uWorld 20 Flashcards
where does heme synthesis occur
what are the principle sites of heme synthesis
partially in CYTOPLASM and partially in MITOCHONDRIA (first and final three steps)
erythrocyte precursor cells (located in the bone marrow) and hepatocytes (use heme in microsomal CYP450 system)
what happens when erythrocytes lose their mitochondria
lose ability to generate heme and therefore hemoglobin
what are PaO2, SaO2, and oxygen continent in cyanide poisoning
all are normal
venous oxygen octane raises and the arterial-venous oxygen gradient falls
what are PaO2, SaO2, and oxygen continent at high altitude
all are decreased
what are PaO2, SaO2, and oxygen continent in obese patients
hypoventilation due to reduced chest wall compliance
increased lower lobe perfusion (V/Q mismatch)
all decrease and CO2 content increases
what are PaO2, SaO2, and oxygen continent in anemia
and what is a common cause of anemia in premenopausal women
O2 content decreased but PaO2 and SaO2 are normal
chronic blood loss secondary to menstruation
what are the toxins of C. diff, which is more virulent, and in what way do they both work
toxin A (enterotoxin) toxin B (cytotoxin)- more virulent both toxins INACTIVATE Rho-REGULATROY PROTEINS involved in signal transduction and ACTIN CYTOSKELETON STRUCTURE maintenance as a result, the toxins cause DISRUPTION of INTERCELLULAR TIGHT JUNCTIONS leading to cell rounding/retraction as well as increased (paracellular) intestinal fluid secretion
what happens to RPF and GFR in a hypovolemic state (i.e.. diarrhea and vomiting for 24 hours)
reduced ↓↓RPF and ↓GFR and thus reduced FF (FF = GFR/RPF)
leads to compensatory efferent arteriolar vasoconstriction,w which raises the filtration fraction and maintains GFR at near normal (but still decreased) levels. As RPF continues o decline, increasing glomerular oncotic pressure will eventually overwhelm he compensatory increase in hydrostatic pressure, leading to a precipitous drop in GFR
what is polymyositis
autoimmune disease that occurs due to CD8+ lymphocyte-mediated skeletal muscle damage and usually presents with symmetric proximal muscle weakness
what is aldosterone escape
despite increase in sodium absorption, hypernatremia and pedal edema are rarely observed in hyperaldosteronism
increased intravascular volume causes increased renal blood glow (with resulting pressure natriuresis) and augmented release of atrial natriuretic peptide
this limits net folium retention and prevents the development of overt volume overload and significant hypernatremia
what are the sodium, potassium, and bicarb levels in primer hyperaldosteronism
sodium: normal (aldosterone escape)
potassium: low
bicarb: high (metabolic alkalosis)
when would one see hypernaremia, hypokalemia, and metabolic acidosis
diarrhea (loss of water, K+, and HCO3- in the stool)
when would one see hypotension, hyperkalemia, hyponatremia, and metabolic acidosis
primary adrenal insufficiency (increased sodium loss, reached urinary exertion of K+ and H+ due to low aldosterone activity)
how does hyperaldosteronism work
increased Na+ reabsorption form the collecting tubule
creates a negative charge in the lumen, pulling K= and H+ from fibular cells and leading to increased excretion of urinary K+ and H+
aldosterone escape- stops hypernatremia and pedal edema
what DNA pol is the only one with 5’ to 3’ exonuclease activity, what does this allow it to do?
DNA POLYMERASE I
used to remove RNA rimer synthesized by RNA primase
all 3 PROKARYOTIC DNA polymerases have the ability to do what
3’ to 5’ EXONUCLEASE (“PROOFREADING”) activity
allows them to be capable of REOVING MISMATCHED NUCLEOTIDES
what temporarily cleaves both strands of the DNA double helix and introduces negative supercoils into he circular DNA to relieve tension created during strand unwinding
topoisomerase II (DNA grase)
what promotes unwinding and dissociation of parent DNA strands at the replication fork
helicase
selective ARTERIOLAR VASODILATORS (hydrazine, minoxidil) lower blood pressure by reducing systemic vascular resistance. this is limited by what
reflex SYMPATHETIC ACTIVATION and stimulation of the RENIN-ANGIOTENSIN-ALDOSTERONE axis results in SODIUM and FLUID RETENTION with peripheral edema
and TACHYCARDIA
what does the PCA supply
CN III and IV
thalamus, medial temporal lobe, selenium of the corpus callous, parahippocampal gyrus, fusiform gyrus, and occipital lobe
how does PCP (the drug) work
NMDA antagonist that is a hallucinogen
dissociative symptoms (detachment and withdrawn)
violent behavior
nystagmus (horizontal and vertical)
what happens to ventilation, perfusion, and V/Q mismatch form apex to base of lung
perfusion and ventilation increase at the base of lungs b/c of gravity
perfusion in crease is greater thus V/Q ratio DECREASED from apex to base
describe the blood flow in the 3 zones of the lung
zone 1 (apex): does not occur under physiological conditions (Palv greater then Part greater than Pven)
Zone 2: higher areas of lung where blood flows in a pulsatile fashion (Part greater than Palv greater than Pven)
zone 3: lower areas of lung where blood flows continuously (Part greater than Pven greater than Palv)
in supine lung is ALL ZONE 3 (gravity)
what is the difference b/w mania and hypomania
hypomania has lesser degree of severity and functional impairment and the absence of psychosis
ppl who are hypomanic have noticeable behavior charge but are often very productive
what are neurophysins
carrier proteins for oxytocin and vasopressin (ADH)
unique neurophysins carrier oxytocin and ADH from site of production in PARAVENTRICULAR and SUPRAOPTIC NUCLEI to the posterior pituitary
point mutations in neurophysin II underlie most cases of what
hereditary hypothalamic diabetes insipidus (disorder resulting form insufficiency ADH please into the systemic circulation
pulmonary artery occlusion pressure is measured at the distal tip of the pulmonary artery catheter after an inflated ballon occludes flow through a pulmonary artery branch
this closely corresponds to what
left atrial and left ventricular end-diastolic pressure
what are the best methods for diagnosing type I diabetes
FASTING GLUCOSE (over 126 mg/dL) HEMOGLOBIN A1C (over 6.5%) random glucose (over 200) oral glucose tolerance test (expensive and less convenient than other options)
oral glucose test is the preferred screening methods for what
gestational diabetes and cystic fibrosis related disease
matching is a method generally used in the design stage of case-control studies to control what kind of bias
CONFOUNDING
initial step of matching involves selecting variables that could be confounders (age, race, gender, smoking)
cases and controls are then selected based on the matching variables so that both groups have a SIMILAR DISTRIBUTION in accordance with the variables
where are parietal cells found in the gastric mucosa
UPPER GLANDULAR LAYER
OXYNTIC (pale pink)
the deeper aspect of the gastric glands has what
preponderance of small, basophilic, granular CHIEF CELLS that synthesize and secrete pepsinogen
what are causes of vitamin A deficiency
pancreatic insufficiency (chronic pancreatitis, cystic fibrosis) cholestatic liver disease/ BILIARY OBSTRUCTION (primary biliary cirrhosis) intestinal malabsorption (IBD, bariatric surgery) insufficient dietary intake
what is the ocular manifestation of rheumatoid arthritis
episcleritis or scleritis
usually presents as ocular discomfort
what is the ocular manifestation of sickle cell
retinopathy due to micro vesicular occupation, retinal ischemia, and neovascualrization/hemorrhage
vasoocclusive symptoms too usually at this stage (lung disease)
what is borezomib
inhibits 26S proteasome
can facilitate apoptosis of neoplastic cells by preventing degradation of pro-aporptoci factors in multiple myeloma
what is mycophenolate
reversibly inhibits a critical step in de novo purine nucleotide synthesis (inosine monophosphate dehydrogenase), which is required for proliferation of activated lymphocytes
selectively targets lymphocytes, reducing B and T cell proliferation and antibody production while promoting T cell apoptosis
ssDNA → dsDNA template → ssDNA progeny is the replication cycle of what virus
parvovirus
dsDNA → dsDNA template → dsDNA progeny is the replication cycle of what virus
adenovirus, poxvirus, herpesvirus
dsDNA → +RNA template → dsDNA progeny is the replication cycle of what virus
hepadnavirus (HBV)
ssRNA → -RNA template → ssRNA progeny is the replication cycle of what virus
poliovirus
ssRNA → dsDNA template → ssRNA progeny is the replication cycle of what virus
retroviruses
ssRNA → +RNA template → ssRNA progeny is the replication cycle of what virus
influenza, measles, rabies
what are the common medical conditions with POLYGENIC INHERITANCE
androgenic alopecia epilepsy glaucoma hypertension ischemic heart disease schizophrenia TIIDM
what is male pattern baldness
androgenic alopecia
most common type of hair loss in both males and females
POLYGENIC INHERITANCE
Ch 20, X, and Y
what is the dandy walker malformation
HYPOPLASIA/ABSENCE of CEREBELLAR VERMIS and CYSTIC DILATION of the FOURTH VENTRICLE with posterior fossa enlargement
non-communicating HYDROCEPHALUS may occur due to areas of the formina of Luschka and Magendie (nausea vomiting)
agenesis of corpus callous and malformation of faces, heart, limbs
DEVELOPMENTAL DELAY and PROGRESSIVE SKULL ENLARGEMENT
what is Arnold-Chiari malformation (Chiari II malformation)
downward displacement of the cerebellar vermis and tonsils below the foramen magnum
spinal myelomeningocele usually present
how is a brain arteriovenous malformation present
age 10-30
intracranial hemorrhage, seizure, headache, or focal neurologic hemorrhage
what is hypoxic-ischemic brain injury
may occur with complicated deliveries (emergency cesarean section)
typically presents with ALTERED CONSCIOUSNESS and decreased spontaneous MOVEMENTS during the neonatal period
watershed necrosis of the gray matter b/w perfusions zones of major cerebral arteries
high potency (neurological) 1st generation antipsychotics (Haloperidol and fluphenazine) side effects
extrapyramidal signs (acute dystonia, akathisia, parkinsonism)
low potency (non-neurological) 1st generation antipsychotics (chlorpromazine, thioridazine) side effects
sedation (histamine)
anticholinergic
orthostatic hypotension (alpha-1 blocker)
what drug is used to treat male pattern baldness
finasteride- can minimize progression if used early on
DHT is strongly correlated with follicular hair growth
what is used to treat ALOPECIA AREATA
autoimmune disorder that causes rapid-onset patch or diffuse hair loss
what does B anthraces look like on standard culture
forms long chains that are described as being “serpentine” or “medusa head”
nonhemolyzing adherence colonies
intracellular polyphosphate granules are characteristic of what bacteria and can be seen on what type of agar
Corynebacterium diphtheriae
can be visualized on microscopy after growth on LOEFFLER MEDIUM and staining with methylene blue
what are peritrichous flagella
flagella distributed uniformity over the entire surface of a bacterial cell and are characteristic of highly motile organisms like PROTEUS MIRABILIS
how are the oligodendrocytes in MS destroyed
Helper T cells abnormally react to antigens in the myelin, causing relate of inflammatory cytokine (IFN-gamma) that promote the infiltration of destructive macrophages/migroglia and leukocytes
slowed nerve conduction due to loss of myelin
what contributes to the blood-brain barrier
astrocytes (glial cells- non neural cells)
potassium buffering, neurotransmitter metabolism, and glial scar formation
what are microglia
resident macrophages in CNS
at what level do the renal arteries originate from the aorta
L1
where and from what is the IVC formed
L4-L5
right and left common iliac veins
drains to right atrium t T8
what is a test of a patients concentration
reciting months of the year backwards
what is a test of patients comprehension
following multistep commands
what is a test of short-term memory
recalling 3 unrelated words after 5 minutes
what is a test of executive function
drawing a clock oriented to the time requested
in order to make a diagnosis of DEMENTIA the patient must demonstrate
IMPAIRMENT ACROSS SEVERAL COGNITIVE DOMAINS during testing as well as FUNCTIONAL IMPAIRMENT in ACTIVITIES of DAILY LIVING
what are the most common causes of drug-induced tubular necrosis
aminoglycosides radiocontrast media cisplatin amphoteriin B foscarnet
ACE inhibitors can precipitate acute renal failure, causing what to happen to filtration fraction
decreases
see an increase of creatine of more than 30% (block the angiotensin mediated vasoconstriction of the efferent arteriole)
what findings at autopsy are characteristic of CARCINOID HEART DISEASE
endocardial thickening
fibrosis of tricuspid and pulmonary valves
PATHOGNUMONIC plaque-like DEPOSITS OF FIBROUS TISSUE occur most commonly on the ENDOCARDIUm leading to TRICUSPID REGURGITATION, pulmonic valvulopathy, and right-sided heart failure
what is the most common outcome of HBV
acute hepatitis with mild or subclinical symptoms that eventually completely resolve
