporated into diptheriae genome
-> synthesis of exotoxin

33

Q 37. Describe pathophysiology of alcohol-induced chronic pancreatitis

alcohol induced secretion of protein rich fluid
-> plug formation in pancreatic duct
-> calcification & pancreatic insufficiency