Blocks 35, 36 Flashcards Preview

UWORLD STEP 1 > Blocks 35, 36 > Flashcards

Flashcards in Blocks 35, 36 Deck (66):

Patient presents with numbness and tingling of hands and feet. Currently being treated for TB with Isoniazid and Rifampin. What is causing the sensory ataxia and decreased pain sensation?

Vitamin deficiency

Isoniazid is structurally similar to pyridoxine (B6) --> Increased urinary excretion of pyridoxine leading to a deficiency. 

Always give B6 with INH


Newborn with slanted palpebral fissures, epicanthal folds, thick nuchal folds, and a single palmar crease has a large, reducible midline abdominal protrusion covered by skin that is more pronounced when he cries. Umbilical stump is at the center of the protrusion. What is the cause of the protrustion?

Pt. has Down syndrome and an umbilical hernia caused by incomplete closure of the umbilical ring.


Pt with recurrent N. Gonorrhea infections. Why does treatment with Ceftriaxone and Azith not help the recurrence of the infection?

N. Gonorrhea can modify their outer membrane proteins via antigenic variation. Therefore, antibodies generated during one infection will only be specific for that single antigenic epitope. 

Repeated N. Gonorrhea infections could also be caused by complement deficiency (C5-C9) --> inability to form the MAC


Child with CF has deficient fat soluble vitamins (DAKE). What does a lack of vitamin A specifically cause in these patients?

Squamous metaplasia of epithelia to keratinizing epithelium. Vit A maintains orderly differentiation of specialized epithelia, including the mucus secreting columnar epithelia of the ocular conjunctiva, respiratory and urinary tracts, and pancreatic and other exocrine ducts.


What is effect modification?

When the effect of an exposure on an outcome is modified by another variable.


MOA of Thiazolidinediones (TZDs)

TZDs bind to peroxisome proliferator-activated receptor gamme (PPAR gamma) causing it to form a heterodimer complex with the retinoid X receptor. This complex then binds to transcriptional regulatory sequences of various genes responsible to glucose and lipid metabolism (altering their expression)


Pt. with a small perforation in the tympanic membrane and a pearly mass behind the membrane. Conduction hearing loss.

Cholesteatoma - a collection of squamous cell debris that form a mass behind the tympanic membrane. They can cause hearing loss due to erosion into auditory ossicles.


How is coronary dominance determined?

By the coronary artery that supplies blood to the posterior descending artery (PDA).

From the Right coronary artery (70% of people; right dominant heart)

From the Left circumflex artery (10% of people; left dominant heart)


What artery supplies the AV node?

AV nodal artery, which most often arises from the dominant coronary artery:

Left dominant = left circumflex

Right dominant = right coronary


Where is the AV node located in the heart?

On the endocardial surface of the right atrium, near the insertion of the septal leaflet of the tricuspid valve and the orifice of the coronary sinus


HPV infects what type of epithelium? Where is it found?

It has a predilection for stratified squamous epithelium.

Anal canal, vagina, cervix, true vocal cords


Where does complement bind on immunoglobin? (IgG and IgM)

In the Fc portion close to the hinge region


How is ventilation, perfusion, and therefore V/Q different from apex to base in the lung?

Perfusion greatly increases at base.

Ventilation increases slightly at base.

V/Q is decreased at the base bc Q increases more than V.


Theophylline overdose causes what symptoms?


Abdominal pain





Treat: activated charcoal to reduce GI absorption, beta blockers for tachyarrythmia


Von-Hippel Lindau (VHL) disease


Deletion of VHL tumor suppressor gene on Chrom 3p

Cerebellar hemangioblastomas, clear cell renal carcinomas, pheochromocytomas


SLE is associated with autoantibodies against snRNPs (anti-smith)... what is the effect?

snRNPs are an essential component of spliceosomes, which remove introns from pre-mRNA to form mature mRNA


Cystinuria pathogenesis


Defective transportation of cystine, ornithine, arginine, and lysine (COLA) across the intestinal and renal tubular epithelium. Recurrent nephrolithiasis. Urinalysis = hexagonal cystine crystals


Rounded and polygonal cells with abundant clear cytoplasm = classic histological description of what?

Clear cell carcinoma (renal) -- most common subtype of renal cell carcinoma


Pt. with disorganized speech (loosening of associations, nonsensical words), grossly disorganized behavior (unpredictable agitation, bizarre behaviors, inappropriate affect), functional decline, potentially with delusions, hallucinations, and negative symptoms (asociality, alogia (poverty of speech), affect flattening)  = classic presentation of what?


At least 2 symptoms

1 MUST be delusions, hallucinations, or disorganized speech

Present for over 1 month during a period of over 6 months, with prodromal or residual symptoms occurring the rest of the time


Alveolar hyperventilation 

Acute onset dyspnea, hypoxemia (low PaO2), and hypocapnia (PaCO2 below normal range)


Treatment for Psoriasis

Topical Vitamin D analogs (calcipotriene, calcitriol, tacalcitol) bind to the vit D receptor and inhibit keratinocyte proliferation and stimulate keratinocyte differentiation


Progressively weakening diaphragmatic contractions during maximal voluntary ventilation with intact phrenic nerve stimulation indicates what issue?

Neuromuscular junction pathology (MG)

or abnormally rapid diaphragmatic muscle fatigue (restrictive lung or chest wall disease)


In a patient with hypertension but with slow HR and long PR interval, what drugs could be used to treat the HTN without further affecting the heart?






MOA of Colchicine

Inhibits leukocyte migration and phagocytosis by blocking tubulin polymerization


Used for acute gouty arthritis in patients who cannot take NSAIDs


Axillary nerve injury looks like what

Sensory loss over lateral shoulder

Weakness on shoulder abduction

Denervation of deltoid muscle


*usually in the setting of shoulder trauma (anterior dislocation or humeral fracture)


Why is lung infartion a rare complication of PE?

Collateral blood flow supplied by the pulmonary and bronchial arteries


The presence of erythroid precursor cells in the liver and spleen is indivative of what?

Extramedullary hematopoiesis

(most frequently caused by severe chronic hemolytic anemias, like beta thalassemia)


Spontaneous deep intracerebral hemorrhage is most often caused by what?

Hypertensive vasculopathy

Chronic HTN leads to formation of Charcot-Bouchard aneuryms which my ultimately rupture and bleed within the deep brain structures. They're most frequently in the basal ganglia (putamen), cerebellar nuclei, thalamus, and pons. 


*basal ganglia blood supply = lenticulostriate arteries, which are small vessels off the MCA


Erythema multiforme = target lesions. Most frequently associated with what type of infection?



Rapidly profressive dementia and myoclonic jerks. Multiple vacuoles in gray matter.

Creutzfeldt-Jakob disease




Development of respiratory distress, diffuse neurological impairment, and an upper body petechial rash within days of severe long bone fracture = what?

Fat embolism syndrome


Young child with failure to thrive, recurrent ear infections coarse facial features, corneal clouding, hepatosplenomegaly, and restricted joint mobility

Inclusion cell (I-cell) disease

AR lysosomal storage disease

Lack of mannose 6 phosphate tagging of proteins needed to be sent to lysosomes


Postmenopausal woman with irregular vaginal bleeding, thickened endometrium and a solid left adenexal mass. Biopsy = yellow and firm, small cuboidal cells in sheets with gland-like structures containing acidophilic material arranged in a microfollicular pattern around a pink, eosinophilic center.

Granulosa cell tumors (sex cord stromal tumors)

Call exner bodies


How can you prevent neonatal tetanus?

Hygienic delivery

Umbilical cord care

Universale immunization of women who are pregnant or may become pregnant (moms provide passive immunity via transplacental IgG, protecting the baby until they can get vaccinated at 2 months old)


Arterial puncture above the inguinal ligament increases the risk of hemorrhage into what area?

Retroperitoneal space


What gives a bruise (hematoma) color?

Purple/blue intially = hemoglobin containing erythrocytes

Green = biliverdin from conversion of heme to biliverdin by heme oxygenase

Yellow = bilirubin (biliverdin reductase)


Hyperacute transplant rejection

Organ becomes cyanotic and mottled after anastamosis of the donor and recipient blood vessels

Antibody mediated and complement mediated injury to the vascular endothelium with formation of extensive thromboses

PREFORMED IGG ANTIBODIES within the recipient directed against donor antigens


Stimulus control therapy (for insomnia)

Use bed only for sleep and sex

Go to bed only when sleepy

LEave bed when unable to sleep and go to another room

Fixed wake up time, including weekends


Stable angina

Fixed atherosclerotic plaque obstructing at least 75% of the lumen of a coronary artery


The absence of normal enteral stimulation in patients receiving total parenteral nutrition leads to what GI side effect?

Decreased CCK release, biliary stasis, and increased risk of gallstones


What type of monotherapy can induce mania in patients with unrecognized bipolar disorder?

Antidepressant monotherapy


Retinal artery occlusion presents as acute, painless, monocular vision loss and is likely a thromboembolic complication of atherosclerosis in what vessel?

Internal Carotid Artery --> ophthalmic artery --> retinal artery


Young boy with exercise intolerance who experiences fatigue, muscle pain, and cramps durning exercise as well as severe muscle stiffness following stenuous activity.


Lactate Dehydrogenase Deficiency: Glycolysis is inhibited in strenuously exercising muscle because the muscle cells cannot regenerate NAD+


A penetrating injury at the left sternal border in the 4th intercostal space would puncture what?

Right Ventricle (most of the heart's anterior surface)


Blotchy red muscle fibers that look like "red ragged fibers" are characteristic of what type of pathology?

Mitochondrial myopathies

*maternal inheritance*


Sudden onset tachypnea and chest pain in a hospitalized patient should raise suspicion for what?



Major risk factors for PE

Immobilization (causes venous stasis)

Recent surgery (inflammation induces a hypercoagulable state)


Thrombotic occlusion of the pulmonary circulation leads to increased blood flow to the remainder of the lung and causes what?

V/Q mismatch (ventilation/perfusion) --> ischemic injury will cause inflammation, leading to surfactant deficiency and atelectasis in the surrounding lung regions --> hypoxemia


Pt who is able to communicate meaningfully but speech is slow and consists of primarily nouns and verbs. Speech punctuated by pauses after each word as the pt attempts to verbalize the next. Difficulty writing and signing. Spoken language is understood and capable of following commands.

Broca aphasia (motor, nonfluent)

Caudal part of the inferior frontal gyrus of the dominant (usually left) hemisphere.

Can also have right hemiparesis of face and upper limb



Long term glucocorticoid therapy leads to what levels of CRH, ACTH, and Cortisol?

Acute adrenal insufficiency (adrenal crisis) due to suppression of the HPA axis.



Low cortisol that cannot rise in response to stressful situations (infections/surgery)


What is the most frequent CNS tumor in immunosuppressed patients?

Primary CNS Lymphoma

Associated with AIDS and EBV

CD20 and CD79a


Pt with fatigue, rash, flushing, and abdominal cramps. Rash is worse with scratching and there is diffuse itching after hot showers. Frequently dizzy and light-headed after prolonged standing and episodes of syncope while working in the hot sun. Skin biopsy shows large clusters of mast cells with KIT (CD 117)

Systemic Mastocytosis

Excessive histamine release from degranulation of mast cells.



Histamine GI effect

Induces gastric acid secretion by parietal cells in the stomach, which can lead to gastric ulceration


Painless sudden loss of vision in one eye in a pt. with CAD, A fib, and type 2 diabetes

Central Retinal Artery Occlusion

Cherry red macula (separate blood supply), Retinal whitening


Low serum levels of C1 esterase inhibitor is diagnostic of what?

Hereditary Angioedema


Active kallikrein and bradykinin levels are increased because normal C1 esterase inhibitor suppressed the activation of C1 complement component and therefore the rest of the complement pathway. It also inactivates kallikrein, which catalyzes the conversion of kininogen to bradykinin.



Episodes of painless, non pitting, well-circumscribed edema (usually face, neck, lips, and tongue)

Hereditary Angioedema


What drug is contraindicated in patients with Hereditary Angioedema?

ACE Inhibitors

(bc they can also cause angioedema due to also increasing bradykinin levels)


Bile Acid resins MOA 

Bind bile acids in the GI tract and inhibt enterohepatic circulation leading to diversion of hepatic cholesterol to synthesis of new bile acids, increasing the uptake of LDL from circulation and decreasing blood LDL levels.


*They also increase hepatic production of TGs and increase TG-heavy VLDL particles into the circulation leading to HIGH TGs


PCNs and Cephalosporins function by irreversibly binding to what?

PCN binding proteins like Transpeptidases


How does Strep Pneumo form resistance against PCN and cephalosporins?

A change in the structure of the PBPs that prevent drug binding.


What type of cell membrane receptors are ligand gated and control the flow of Na+, Ca2+ INFLUX and K+ OUTFLUX?

Nicotinic cholinergic receptors


Young boy with blood that looks milky and forms a creamy-appearing supernatant upon standing. Plasma lipoprotein lipase activity after intravenous heparin is low. What disorder does he have?

Familial Chylomicronemia Syndrome (Type 1)

Manifestations: acute pancreatitis, eruptive skin xanthomas, hepatosplenomegaly


34 y/o female with diplopia, clumsiness of her left hand and numbness of her right foot. Scattered, periventricular, plague lesions found on MRI. What does she have? What are the plaques made up of?

Multiple Sclerosis

Demyelination of axons in white matter with loss of myelin sheeths and depletion of oligodendocytes within plaque areas.



5 week old boy with CF has tonic-clonic movements of his left upper and lower extremity. Born at home. No meds and no vaccines. Right-sided intracranial hemorrhage. What is lacking in this patient?

Vitamin K deficiency

K is an essential fat soluble vitamin cofactor for gamma-glutamyl carboxylase, an enzyme that carboxylates coag factors 2, 7, 9, 10


Small fibrotic focus in the lower lobe of the right lung and a calcified lymph node in the right lung hilus

Ghon complex

Primary TB exposure


Isoniazid must be processed by what in order for the drug to be activated within bacteria?

Mycobacterial catalase peroxidase