uWorld 29 Flashcards
organ susceptibility to infarction after occlusion of a feeding artery is ranked from greatest to least how?
CNS, myocardium, kidney, spleen and LIVER (least likely)
why are infarcts in otherwise normal liver rare
DUAL BLOOD SUPPLY
what are microvilli made up of
actin
what is Nissle substance
RER in neurons
what is an examples of enhanced ability to penetrate bacteria due to synergism
penicillins stopping peptidoglycan cell wall synthesis allowing aminoglycosides to gain access to the cell interior, where they act on the 30S subunit of the bacterial ribosome
what are the two pathways of angioedema
mast cell activation (Type 1 hypersensitivity, direct mast cell activation- like opioids)
-associated pruritic and urticaria
excess bradykinin (ACEI, C1 inhibitor deficiency) -NO pruritic and urticaria
what type of hypersensitivity is acute hypersensitivity pneumonitis (and what causes it)
specific serum IgG antibodies that precipitate bacterial or fungal antigens found in inhaled organic dust particles
causes interstitial alveolitis and bronchiolitis via IMMUNE COMPLEX and COMPLEMENT DEPOSITION in vessel walls (Type III Hypersensitivity)
what causes a bruise to change color from bluish to greenish
HEME OXYGENASE (contained in macrophages and some other cells) degrades heme to BILIVERIDEN, CO, and Fe3+
biliveriden is GREEN in color and is further reduced (by biliverdin reductase) to bilirubin (yellow pigment) which is transferred to liver bound to albumin
what is seen in acute and chronic vitamin A toxicity (overdose)
Acute: nausea, vomiting, vertigo, blurred vision
Chronic: alopecia, dry skin, hyperlipidemia, hepatotoxicity, hepatosplenomegaly, visual difficulties
PAPILLEDEMA when present is suggestive of CEREBRAL EDEMA in the setting of bending intracranial hypertension (PSEUDOTUMOR CEREBRI)
large doses of vitamin C are associated with what
false negative stool guaiac results
diarrhea
abdominal bloating
maybe calcium oxalate nephrolithiasis
large doses of vitamin E are associated with what
higher mortality rates due to hemorrhagic stroke in adults
higher rates of necrotizing enterocolitis in infants
What is BLOOM syndrome
AR disorder of mutation in BLM gene that encodes for DNA HELICASE (enzyme responsible for unwinding of the double helix)
chromosomal instability and breakage manifesting as: GROWTH RETARDATION FACIAL ANOMALIES (microcephaly) PHOTOSENSITIVE RASH IMMUNODEFICIENCY (recurrent infections)
what prevents reannealing of the ssDNA during replication
ssDNA-binding proteins- they bind to and stabilize the ssDNA, preventing it fro reannealing
what does topoisomerase do
relieves tension in supercoils by introducing transient single- or double-stranded nicks in the DNA (located ahead of helices on the dsDNA segment of the relocation fork)
what is the treatment of choice for specific phobia
behavioral therapy (systematic, repeated exposure to the phobic stimulus)
typically done in a step-wise manner, resulting in decreased anxiety over time as habituation and extinction occur
can be done in vivo (most effective), imaginal, or virtual reality
cutaneous neurofibromas are predominately comprised of what
they are benign nerve sheath neoplasms made up mostly of SCHWANN CELLS (NEURAL CREST derivatives)
the neural tube gives rise to what
neurons of CNS neurohypophysis retina pineal gland preganglionic autonomic fivers astrocytes ependymal cells
the vertebrae are derived from what
paraxial mesoderm
the surface ectoderm gives rise to what
epidermis lens of eye outer layer of cornea nasal and oral epithelium olfactory epithelium inner ear sensory organs anal epithelium below the dentate line Rathkes pouch salivary, sweat, and mammary glands
what are acute dystonia and akathisia
acute dystonia:
- 3-4 days after starting
- distressing, sustained, involuntary contraction of the neck, mouth, tongue, or eye muscles
akathisia- physical restlessness, difficulty sitting still, compelling need to move
how does the kidney try and make up for metabolic acidosis
increased HCO3- resorption
increased H+ secretion
increased acid buffer excretion ((HPO4)2- and NH3 which get excreted as H2PO4- and NH4+)
what are PROTHROMBIN COMPLEX CONCENTRATES
contain the vitamin K-dependent factors II, VII, IX, and X
can be used in bleeding due to WARFARIN OVERDOSE (along with fresh frozen plasma)
what do aminocaproic acid and tranexamic acid do
inhibit fibrinolysis by inhibiting plasminogen activation (tPA, alteplase, reteplace, streptokinase, tenecteplase)
what anticonvulsants should be avoided in someone with juvenile myoclonic seizures (and all generalized epilepsy syndromes for that matter) and why
narrow-spectrum anticonvulsants (phenytoin, carbamazepine, gabapentin, phenobarbital)
they can aggravate seizures
what is used to treat juvenile myoclonic epilepsy (JME)
broad-spectrum anticonvulsant
VALPROIC ACID, lamotrigine, levetiracetam, topiramate
what is fluphenazine
dopamine antagonist (typical antipsychotic)
used to treat Tourette syndrome
in a patient with known mitral stenosis what finding in the heart is suggestive of aortic valve involvement too
left ventricular DIASTOLIC PRESSURE INCREASE
b/c this would be normal or decreased in mitral stenosis alone
what pressure changes does mitral stenosis cause
elevated left atrial diastolic pressure, therefore causing:
elevated pulmonary capillary wedge pressure
pulmonary hypertension
decreased pulmonary vascular compliance
right ventricular dilation
functional tricuspid regurgitation
where are the ethmoid air cell and when are they injruted
medial to the orbit
can be affected in BLOWOUT fractures of the orbits MEDIAL WALL
what is an inferior orbital blowout fracture
orbital contents spill into MAXILLARY SINUS
thin bone bordering MAXILLARY SINUS at inferior orbit
blunt trauma to the eye causes rapid increase in pressure that does not typically rupture the globe but is transferred into the orbit where weak points (inferior and medial) can blow out
acetylcholine release from presynaptic terminal vesicles at the NMJ depend on what
influx of extracellular calcium into the presynaptic terminal
calcium influx happens following depolarization and opening of voltage-gated calcium channels
what are the in utero CMV complciations
CHORIORETINITIS sensorineural deafness seizures jaundice hepatomegaly splenomegaly microcephaly
what sleep problems are seen in narcolepsy
shortened sleep latency
enter rapid eye movement sleep almost immediately
recurrent lapses into sleeps or naps (at least 3 times per week for 3 months)
hypocretin-1 (orexin) levels are low
what is hyper somnolence disorder
diagnosed when excessive and impairing daytime sleepiness cannot be explained by another sleep disorder
persistent daytime sleepiness rather than the “sleep attacks” seen in narcolepsy
these pts do not feel refreshed after naps
what are the effects of nitroprusside
BALACNED VASOdilator and VENOdilator
thus it decreases both preload and after load, and it is balances so SV is maintained
how does NOCARDIA present
sputum stain- weakly GRAM-POSITIVE, catalase-positive, rod-shaped bacteria that form partially acid-fast BRANCHING FILAMENTS
typically lung (cavitary pneumonia that looks like TB), brain, or skin manifestations in the immunocompromised
RING-ENHANCING focal lesion with surrounding edema
dyspnea, cough, fatigue, night sweats
fever, headache
transplant recipient on immunosuppressive therapy
lethargic w/ patchy lung crackles
increased leukocyte count
nodules but no parenchymal infiltrate on X-ray
what causes closure of epiphyseal plate (growth plate)
sex hormones (estrogen, testosterone)
what defines precocious puberty in Caucasian females
development of secondary sexual characteristics before after 7
excess steroids cause premature fusion of growth plate and full potential height is never reached
what are estrogens affects on the bone at sites other than the epiphyseal growth plate
anabolic
stimulate osteoblastic deposition and decrease osteoclastic bone resorption
low estrogen states (menopause), are associated with rapid bone loss
what is the role os somatomedin C (IGF-1) at the epiphyseal growth plate
proliferation of chrondocytes causing increase in linear growth
no effect on closure of the plate (which is why it can lead to gigantism)
what is teriparatide
recombinant molecule identical to the 34-amino-acid sequence at the N-terminal portion of endogenous PARATHYROID HORMONE
stimulates MATURATION of PRE-OSTEOBLASTS into bone-forming OSTEOBLASTS that lay down collagen and eventually mineralize the matrix
what does denosumad do
human monoclonal antibody to receptor activator of nuclear factor KappaB ligand (RANKL)
RANKL is part of the tumor necrosis factor family and is required for OSTEOCLAST function
what causes a lacunar infarct
ischemic stroke of SMALL PENETRATING VESSELS that supply the deep brain structures (basal ganglia, pons) and subcortical structures (internal capsule, corona radiata)
CHRONIC HYPERTENSION which predisposes arterioles to undergo lipohyalinosis, microatheroma formation, and occlusion (HYPERTENSIVE ARTERIOLAR SCLEROSIS)
smoking and diabetes are other risk factors
a lacunar infarct where causes PURE MOTOR hemiparesis
POSTERIOR limb of the INTERNAL CAPSULE or BASAL PONS
a lacunar infarct where causes PURE SENSORY stroke
VENTROPOSTEROLATERAL or VENTROPOSTEROMEDIAL THALAMUS
a lacunar infarct where causes ATAXIA-HEMIPLEGIA SYNDROME
POSTERIOR LIMB of INTERNAL CAPSULE or BASAL PONS
a lacunar infarct where causes DYSARTHRIA-CLUMSY HAND SYNDROME
GENU of the INTERNAL CAPSULE or BASAL PONS
brain arteriovenous malformations typically present how
intracranial hemorrhage in children
what is a Charcot-Bouchard Aneurysm
ypcially caused by CHRONIC HYPERTENSION and results in hemorrhagic stroke involving deep brain structures (basal ganglia, cerebellar nuclei, thalamus, pons)
hemorrhage would appear as a focus of INTRAPARENCHYMAL HYPERDENSITY on the initial CT scan
what is the most common cause of spontaneous lobar/cortical hemorrhage (occipital, partial) in the elderly
cerebral amyloid angiopathy
what is seen in chronic RENAL ALLOGRAFT rejection
gradual deterioration in graft function that occurs at least 3 months post-transplant in the absence of other precipitating events (active acute rejection, withdrawal of immunosuppression)
characterized by WORSENING HYPERTENSION, a PROGRESSIVE RISE in serum CREATININE, and proteinuria with normal urine sediment
mediated by a chronic, indirect immune response against donor allo-antigens and results int OBLITERATIVE INTIMAL THICKENING
vascular fibrinoid necrosis and neutrophil infiltration of the arterioles, glomeruli, and peritubular capillaries are characteristic of what type of transplant rejection
hyper acute rejection of a renal allograft
a dense interstitial mononuclear infiltrate is characteristic of what kind of transplant rejection
ACUTE cellular rejection
typically happens within 6 months of procedure but can occur later if immunosuppressants are stopped
what is hydralazine
direct vasodilator often used in combo with isosorbide dinitrate for treatment of heart failure
ADRs: tachycardia and orthostatic hypotension
what are the effects of prolonged portal hypertension (say to do cirrhosis)
varices at the 4 sites of portocaval anastomoses (esophagus, rectum, umbilicus, and retroperitoneal)
ascites
who is ascites (secondary to liver cirrhosis) treated
resting sodium intake and diuretics (furosemide and sptinolactone in combo is most common prescription)
what is the most common eye involvement of diabetes
unilateral CN III involvement (DIABETIC CNIII MONONEUROPATHY)
what is diabetic CN III MONONEUROPATHY
due to ISCHEMIC NERVE DAMAGE
acute onset DIPLOPIA
“DOWN and OUT” position of eye
PTOSIS (paralysis of levator palpebrae)
PUPILLARY SIZE and REACTIVITY is NORMAL (major key b/w this and compression of CNIII)
diabetic mononeuropathies are cased by what
ischemic nerve damage
what are the upper motor neuron signs
spastic paralysis
clasp-knife rigidity
hyperreflexia
babinski sign
what are the lower motor neuron signs
flaccid paralysis
hypotonia
hyporeflexia
muscle atrophy and fasciculations
what is MYOCARDIAL HIBERNATION
state of CHRONIC MYOCARDIAL ISCHEMIA in which both myocardial metabolism and function are reduced to mach a concomitant reaction in coronary blood flow (due to moderate/severe flow-limiting stenosis)
new equilibrium prevents necrosis
chronically hibernating myocardium demonstrates decreased expression and disorganization of contractile and cytoskeletal proteins, altered androgenic control, and reached calcium responsiveness
changes lead to DECREASED CONTRACTILITY and LV SYSTOLIC DYSFUNCTION
coronary REVASCULARIZATION and subsequent RESTORATION of BLOOD FLOW to hibernating myocardium IMPROVES CONTRACTILITY and LV FUNCTION
what is ischemic preconditioning
phenomenon in which brief repetitive episodes of myocardial ischemia, followed by reperfusion, protect the myocardium from subsequent prolonged episodes of ischemia
ex: repetitive episodes of angina before MI can delay cell death after complete coronary occlusion and therefore provide greater time for myocardial salvage with coronary revascularization
what is ventricular remodeling
change in the structure (cardiac mass and dimensions) or function of the heart in response to cardiac injury or hemodynamic changes (pressure/volume overload)
can occur in long-term myocardial hibernation, but takes weeks to months to recover following reperfusion therapy
what is seen with an OBSTRUCTION of the RIGHT BRACHIOCEPHALIC (INNOMINATE) VEIN
could be due to external compression by an apical lung tumor or thrombotic occlusion as can occur with central catheter placement for extended period of time
formed by union of right subclavian vein and the right internal jugular vein
right external jugular drains into right subclavian and thus obstruction can cause venous congestion of structures drained by external jugular vein
DRAINS RIGHT LYMPHATIC DUCT: which drains lymph from right upper extremity, the right face and neck, the right hemithroax, and the right upper quadrant of the abdomen
-blockage of this = SWELLING
both brachiocephalic veins join to form SVC (compressed both sides of face swollen in SVC SYNDROME)
intravascular hemolytic anemias are characterized by what lab findings
DECREASED serum HAPTOGLOBIN
INCREASED LDH and BILIRUBIN
what is haptoglobin
serum protein that binds free hemoglobin and promotes its uptake by the reticuloendothelial system
levels decrease when significant quantities of hemoglobin are related in the circulation (like in INTRAVASCULAR HEMOLYSIS)
decreased reticulocyte could in the presence of anemia is characteristic of what?
APLASTIC anemia
what is thought to cause atopic dermatitis
mutations affecting proteins such as filaggrin or other components of the epidermis, resulting in IMPARIEMTN of the SKIN’S BARRIER FUNCTION
this increases the immunologic exposure to environmental allergens and microbial antigens, leading to immune hypersensitivity
affected patients have HIGH serum IgE levels, peripheral EOSINOPHILIA, and high levels of cAMP PHOSPHODIESTERASE in their leukocytes
