A 24 year old male is evaluated for chronic headaches and visual changes. Intracranial calcified
mass is seen on MRI. Gross insp shows cystic spaces w thick brownish fluid rich in cholesterol.
The mass most likely shares a common origin w which:
A. Choroid plexus
B Pineal gland
C. Pituitary gland
D. Cerebellar vermis
E. Retina - correct answer Pituitary gland. Calcified cystic mass in a young adult w no other risks
is likely a Craniopharyngioma. Suprasellar region. Cystic or partially cystic w solid areas. LM
shows stratefied squamous epith and possibly Keratin pearls. Cysts are filled w yeloow viscous
fluid rich in cholesterol crystals.
Derived from Rathke's pouch remnants. Rathke's pouch is an evagination of the ectoderm that
lines the fetal oral cavity. It protrudes up to form the anterior pituitary gland. Posterior pit is
neuroectoderm.
___________ are calcified cystic tumors that derive from Rathke's pouch, whcih is an
embryonic precursor to the anterior pituitary. Commonly cause HA, growth failure, bitemporal
hemianopia. - correct answer Craniopharyngiomas
Kinesins move (toward/away) cell body while Dyneins move (Toward/away) cell body of
neuron. - correct answer Microtubular motor proteins. Kinesins move away from the cell body
toward the axon, carrying vesicles and organelles in anterograde transport. Dyneins move
toward cell body carrying things in retrograde transport. Dyneins also function in ciliary and
flagellar movement. Hydrolyze ATP to move.
What is Nissl substance? - correct answer The Rough ER of neuron which is in the cell body.
Does not extend to axons.
Which is larger microfilament, microtubule, intermediate filament? - correct answer
Microtubule. Then intermediate filament. Then microfilament.
_______ bias can occur with inappropriate (non random) methods or through selective attrition
of study participants. - correct answer Selection bias. It creates a population that does not
accurately represent the real population. Can result in erroneous conclusions.
The odds ratio approximates the _____ when disease prevalence is low. - correct answer
Relative risk.
,_______ can be defined as teh tiem between the initial detection of a disease and a specific
outcome or measured endpoint. - correct answer Lead time. Lead time bias occurs when
comparing two different tests for the same disease when one of the tests can accurately detect
the disease at an earlier stage
_____________ bias occurs when comparing two different tests for the same disease when one
of the tests can accurately detect the disease at an earlier stage - correct answer Lead time
bias. A study comparing disease survival times may erroneously conclude that using the earlier-
detection test prolongs survival, when in actuality, the increased survival is solely due to earlier
detection of disease.
_______________ bias occurs when someone misclassifies data secondary to individual
differences in interpretation or preconceived expectations regarding the study. - correct
answer Observer bias. It can be reduced w a double blind study and having multiple encoders
of data.
Are the nicotinic receptors on skeletal muscle endplate ligand gated or voltage gated and how
do they initiate signaling? - correct answer Ligand gated (ACh binds) and they open Na and K
channels.
Does the initial upstroke in the SA node depend on Na or Ca? - correct answer Calcium.
Everywhere else, skletal muscle, smooth muscle, cardiac muscle in purkinje fibers, it depends
on sodium.
Calcium does flood in when the depolarization from opening Na and K channels leads to VGCC
activation.
A 4 year old boy w difficulty walking. PMH shows frequent respiratory infections. Cultured cells
from the patient show a high rate of radiation induced genetic mutation. This patient is likely to
experience which of the following?
Neurofibrillary tangles in neocortex
Cerebellar atrophy
Loss of neurons in substantia nigra
Atrophy of caudate nucleus
Posterior column degeneration
Presence of Lewy bodies - correct answer Cerebellar atrophy in the first years of life is ataxia
telangectasia. These patients have recurrent sinopulmonary infections.
Ataxia telangiectasia patients have DNA hypersensitivity to ionizing radiation.
Higher risk of CA due to inefficient DNA repair.
, (Oculocutaneous telangiectasia is another manifestation, usually delayed.)
Neurofibrillary tangles in the neocortex is seen in alzheimers dz
Loss of neurons in SubNigra is parkinsons
Atrophy of caudate N is Huntingtons
Posterior column involvement is B12 and syphilis
Presence of Lewy bodies is PArkinsonism
I am a genetic disease characterized by sensitivity to ionizing radiation. Difficulty walking or
with intentional movements, repeated sinopulmonary infections, increased incidence of CA -
correct answer Ataxia telangiectasia
_________ virus infection is the MCC of aseptic meningitis - correct answer Enterovirus
infection. 90% of cases. ssRNA. Coxsackie, echoviruses, polioviruses. They all replicate in GI but
dont cause gastroenteritis.
Fever, malaise, aseptic meningitis in an unvaccinated immigrant child, followed by severe
myalgias and asymetric leg weakness, w hyporeflexia. - correct answer Polio. Damage to
anterior horn lower motor neuron cell bodies causes the hyporeflexia
3 Viruses spread by respiratory secretions capable of causing aseptic meningitis or encephalitis
- correct answer varicella
Mumps
Adenovirus
Sexually transmitted viruses that may cause aseptic meningitis - correct answer HIV, HSV 1 and
2, EBV and CMV. But HIV and HSV 2 are MCC
Transmission route of Togaviride? - correct answer Togaviridae such as Eastern, western and
Venezuelan equine encephalitis are transmitted by insect bites.
St. Louis encephalitis - family? - correct answer Flaviviridae. Arbovirus therefore most common
in summer and fall
California encephalitis - family? - correct answer Bunyaviridae. Arbovirus therefore Most
common in summer and fall
What are two viruses transmitted by blood transfusion that can cause aseptic meningitis? -
correct answer HIV, CMV
A physician is interviewing a teenage patient who is falling behind in school by abusing alcohol
and drugs. The physician's own daughter is abusing alcohol and drugs. The physician turns to
the parent and asks if the parent feels like slapping the child.