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NBME 13 (Explanations)
Terms in this set (94)
progressive weakness, dec strength, hand muscle atrophy, diffuse hyperreflexia and fascicultations on hands and arms, normal sensory exam;
amyotrophic lateral sclerosis (ALS)
--death of both upper and lower motor neurons in the motor cortex of the brain, the brain stem, and the spinal cord
--Stephen Hawking disease
UMN and LMN signs
--rapidly progressive weakness with fasciculations eventually leading to muscle atrophy, spasticity, dysarthria, dysphagia, respiratory compromise, death from respiratory failure
UMN vs LMN weakness
--UMN weakness (brain to spinal cord) manifests in hyperreflexia and rigid muscle tone, positive Babinski sign
--LMN weakness (anterior horn to muscle) manifests in muscle atrophy, decreased reflexes, fasciculations, and flaccid muscle tone
history of numbness of fingers on left hand, loss of touch graphesthesia, loss of two point discrimination in left hand
--lesion in somatosensory cortex on contralateral side (right hemisphere)
--graphesthesia is the ability to sense what is being drawn or written via touch on their hand
--the postcentral gyrus is a prominent structure in the parietal lobe of the human brain; it is the location of the primary somatosensory cortex, the main sensory receptive area for the sense of touch
missense mutation of tyrosine kinase domain of TrkA gene disrupts what process?
phosphorylation of downstream molecules in response to nerve growth factor
--A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases are a subclass of protein kinase.
--The presence of this kinase leads to cell differentiation and may play a role in specifying sensory neuron subtypes. Mutations in this gene have been associated with congenital insensitivity to pain with anhidrosis, self-mutilating behavior, mental retardation and cancer
this part of the brain is affected most in chronic alcoholics
--a lesion in the vermis causes truncal ataxia, gait ataxia, and dysarthria
suppression vs. repression
suppression: mature defense
suppression is the voluntary withholding of an idea of feeling from conscious awareness, like not thinking about an exam until the week of it or doctor controlling anger at alcoholic pts he doesnt like
repression: immature defense
repression is someone involuntarily withholding something from consciousness like not remembering going to counseling for parents divorce
replace a bad/warded off feeling/idea with an emphasis on its opposite; someone with libidinous thoughts enters a monastery
mature reaction formation; replacing unacceptable wish with action similar to wish but does not conflict with their values, like teens aggression toward father redirected to perform well in sports
elderly woman with 1mo hx of urinary frequency and urgency, 3mo hx of walking difficulty, problems with conversation and memory; normal strength and sensation; mini cog average-normal; wide shuffling gait; ct shows enlarged ventricles
normal pressure hydrocephalus
wet, wobbly, wacky
triad of urinary incontinence, ataxia, cognitive dysfunction
--expands ventricles that distort fibers of the corona radiata that lead to dementia, ataxia, urinary incontinence
--does not increase subarachnoid space volume
--common in elderly and idiopathic
IHC positive for chromogranin indicates cancer of what origin?
neuroendocrine or carcinoid
10% of pheochromocytomas are extraadrenal, occurring in
sites such as the organ of Zuckerkandl and the carotid
body, where they usually are called __
paragangliomas, rather than pheochromocytomas
Pheochromocytomas usually subscribe to a convenient
rule of 10s
--10% of pheochromocytomas are extraadrenal, occurring in
sites such as the organ of Zuckerkandl and the carotid
body, where they usually are called paragangliomas, rather than pheochromocytomas.
--10% of adrenal pheochromocytomas are bilateral; this proportion may rise to 50% in cases that are associated with familial syndromes.
--10% of adrenal pheochromocytomas are malignant, although the associated hypertension represents a serious and potentially lethal complication of even benign tumors. Frank malignancy is somewhat more common in tumors
arising in extraadrenal sites.
--One "traditional" 10% rule that has since been modified
pertains to familial cases. It is now recognized that as
many as 25% of persons with pheochromocytomas and paragangliomas harbor a germ line mutation in one of at least six known genes,
On microscopic examination, pheochromocytomas are
polygonal to spindle-shaped chromaffin cells
and their supporting cells, compartmentalized into small
nests, or Zellballen, by a rich vascular network
winging of scapula when pressing arms against a wall; inability to anchor scapula to thoracic cage & cannot abduct arm above horizontal position
injury to long thoracic nerve and muscle deficit in serratus anterior
--usually occurs after axillary node
dissection after mastectomy, stab wounds
"worst headache of my life" and nuchal rigidity, confusion, lethargic; bright white areas on CT
unable to flex elbow against gravity suggests nerve lesion at
musculocutaneous nerve, which supplies biceps and brachialis muscles responsible for elbow flexion
pt with intense stabbing pain behind eye, 1 hour after going to bed and lasts 1 hour; same side nasal stuffiness and tearing from eye during pain; long history at same time every day
--unilateral headache and tearing and rhinorrhea
--symptoms occur regularly everyday at the same time and same period over years
which nerve may be cut to decrease stomach acid output and decrease the likelihood of ulcers forming in the jejunum at its junction with the stomach?
people can reduce their risk of type 2 DM with a __ diet
low calorie, fat <30%
Japanese and those with a traditional Japanese diet are at increased risk for __ because of __
carcinogens: nitrosamines in smoked foods
newborn with frantic sucking, inconsolable crying, stimuli overreaction, excessive startle response; resolves over 2-3 weeks
heroin withdrawal: hyper-excitability and increased sympathetic discharge
sickle cell disease mutation, pathophysiology, crisis symptoms
--sickle cell is due to a point mutation in 6th codon of beta chains causing substitution of glutamate with valine
--sudden fever, severe rib pain or local pain, tenderness, sickle cells on peripheral blood smear
--sickle cell Hb polymerizes under hypoxic conditions due to amino acid substitution on beta chain
after gene transcription, pre-mRNA is performed; what is required on pre-mRNA and must happen for pre-mRNA to be processed into mRNA?
--pre-mRNA has a AATAAA sequence at the end
--this sequence forms a part of the recognition signal for
endonucleolytic cleavage and polyadenylation (addition of~200As)
that is required for processing into mRNA
--polyadenylation protects the molecule from degradation and aid transport to cytoplasm
--this defect in the beta globin gene causes beta globin chains to decrease and beta thalassemia
interrupting the 3 CCA end of tRNA will disrupt this process
cannot charge tRNA with amino acid effectively, therefore disrupting protein synthesis
how do epi and glucagon work during hypoglycemia?
--glucagon from the liver (to glucagon receptor) and epinephrine from the liver/muscle (to beta receptor) work the same way to activate adenylate cyclase
--a. cyclase activates PKA (ATP > cAMP)
--PKA activates glycogen phosphorylase kinase
--GPK activates glycogen phosphorylase, which breaks glycogen into glucose
how does epi work during hypoglycemia when it binds to alpha receptors in muscle?
--activates alpha receptor
--releases calcium from ER
--calcium-calmodulin interact during muscle contraction
--calcium and calcium-calmodulin both activate GPK
--GPK activates GP, which breaks down glycogen into glucose
how does insulin work during hyperglycemia/fed state?
--insulin binds tyrosine kinase dimer receptor in liver and muscle
--this activates protein phosphatase and glucagon synthase
--protein phosphatase further activates glucagon synthase and inhibits glycogen phosphorylase
--glucagon synthase makes glucose into glycogen
*note PKA, activated during hypoglycemia, inhibits glycogen synthase and promotes glycogen phosphorylase; protein phosphatase, activated during fed state, promotes glycogen synthase and inhibits glycogen phosphorylate
PKA, activated during hypoglycemia, inhibits __ and promotes __; protein phosphatase, activated during fed state, promotes __ and inhibits __
man with a good diet and hashimoto thyroiditis presents with megaloblastic anemia, weakness, light headedness, pallor, inc mma and homocysteine
--failure of intrinsic factor production, necessary for B12 absorption
--megaloblastic anemia caused by atrophic gastritis, parietal cell loss, and lack of intrinsic factor
pt rbcs have spiny projections, low total serum cholesterol; symptoms of malnutrition like weakness, ataxia, loss of dtr's, retinitis pigmentosa
Abetalipoproteinemia, or Bassen-Kornzweig syndrome
--rare autosomal recessive disorder that interferes with the normal absorption of fat and fat-soluble vitamins from food
--It is caused by a mutation in microsomal triglyceride transfer protein resulting in deficiencies in the apolipoproteins B-48 and B-100, which are used in the synthesis and exportation of chylomicrons and VLDL respectively
-Micrograph showing enterocytes with a clear cytoplasm (due to lipid accumulation) characteristic of abetalipoproteinemia. Duodenal biopsy. H&E stain.
female passes genetic mutations to all children, though mutations more severe in children than herself
acetazolamide is a carbonic anhydrase inhibitor that may be used for short periods for altitude sickness but pt must watch out for __
hypovolemia and orthostatic hypotension; acetazolamide is a weak diuretic but can cause these if used for a prolonged time
loud harsh holosystolic murmur at left sternal border, palpable thrill, 3yo child
ventricular septal defect, loudest at tricuspid area
CHF with edema, diffuse moist crackles; what are atrial myocytes secreting?
hypervolemic so secreting renin release inhibitors; renin is released in hypovolemic situations to increase renal blood flow
painful edema of extremity after removing lymph nodes
lymphedema; treat with compression sleeve
most common cardiac tumor in adults and famous source of embolism; suspect this when pt has thrombus removed and shows mesenchymal cells in abundant ecm confirming cardiac tumor
myxoma, usually in left atrium
why does gemfibrozil with simvastatin cause myalgia?
simvastatin byproducts in the blood can cause myalgia; gemfibrozil is a cp450 inhibitor that can raise simvastatins byproduct blood levels by blocking their metabolism/glucuronidation
the biggest side effect from taking metformin, especially in toxic doses:
lactic acidosis; this is why metformin is contraindicated in renal failure
one allele out of two is inactivated & causes cancer
loss of heterozygosity: the functional allele is lost from a TSG so the TSG is no longer effective, causing oncogenesis
disc shaped yeast on silver stain of diffuse interstitial lung infiltrate, HIV positive
man with reduced sperm motility, chronic sinusitis, bronchiectasis, situs inversus
--defective dynein or absence
this drug treats trematode and cestode infections by increasing the permeability of their cell membranes to calcium, causing paralysis, dislodgement, and death of the parasite
broad-spectrum anthelmintic, effective against roundworms, tapeworms, and flukes including: giardiasis, trichuriasis, filariasis, neurocysticercosis, hydatid disease, enterobiasis, and ascariasis
--degenerative alterations in the intestinal cells of the worm by binding to the colchicine-sensitive site of tubulin, thus inhibiting its polymerization or assembly into microtubules
--the loss of the cytoplasmic microtubules leads to impaired uptake of glucose by the larval and adult stages of the susceptible parasites, and depletes their glycogen stores.
--Degenerative changes occur in the endoplasmic reticulum, the mitochondria of the germinal layer, and the subsequent release of lysosome.
Vd = .35
Initial peak serum conc = 8
Pt weight = 55 kg
LD = .35 x 8 = 2.8mg/kg x 55kg = ~150mg
increased ACTH secretion by a pituitary adenoma can cause Cushing syndrome due to
cortical hyperplasia; hyperplasia of cells in zona fasciculata of adrenal gland
a benign hemangioma in a newborn originates from this tissue
endothelium: mesenchyme blood vessels can turn into a hemangioma
connects ovaries to lateral pelvic wall and contains ovarian vessels
pt using corticosteroids for past 2 years gets arthritis/joint collapse
aseptic necrosis; known side effect of corticosteroid use
flank pain after appendectomy and right ovarian resection; menses, vitals, normal; pain most likely due to
accidental ligation of ureter; the ureter is at risk of injury during ligation of ovarian vessels in ovariectomy
hip adductors (allow you to stand up from sitting insert mostly on the femur from the
newborn with nonbilious projectile vomiting, fast prominent peristalsis, metabolic alkalosis
hypertrophy of the pyloric sphincter
Paramesonephric (muillerian) ducts
early precursors to female reproductive structures (oviducts, uterus, and upper vagina)
connects cervical region/uterus posteriorly
decreasing urine output following IV gentamicin for 2 weeks; muddy brown granular casts
acute tubular necrosis: renal ischemia triggers hypoxic changes in tubular epithelial cells, especially proximal tubules and thick ascending limb of loop of henle, decreasing functional capacity with brown casts
--hx exam of pts kidneys would show necrotic cells in proximal tubule most likely
why are pts deficient in myeloperoxidase more susceptible to recurrent fungal infections?
inability to produce hydroxy-halide radicals: MPO is found in azurophilic granules of neutrophils, which in the presence of a halide such as Cl converts H2O2 to HClO (potent antimicrobial)
--MPO deficiency is usually asymptomatic or presents with recurrent yeast infections ie candida albicans
--diabetics have increased risk of developing yeast infections
how do neutrophils make hypochlorite, a potent antimicrobial?
MPO converts H2O2 with Cl to HClO
function of HIV viral protease
--viral RNA is translated into a polypeptide sequence and assembled in a long chain including proteins reverse transcriptase, protease, integrase
--before enzymes are functional they must be cut/processed
--viral protease cuts long chain into individual enzyme components which then facilitate production of new viruses
inhibition of viral protease leads to lack of a mature core
pt with EBV infection has atypical cells in peripheral blood smear with abundant lacey cytoplasm
reactive cytotoxic T lymphocytes reacting to B cells
--aka Downey cells: note weird cytoplasm
urethritis, sexually promiscuous pt; cultures grow on chocolate, gram stain shows gram negative diplococci; what is the organism and its virulence factors?
psoriasis, ankylosing spondylitis, IBD, Reiters syndrome are linked diseases due to
HLA-B27, a class I MHC; analysis of class I MHC allele expression can evaluate susceptibility to these diseases
pt in 30s with back pain and joint stiffness, improves after mild exercise; fatigue and weight loss; x ray of sacroiliac joint confirms diagnosis
Ankylosing spondylitis is a chronic inflammatory disease of the axial skeleton, with variable involvement of peripheral joints and nonarticular structures. AS is one of the seronegative spondyloarthropathies and has a strong genetic predisposition. (HLA-B27)
--The most common symptom of AS is low back pain. It mainly affects joints in the spine and the sacroiliac joint in the pelvis. In severe cases, complete fusion and rigidity of the spine can occur.
--"Bamboo spine" develops when the outer fibers of the fibrous ring of the Intervertebral discs ossify, which results in the formation of marginal syndesmophytes between adjoining vertebrae.
--AS typically begins in the second or third decade of the person's life and occurs more often in males.
the most important and effective measure in preventing nosocomial infections
hand cleansing before and after each medical personnel visit
elderly man with increasingly severe back pain, weight loss, pain esp at night worse with movement, not relieved by aspirin; point tenderness over lumbar area with 4+ protein in urinalysis
--cancer of plasma cells; collections of abnormal plasma cells accumulate in the bone marrow, where they interfere with the production of normal blood cells.
--most cases of multiple myeloma also feature the production of a paraprotein, an abnormal antibody which can cause kidney problems
--bone lesions and hypercalcemia (high blood calcium levels) are also often encountered.
CRAB: C = Calcium (elevated), R = Renal failure, A = Anemia, B = Bone lesions.
--Myeloma has many other possible symptoms, including opportunistic infections (e.g., pneumonia).
pt in 40s has autoimmune disorder causing proximal muscle weakness of lower extremities; in this disease, autoantibodies to __ channels cause the weakness
Lambert-Eaton syndrome/myasthenic syndrome
--autoantibodies to presynaptic calcium channels
--decreases ACh release and causes proximal muscle weakness
20yo with hemoptysis, hematuria, weight loss over 3 months; hypochromic microcytic anemia
--antibodies attack BMs causing crescentic glomerulonephritis with linear IF and alveolar damage
--light microscopy will show glomerular crescents
--linear IgG and C3 deposition in glomerular BM
--no deposits seen on EM
bence jones proteins
Bence Jones proteins are particularly diagnostic of multiple myeloma in the context of end-organ manifestations such as renal failure, lytic (or "punched out") bone lesions, anemia, or large numbers of plasma cells in the bone marrow of patients. Bence Jones proteins are present in 2/3 of multiple myeloma cases.
The proteins are immunoglobulin light chains (paraproteins) and are produced by neoplastic plasma cells.
what mechanism causes hypercalcemia in multiple myeloma?
local IL-1 and TNF effects activate osteoclasts which cause bone resorption and subsequent hypercalcemia
acetazolamide mechanism, use, toxicity
--carbon anhydrase inhibitor causes self-limited NaHCO3 diuresis and reduces total body HCO3 stores; inhibits bicarbonate reabsorption and hydrogen ion secretion in the proximal tubule
--use in glaucoma, altitude sickness, urinary alkalinization, metabolic alkalosis, pseudotumor cerebri
--tox: hyperchloremic metabolic acidosis, paresthesias, NH3 toxicity, sulfa allergy
scleroderma pts have difficulty swallowing due to
decreased peristalsis and lower esophageal sphincter tone
A disease in which postsynaptic nicotinic acetylcholine receptors on muscle cells are destroyed so that muscles can no longer respond to the acetylcholine signal to contract. Symptoms include muscular weakness and progressively more common bouts of fatigue. The disease's cause is unknown but is more common in females than in males; it usually strikes between the ages of 20 and 50.
Anticholinesterase prolongs activity of ACh in synaptic space. Used for Post op ileus and urinary retention, myasthenia gravis and reversal of NMJ blockade (post op). NO CNS penetration.
pt with MG doubled dose of neostigmine from feeling very weak; weakness increased; why?
overdosage of Anti-AChE desensitized postsynaptic nicotinic receptors
MG is due to autoimmune deactivation of nicotinic receptors
classic paraneoplastic symptoms of small intestine carcinoic tumor
wheezing, right sided heart murmurs, diarrhea, flushing, inc 5HIAA in urine, niacin deficiency/pellagra
--note rosettes in hx
pt weaker as day goes on, difficulty breathing deep breaths with decreased vital capacity, tidal volume, and expiratory reserve volume but normal residual volume
burning urination, uterine prolapse, mild inc in leukocytes, bilateral dilation of renal collecting system; greatest risk for
pyelonephritis: UTI can ascend to kidneys
vasoactive intestinal polypeptide
increased by parasympathetic nervous system to increase water and electrolyte secretion while relaxing intestinal smooth muscles and sphincters; if pt is dehydrated and rehydrated, parasympathetics kick in with VIP
young child with puffy eyes, recent URI, 3+ protein urine, no cells or casts
minimal change disease: most common cause of nephrotic syndrome in children usually after URI or immunization
--effacement of foot processes of podocytes and loss of negative glomerular charge; thus protein in urine and edema (puffy eyes)
diabetic with normochromic normocytic anemia with chronic renal disease (high creatinine and BUN); what is appropriate therapy for anemia?
epo; epo is usually made in kidneys in response to hypoxia but diabetic nephropathy inhibits this
elderly women with bloody diarrhea and pain; hx of cerebral infarction, watery stool with red blood, patchy ulceration at splenic flexure on colonoscopy
the splenic flexure is a watershed area between middle and left colic arteries that is most commonly affected in ischemia, plus hx of atherosclerosis/previous infarction = ischemic colitis
elderly man with increasingly severe abdominal pain, diarrhea, loss of appetite, fever, rebound tenderness and distention in left lower quadrant; CT shows thickened colonic wall and pericolic fat inflammation with contrast collection
diverticulitis: old age, left lower quadrant pain, fever, typical CT findings
the most beneficial drug in hepatic encephalopathy to improve mental status
lactulose: traps ammonium in intestines by generating NH4+
Defective decidual layer allows placenta to attach to myometrium. No separation of placenta after birth. Prior C-section, inflammation, and placenta previa predispose. MASSIVE BLEEDING after delivery. Accreta = encased in.
Premature detachment of placenta from implantation site. Fetal Death. May be associated with DIC. Increased risk with smoking, hypertension, cocaine use (vasoconstriction). Presents with PAINFUL bleeding in the 3rd trimester.
a placental condition in which chorionic plate of the placenta is smaller than the basal plate, the margin is raised with a rolled edge, rolls over itself
Extra placental lobe implants at some distance from rest of placenta
Chronic inflammatory infiltrate of the placental villi composed of plasma cells, lymphocytes and histiocytes or macrophage
When the syncytiotrophoblast barrier is broken, maternal inflammatory cells are able to invade placental tissue (chorionic villi), possibly causing uteroplacental insufficiency over time. Intravillous maternal T-lymphocytes and increased fetal histiocytes (called Hofbauer cells). Often caused by TORCHES organisms or alloimmune processes.
paraneoplastic hormone excess: labs show hyponatremia and decreased plasma osmolality and increased urine osmolality
young women with history of hypercoagulability, miscarriage, prolonged PTT
antiphospholipid antibody syndrome
hypoxemic respiratory failure, bx shows acute lung injury, what else may suggest this is ARDS?
diffuse alveolar damage: alveolar hyaline membrane, edema, hemorrhage, heavy firm lungs
therapy for newborn with persistent pulmonary hypertension
nitric oxide: reduces pulmonary vascular resistance in infants with hypoxic respiratory failure with no diaphragmatic hernia
treatment for idiopathic infertility in a woman
clomiphene: partial estrogen agonist; inhibits stronger estrogens negative feedback on gonadotropin secretion, enhancing their release and stimulating ovulation
+ intrauterine insemination
treating warfarin toxicity
--mild: vitamin K (replenish factors II, VII, IX, X)
--severe: fresh frozen plasma
infertile man with low semen fructose suggests deficient activity in:
Fructose is androgen-dependent and is produced in the seminal vesicles. Fructose levels should be determined in any patient with azoospermia and especially in those whose ejaculate volume is less than 1 ml, suggesting seminal vesicle obstruction or atresia. Absence of fructose, low semen volume, and failure of the semen to coagulate indicate either congenital absence of the vas deferens and seminal vesicles or obstruction of the ejaculatory duct.
What is the immunoglobulin responsible for hypersensitivity reaction?
what are examples of stress-related diseases?
What is the function of immunization?
What are some signs & symptoms of Cushing's disease?
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