3/4 UWORLD test # 32 Flashcards
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)
Q 1. Origins for
- pharyngeal clefts
- pharyngeal arches
- pharyngeal pouches
CAP
- Cleft: ectoderm
- Arch: mesoderm, neural crest
- Pouch: endoderm
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)
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
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
Q 5. Ether and other organic solvents inactivate what structure of virus?
viral envelope
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
Q 7. What is Argyll Robertson pupil in tertiary syphilis?
normal accomodation, but lack of pupillary light reflex
Q 8. In fructose kinase deficiency, what enzyme metabolizes fructose (thus fructose kinase deficiency is asymptomatic)?
hexokinase
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
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
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
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.
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
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