Uworld27 Flashcards
Function of parietal cells
Parietal cells release hydrogen ions into the gastric lumen by means of the H/K ATPase, which requires hydrolysis of ATP and is therefore an active transport mechanism.
Omeprazole and other proton pump inhibitors suppress the activity of the gastric parietal cell H/K ATPase leading to an increase in the pH of the gastric lumen.
To access the left side of the heart, cardiac venous catheters must cross?
the interatrial septum at the site of the foramen ovale.
Entry into the left atrium allows for direct measurement of left atrial pressure and for access to arrhythmogenic foci on the left atrial myocardium or pulmonary veins.
Neisseria can be isolated on which medium?
Neisseria can be isolated by culture on selective media such as the Thayer-Martin VCN (vancomycin/colistin/nystatin) medium, which inhibits growth of contaminants such as gram+ organisms, gram negative organisms other than Neisseria, and fungi.
What is septic shock?
Septic shock is a dysfunctional host response to an infectious pathogen resulting from massive upregulation of vasodilators.
A vasopressin deficit contributes to unbalanced vasodilation and refractory hypotension.
Hepatic A virus infection is characterized by?
Hepatitis A virus infection is most commonly silent or subclinical (“anicteric”) in young children but can also present as an acute, self limited illness characterized by jaundice, malaise, fatigue, anorexia, nausea, vomiting, RUQ pain, or an aversion to smoking.
What is a migraine?
an episodic neurologic disorder that results in severe, unilateral, throbbing headaches that are often associated with photophobia, phonophobia, and nausea/vomiting.
Migraine attacks typically last 4-72 hours, and up to 25% of patients also develop an aura (focal, reversible neurologic symptoms that precede or accompany the headache)
What is infantile hemangiomas?
benign vascular tumors composed of proliferating endothelial cells that most frequently affect the head or neck region.
Natural history of these lesions involve rapid growth of a red, cutaneous plaque followed by spontaneous regression.
What is schizophrenia?
diagnosed in patients with signs of disturbance for >6 months, including at least 1 month of >2 of the following active symptoms (with at least 1 from the first 3): delusions, hallucinations, disorganized speech, disorganized/catatonic behavior, and negative symptoms.
Treatment of acromegaly
Acromegaly is usually treated with resection of the somatotroph pituitary adenoma, but additional medical therapy is needed for patients with residual tumor.
Octreotide is a long acting somatostatin analogue that inhibits growth hormone secretion and subsequently insulin-like growth factor-1 release. It also reduces residual adenoma size in many patients.
What is the most common etiology of mesial temporal lobe epilepsy?
Recurrent focal impaired awareness seizures that are preceded by a distinctive aura (eg, uneasy epigastric sensation, olfactory hallucinations) are characteristic of mesial temporal lobe epilepsy.
The most common etiology is hippocampal sclerosis (mesial temporal sclerosis), which is associated with childhood febrile seizures.
Formula for absolute risk reduction
Absolute risk reduction = event rate in the control group - event rate in the treatment group
MOA of aromatase inhibitors (anastrozole, letrozole, exemestane)
Estrogen is the main hormone responsible for the growth and development of estrogen receptor-positive breast tumors.
Aromatase inhibitors decrease the synthesis of estrogen from androgens, suppressing estrogen levels and slowing progression of ER+ tumors.
t-test is used to compare?
the difference between the means of 2 groups.
Analysis of variance (ANOVA) compares?
the difference between the means of 2 or more groups.
What is McCune-Albright syndrome?
characterized by the triad of fibrous dysplasia of the bone, endocrine abnormalities, and cafe-au-lait spots.
The condition results from an activating mutation in the G protein/cAMP/adenylate cyclase signaling pathway.
What is acute respiratory distress syndrome?
characterized by hypoxia and bilateral pulmonary infiltrates and is associated with pneumonia, sepsis, trauma, and pancreatitis.
The associated pulmonary edema is noncardiogenic in nature, so the pulmonary capillary wedge pressure will be within the normal range (6-12 mmHg)
What is the mutations seen in adenocarcinoma of the lung?
the most common primary lung cancer in the general population, women, and nonsmokers.
Epidermal growth factor receptor (EGFR) mutations and ALK gene rearrangments are seen more commonly in nonsmokers and thought to contribute to disease formation in this subgroup.
Adenocarcinoma is typically located peripherally and may be associated with clubbing or hypertrophic osteoathropathy.
What is occupational asthma?
involves airway inflammation and bronchoconstriction triggered by sensitization to a workplace aeroallergen (eg, isocyanates, grain proteins).
Improvement on sustained absence from work (eg, vacation) is an important clinical clue.
Normal spirometry does not exclude asthma because bronchospasm may occur intermittently.
What is linkage disequilibrium?
Two allele loci are said to be in linkage disequilibrium when a pair of alleles are inherited together in the same gamete (haplotype) more often or less often than would be expected given random pairing.
This most often occurs when the genes are in close physical proximity on the same chromosome.
What is acute interstitial nephritis?
a common cause of renal dysfunction; up to 75% of cases are due to medications including nonsteroidal anti-inflammatory drugs, antibiotics, diuretics, and proton pump inhibitors.
Presenting features include fever, rash, and eosinophilia.
UA: pyuria and WBC casts with elevated urine eosinophils.
What is sarcoidosis?
an inflammatory disorder characterized histologically by noncaseating granulomas consisting of aggregates of epithelioid macrophages and multinucleated giant cells.
Common manifestations include hilar adenopathy, pulmonary infiltrates, skin rash, ophthalmic findings, and constitutional symptoms.
What is recall bias?
results from study participants’ inaccurate recall of past exposure and occurs most often in retrospective studies such as case-control studies.
People who have experienced an adverse effect are more likely to recall risk factors than those who have not experienced an adverse event.
Hyperprolactinemia suppresses secretion of?
GnRH, which leads to reduced estrogen in women. Low estrogen levels are a risk factor for accelerated bone loss.
What is pseudocholinesterase deficiency?
Succinylcholine, a depolarizing neuromuscular blocking agent, is rapidly hydrolyzed by plasma pseudocholinesterase.
Patients with pseudocholinesterase deficiency have prolonged neuromuscular paralysis after drug adminstration.
What is HIV-associated dementia?
HIV-associated dementia should be suspected in patients with AIDS who have progressive cognitive decline.
The characteristic histopathologic finding is microglial nodules (groups of activated microglia/macrophages around small areas of necrosis) and multinucleated giant cells.
What is injured in a supracondylar humeral fracture?
Supracondylar humeral fractures commonly occur after hyperextension of the elbow as a result of a fall onto an outstretched arm.
The median nerve and brachial artery run along the anteromedial aspect of the elbow and are the structures most likely to be injured with anteromedial displacement of the proximal fracture fragment.
Carotid sinus massage leads to?
an increase in parasympathetic tone causing temporary inhibition of sinoatrial node activity, slowing of conduction through the atrioventricular node, and prolongation of the AV node refractory period.
It is a useful vagal maneuver for termination of paroxysmal supraventricular tachycardia.
What causes head lice?
Pediculus human capitis (ie, head lice) infestation is common in school children and adults who come into close contact with infested individuals.
Transmission is usually by direct contact.
The eggs (nits) are attached to the hair shaft and can be identified on inspection.
First line treatment includes topical pediculicides (eg, permethrin, ivermectin)
MOA of bile acid-binding resins (eg, cholestyramine, colestipol, colesevelam)
inhibit the enterohepatic circulation of bile acids. This leads to diversion of hepatic cholesterol to synthesis of new bile acids, increased uptake of cholesterol from the circulation, and reduced blood LDL levels.
However, bile acid binding resins increase hepatic production of triglycerides and can cause hypertriglyceridemia.
What is mitral stenosis?
opening snap followed by a rumbling diastolic murmur that is best heard over the cardiac apex.
On the left ventricular pressure-volume loop, the opening snap occurs during mitral valve opening at the end of isovolumetric relaxation, and it is followed by a diastolic rumble during diastolic filling.
What is selection bias?
In prospective studies, disproportionate loss to follow up between the exposed and unexposed groups creates the potential for attrition bias, which is a form of selection bias.
As a result, investigators generally try to achieve high patient follow-up rates in prospective studies.
What is the Golgi tendon system?
The muscle spindle system is a feedback system that monitors and maintains muscle length, while the Golgi tendon system is a feedback system that monitors and maintains muscle force.
Golgi tendon organs are exquisitely sensitive to increases in muscle tension but are relatively insensitive to passive stretch.
The internal larygneal nerve mediates?
the afferent limb of the cough reflex above the vocal cords.
Foreign bodies (eg, fish bones) can become lodged in the piriform recess and may cause damage to the nerve, impairing the cough reflex.
In chronic kidney disease, reduced excretion of phosphate can cause hyperphosphatemia. This induces?
hypocalcemia directly by binding free calcium and depositing in tissues, and indirectly by triggering fibroblast growth factor 23 secretion (decreases calcitriol production and intestinal calcium absorption).
The resulting hypocalcemia can manifest as neuromuscular excitability (eg, carpal spasm)
MOA of topical capsaicin
causes defunctionalization of afferent pain fibers and depletion of substance P.
Initial application results in a burning stinging sensation, but chronic exposure leads to reduced pain transmission.
What is Pott disease?
Mycobacterium tuberculosis spondylitis (Pott disease) is usually the result of hematogenous seeding of vertebrae from primary pulmonary infection.
Manifestations typically arise months or years later (due to reactivation) and include chronic, progressive back pain, fever, and radiographic evidence of vertebral bone destruction and fluid collection.
What are the most common adverse effects of psychostimulant meds used to treat attention-deficit hyperactivity disorder?
decreased appetite and insomnia. They are usually mild and can be managed without stopping the medication.
What is hirschsprung disease?
a congenital disorder caused by failure of normal craniocaudal migration of neural crest cells during embryogenesis.
The affected colon segment (eg, rectosigmoid) lacks ganglionic innervation and is unable to relax, resulting in obstruction with failure to pass meconium and bilious emesis.
Forceful expulsion of gas and stool on rectal exam is typical.
Acetylcholine release from presynaptic terminal vesicles at the neuromuscular junction depends upon?
the influx of extracellular calcium into the presynaptic terminal.
Calcium influx into the nerve terminal occurs following neuronal depolarization and opening of voltage gated calcium channels.
What is septic abortion?
Symptoms of septic abortion typically include fever, abdominal pain, uterine tenderness, and/or malodorous discharge after pregnancy termination.
Common pathogens include Enterobacteriaceae, group A strep, and Staph aureus.
Treatment: urgent surgical evacuation and broad spectrum antibiotics.
