UWorld Test 5/13/2014 Flashcards
What neurotransmitter mediates opioid tolerance? What drug can be used to decrease opioid tolerance
Opioid tolerance seems to involve phosphoyrlation of opioid receptors and increased NP. Glutamate seems to increase opiod tolerance by increasing phosphyrlation of opiod receptors, increasing adenylyl cyclase activity and increasing NO levels. Use Ketamine, a glutamate receptor blocker, to decrease opiod tolerance
What binds to the 3 different opioid rectpors
Mu= morphine, delta = enkephalin, kappa = dynorphin
Beta-endorphin is an endogenous peptide that is derived from what? What other hormone is it therefore structurally similar to?
Beta-endorphine derived from proopiomelanocortin (POMC). POMC is a polypeptide precursor that is cleaved to form beta-endorphine, ACTH and MSH. This suggests there is a close physiologic relationship between the stress axis and opiod system.
Age related macular degeneration causes what kind of vision loss
Central scotoma
Bilateral schwannomas are a/w
NF-type two
Opioids inhibit the release of what?
Serotonin, Substance P, Ach, NE, Glutamate
What is the relationship between the permeability of a membrane to an ion and the equilibrium potential of that ion?
When membrane potential is close/same as the equilibrium potential of an ion, it becomes permeable to that ion. The more permeable a membrane is to an ion, the more that ion’s equilibirum potential contributes to the membrane potential.
What japanese delicacy can cause paresthesias, loss of reflexes?
Tetrodotoxin from puffer fish. Binds to Na+ channels and prevents depolarization
Vitamine E deficiency causes demyelination of what?
Posterior columns and spinocerebellar tract - presents with ataxia, parasthesia, impaired position and vibration sense
Vitamine E deficiency can mimic what?
Friedrich Ataxia
What is length constant and how is it related to myelination
Length constant is the length a nerve impulse can propagate. A low length constant reduces the distance it can travel. Myelination increaeses the length constant and decreases the time constant, therby improving axonal conduction speed. Demyelination impairs stimulus transmission
What viral inflection has a predilection for the temporal lobes? What kind of sx are seen? What is found on macroscopy?
HSV-1 virus. Sx: specific - aphasia, olfactory hallucinations (olfactory bulb involvement), personality changes (amgydala invovlemnt). Macroscopic: Edema/ hemorrhagic necrosis.
What is a common cause of recurrent lobar hemorrhage?
Cerebral amyloid angiopathy. Occurs when beta amyloid is deposited into vessel wall =>weakens, prone to rupture. Not a/w with systemic amyloidosis. Recurrent hemorrhage stroke common. Often occurs in cerebral hemisphers (therefore “lobar” hemorrhage” lower mortality and more benign compared to hypertensive strokes.
What is the triad of Meniere’s disease. What is the pathogenesis
Triad of sensorineural hearing loss, tinnitus and vertigo. Increased endolymph from defective resoprtion of endolymph. Causes vestibular and cochlear damage to inner ear.
What is the rinne test? What are the findings in conductive and sensorineural hearing loss?
Rinne test. Put tuning fork near to external auditory meatus count how long patient can hear it for and how loud. And then do same on mastoid bone. Normal is that air conduction is louder and longer than bone. If CONDUCTIVE LOSS = bone will be louder than air (this is abnormal finding). if SENSORINEURAL FINDING = air > bone (normal finding)
