Uworld 6 Flashcards
Benign prostatic hyperplasia leads to?
Leads to progressive bladder outlet obstruction. Over time, increased urinary pressures can cause hydronephrosis and renal parenchymal atrophy with scarring. This can progress to chronic kidney disease.
What are transverse tubules (T-tubules)?
Invaginations of the sarcolemma that transmit depolarization signals to the sarcoplasmic reticulum to trigger the release of calcium and induce muscle contraction.
The uniform distribution of T-tubules in striated muscle fibers ensures that each myofibril contracts at the same time, which is necessary for efficient contraction.
Hypertrophic cardiomyopathy is caused by?
Genetic mutations affecting structural proteins of cardiac sarcomeres (eg, beta myosin heavy chain, myosin-binding protein C) and is one of the most common causes of sudden cardiac death in young adults.
Congenital diaphragmatic hernia (herniation of abdominal contents into the thorax) causes?
Hypoplasia from compression of the lungs.
Neonates present with respiratory distress shortly after birth.
What is seen on histo for hypertrophic cardiomyopathy?
cardiomyocyte hypertrophy with haphazard cellular arrangement and interstitial fibrosis
What is seen on x-ray for congenital diaphragmatic hernia?
thoracic bowel loops; the distal end of a feeding tube may also be seen within the thorax
Long-standing rheumatoid arthritis can affect what?
Can affect the cervical spine, causing vertebral malalignment (subluxation) that can affect the atlantoaxial joint.
Extension of the neck during endotrachael intubation can worsen the subluxation, leading to acute compression of the spinal cord and/or vertebral arteries.
Which HIV drug is associated with HLA-B*57:01?
Abacavir
What is Rett syndrome?
a genetic disorder characterized by normal development until age 6-18 months, when regression of speech, loss of purposeful hand movements, development of sterotypical movements, and gait abnormalities occur.
Neutropathology shows arrested brain development rather than neurodegeneration.
Cholecystokinin (CCK) stimulates what?
The release of cholecystokinin from the duodenum and jejunum after exposure to fat and protein rich meals stimulates gallbladder contraction.
In patients with gallstones or biliary sludge, contraction can force the stones/sludge against the gallbladder outlet, causing temporary occlusion of outflow and increased intragallbladder pressure. This manifests as postprandial upper abdominal pain that waxes and wanes with CCK levels (biliary colic).
The gag reflex is mediated by?
afferents from glossopharyngeal nerve (CN IX) and efferents from the vagus nerve (CN X)
An absent gag reflex may indicate dysfunction of what?
Medulla oblongata.
Fat embolism syndrome should be suspected in what kind of patients?
Patient with severe long bone and/or pelvic fractures who develops acute-onset neurologic abnormalities, hypoxemia, and a petechial rash.
Occlusion of the pulmonary microvessels by fat globules is an early histo finding
What are symptoms of lead poisoning?
Lead poisoning in adults typically occurs through occupational exposure.
Symptoms: colicky abdominal pain, constipation, lead lines on the gum, peripheral neuropathy and amenia
What are labs for lead poisoning?
Microcytic anemia with normal iron studies and peripheral blood smear may reveal basophilic stippling
Ethanol inhibits what?
Inhibits gluconeogenesis and can cause hypoglycemia once hepatic glycogen stores are depleted.
Classic 21-hydroxylase deficiency causes?
decreased cortisol and aldosterone production with increased adrenal androgen production
Classic 21-hydroxylase deficiency causes what in boys?
presents 1-2 weeks after birth with vomiting, hypotension, hyponatremia, and hyperkalemia due to salt wasting; genitalia are normal
Classic 21-hydroxylase deficiency presents how in girls?
presents at birth with ambiguous genitalia
Traits of blastomyces dermatitdis
dimorphic fungus seen in tissue as round or oval yeasts with thick walls and broad based budding
Endemic in southeastern US (states east of Mississippi River)
Lungs are primary site of involvement, and the skin and bone are the major sites of dissemination
MOA of raltegravir
an integrase inhibitor that disrupts HIV genome integration, preventing synthesis of viral mRNA
What is necessary to induce viral HIV gene expression?
Integration of double-stranded HIV DNA into the host cell’s chromosomes is necessary to induce viral gene expression and prevent degradation of the viral genome.
Hypovolemia triggers a variety of compensatory mechanisms to improve tissue perfusion. These include:
-activation of the renin-angiotensin-aldosterone system (resulting in increased aldosterone and endothelin release)
-increased vasopressin release
-increased sympathetic tone
What are most common side effects of aspirin?
GI mucosal injury and bleeding.
These are due primarily to cyclooxygenase-1 inhibition, which results in impaired prostaglandin-dependent GI mucosal defense and decreased platelet aggregation.
What is bullous pemphigoid?
Autoimmune blistering disease that typically occurs in patients >60
It presents with tense bullae with rare mucosal involvement. Autoantibodies against hemidesmosomes create subepidermal cleavage.
What is seen on immunofluorescence for bullous pemphigoid?
liner deposition of IgG and/or C3 along the basement membrane
Intracranial pressure can be temporarily reduced with what?
intravenous mannitol, an osmotically active agent that increases plasma oncotic pressure, causing water from the interstitial space to be drawn into the vascular compartment.
In some patients (eg, history of heart failure, low left ventricular reserve function), rapidly increased intravascular volume can cause pulmonary edema by abruptly increasing pulmonary capillary hydrostatic pressure.
What are chromaffin cells?
Modified neuroendocrine cells derived from the neural crest
Chromaffin cells in the adrenal medulla are stimulated by?
Acetylcholine released by sympathetic preganglionic neurons and secrete catecholamines directly into the bloodstream to amplify sympathetic nervous system activity
Communicating hydroceles and indirect inguinal hernias are caused by?
An incomplete obliteration of the processus vaginalis.
The resultant connection between the scrotum and abdominal cavity can allow for fluid leakage (hydrocele) or the passage of abdominal contents (indirect inguinal hernia)
What is heard on ausculation for aortic regurgitation?
High pitched, diastolic murmur with a decrescendo intensity pattern
Where is the murmur of aortic regurgitation due to aortic root dilation best heard at?
At the right upper sternal border
Where is the murmur of aortic regurgitation due to valvular pathology best heard at?
At the 3rd intercostal space
How is a premature ventricular contraction seen on ECG?
wide QRS complex, opposite-facing T wave, and brief ensuing sinus pause
Left ventricular filling is less than normal at the time of the PVC
The ensuring sinus pause allows for greater than normal filling during the post-PVC beat
What is the most common primary immune deficiency?
Selective IgA deficiency
How does selective IgA def present?
Recurrent sinopulmonary and gastrointestinal infections as well as autoimmune disease
Patients with severe IgA def can have anaphylaxis during transfusion of blood products that contain small amounts of IgA
What is seen in Kawasaki disease?
Vasculitis characterized by fever for >5 days and >4 of the following: nonexudative conjunctivitis, extremity changes, cervical lymphadenopathy, mucositis, and polymorphous rash
Alpha-1 antitrypsin def can cause?
Can induce early onset emphysema, which is further accelerated by smoking
What is emphysema?
Characterized by expiratory airflow obstruction (decreased FEV1/FVC ratio), airspace enlargement and hyperinflation (increased total lung capacity), and a decreased diffusing capacity due to loss of alveolar surface area
MOA of statins
Statins inhibit the intracellular rate-limiting step of cholesterol biosynthesis via competitive inhibition of HMG-CoA reductase.
This leads to enhanced hepatic LDL receptor recycling and increased LDL clearance from the circulation.