Uworld10 Flashcards
Function of glucose-6-phosphate dehydrogenase
rate limiting enzyme in the pentose phosphate pathway, the major source of cellular NADPH
This molecule is necessary for reducing glutathione (protects RBCs from oxidative damage) and for the biosynthesis of cholesterol, fatty acids, and steriods.
What is reaction formation?
defense mechanism that involves replacing unacceptable feelings and impulses with their extreme opposites
In patients with cystic fibrosis, pathogenic bacteria colonize the respiratory tract early in the disease course. The leading pathogen in adults is?
Pseudomonas aeruginosa, which forms a thick biofilm to prevent its full elimination from the body.
Disrupted development of the first and second pharyngeal arches results in?
hypoplasia of the arches’ musculoskeletal derivatives, including the mandible, maxilla, zygomatic bones, and ossicles.
Patients taking daily maintenance nitrates need to have a nitrate free period every day to avoid?
tolerance to the drug
What is myasthenia gravis characterized by?
autoantibodies against postsynaptic nicotinic acetylcholine receptors at the neuromuscular junction, which result in receptor degradation.
Patients have extraocular, bulbar, and facial weakness that worsens with activity.
In severe cases, the respiratory muscles may be affected, leading to hypoventilation and respiratory failure.
MOA of enoxaparin
Low molecular weight heparin that functions like heparin in that it binds and activates antithrombin III.
Activated ATIII binds to factor Xa and stops factor Xa from converting prothrombin to thrombin. Due to its fewer numbers of molecules, LMWH acts primarily on factor Xa, not thrombin.
What is schizophreniform disorder?
Psychotic symptoms (delusions, hallucinations, disorganized speech and behavior, negative symptoms) lasting >1 month and <6 months
Where is the amino acid binding site on tRNA?
The 3’CCA tail of tRNA.
Aminoacyl tRNA synthetase is the enzyme responsible for “loading” the appropriate amino acid to the 3’ terminal hydroxyl group of the CCA tail
How does thiazide diuretics cause hypercalcemia?
Thiazide diuretics cause hypercalcemia by increasing the distal tubular reabsorption of Ca2+
The increased circulating calcium levels result in suppression of parathyroid hormone, which distinguishes this effect from hyperparathyroidism
Primary hyperaldosteronism results in?
hypertension and hypokalemia, which can cause muscle cramps, muscle weakness, and paresthesia
Graft versus host disease pathogenesis
graft versus host disease can occur following transplantation of organs rich in lymphocytes (eg liver)
T lymphocytes found in the donor organ become sensitized against the MHC antigens of the recipient and subsequently attack the host’s tissues.
skin, liver, and GI tract are most commonly affected
How does viridans streptococci cause subacute bacterial endocarditis
viridans strep produce dextrans that aid them in colonizing host surfaces, such as dental enamel and heart valves.
These organisms cause subacute bacterial endocarditis, classically in pts with preexisting cardiac valvular defects after dental work
in response to chronic hypoxemia (eg advanced chronic obstructive pulmonary disease), specialized peritubular fibroblasts in the renal cortex release?
erythropoietin: stimulates RBC production (ie, secondary polycythemia) by the bone marrow, improving the oxygen carrying capacity of the blood
Many pts with hypertrophic cardiomyopathy have exercise intolerance due to?
left ventricular outflow tract obstruction.
This outflow obstruction is worsened by decreased LV blood volume.
Beta blockers decrease heart rate and LV contractility to increase LV blood volume, reduce LV outflow tract obstruction, and improve symptoms
What is concentric hypertrophy
uniform thickening of the ventricular wall and narrowing of the ventricular cavity due to increased afterload (eg, chronic hypertension, aortic stenosis)
What is eccentric hypertrophy
reduced ventricular wall thickness with an associated increase in chamber size due to volume overload
The murmur of valvular aortic stenosis sounds like?
ejection or midsystolic murmur of crescendo-decrescendo with maximum intensity over the right second interspace and radiation to neck and carotid arteries
What is the most common cause of aortic stenosis in elderly patients (>70 yo)
degenerative calcification of the aortic valve leaflets
What is the relation of GFR and creatinine?
When the GFR is normal, relatively large decreases in GFR result in only small increases in serum creatinine.
When the GFR is significantly decreased, small decrements in GFR produce relatively large changes in serum creatinine.
rule: every time GFR halves, serum creatinine doubles
Injury to axillary nerve most commonly occurs?
in the setting of shoulder trauma (eg, anterior shoulder dislocation, surgical neck of the humerus fracture)
It presents with sensory loss over the lateral shoulder and weakness on shoulder abduction (due to denervation of deltoid)
What is the most common cause of acute bacterial prostatitis and other UTIs?
e. coli because of adhesins on its fimbriae that promote adherence to urothelial or mucosal cells
What is acute bacterial prostatitis usually caused by?
reflux of urine and organisms from the bladder and urethra.
The risk is greater in patients with anatomic abnormalitites (eg, strictures) or bladder catheterization.
What is disseminated intravascular coagulation?
Widespread activation of the coagulation cascade, leading to excessive thrombin production and formation of micro thrombi.
Subsequent conversion of plasminogen to plasmin results in increased fibrinolyis to clear the thrombi.
What are the labs for DIC?
Labs will show a consumption of clotting factors (prolonged PT/PTT) and platelets (thrombocytopenia) and signs of excessive fibrinolysis (elevated D-dimer)
Ethylene glycol and methanol are toxic alcohols that cause?
anion gap metabolic acidosis and elevated osmolar gap.
Toxicity occurs after metabolization by alcohol dehydrogenase; fomepizole is a competitive inhibitor of alcohol dehydrogenase and is used for the treatment of acute poisoning.
Adhesion of cells to the extracellular matrix involves integrin-mediated binding to?
fibronectin, collagen, and laminin.
What is diabetic ketoacidosis?
Polydipsia, polyuria, and a fruity odor to the breath or urine.
Associated with elevated anion gap metabolic acidosis that is usually with compensatory resp alkalosis. = yields a low pH, low serum bicarbonate, and low PaCO2
How is a Zenker diverticulum caused?
Diminished relaxation of cricopharyngeal muscles during swallowing results in increased intraluminal pressure in the oropharynx. This may cause the mucosa to herniate through a zone of muscle weakness in the posterior hypopharynx, forming a Zenker (false) diverticulum, which presents in elderly with oropharyngeal dysphagia, halitosis, regurgitation, and recurrent aspiration
What is the risk factors for atrial fibrillation?
Age, independent of comorbidities, is one of the strongest risk factors for atrial fibrillation as age related change to the atrial myocardium is one of the primary contributors to atrial remodeling.
Left atrial dilation is the other primary contributor to atrial remodeling; therefore comorbidities that cause left atrial dilation (HTN, heart failure, mitral valve disease) are also associated with atrial fibrillation.
How does human herpesvirus 6 infection (roseola) present?
fever for 3-5 days followed by a trunal rash. It is also the most common cause of febrile seizures.
Proto-oncogenes stimulate cell proliferation, and their over expression leads to increased cellular proliferation and neoplastic growth. List an example
KRAS is a proto oncogene often activated in tumor cells
Anti-oncogenes are tumor suppressors as they inhibit cellular proliferation. Loss of function mutation leads to tumor development. Name some examples
APC, BRCA1, TP53, RB
Isosorbide dinitrate has a low bioavailability due to?
extensive first pass hepatic metabolism prior to release in the systemic circulation.
Sublingual nitroglycerin is absorbed directly from oral mucosa into the venous circulation and has a higher bioavailibilty
What are symptoms of tricyclic antidepressant overdose?
seizures, anticholinergic toxicity, hypotension, and cardiac toxicity (QRS widening, ventricular arrhythmias)
What helps you find the appedix?
The teniae coli are 3 separate smooth muscle ribbons that travel longitudinally on the outside of the colon and converge at the root of the vermiform appedix.
How does crohn disease present?
prolonges diarrhea and abdominal pain. Low grade fever, fatigue, malabsorption, and weight loss are also common.
Transmural inflammation of the bowel wall may result in the formation of fistulas, abscesses, and fibrotic strictures
Gastric acid is neutralized by?
By bicarbonate from the submucosal (Brunner) glands of the duodenum and from pancreatic duct secretions.
Chronic overproduction of gastric acid can lead to hyperplasia of the submucosal glands
What are markers of osteoblast activity?
Bone-specific alkaline phosphatase levels correlate with osteoblast activity.
Other markers: N-terminal propeptide of type 1 procollagen, which is released during post-translation cleavage of type 1 procollagen.
Where does the anterior pituitary forms from?
surface ectoderm
