Uworld12 Flashcards
What is Brown-Sequard syndrome?
Results from hemisection of the spinal cord.
It is characterized by ipsilateral paralysis due to corticospinal tract injury, ipsilateral loss of vibratory, proprioceptive, and light touch sensation (dorsal columns); and contralateral loss of pain, temp, crude touch sensation (spinothalamic tract) below the level of injury
What is achalasia?
is caused by reduced numbers of inhibitory ganglion cells in the esophageal wall.
Esophageal manometry in achalasia shows decreased amplitude of peristalsis in the mid esophagus, with increased tone and incomplete relaxation at the lower esophageal sphincter
MOA of calcineurin inhibitors (pimecrolimus, tacrolimus)
works by inhibiting T cell signaling needed to transcribe the proinflammatory cytokine IL-2, thereby decreasing inflammation
What is used for the treatment of atopic dermatitis?
Atopic dermatitis is an inflammatory condition that can be treated with calcineurin inhibitors (pimecrolimus, tacrolimus) as second line therapy after topical corticosteroids.
Role of vitamin K
Vitamin K is a cofactor for gamma-glutamyl carboxylase, an enzyme that activates coagulation factors II, VII, IX, and X via posttranslational gamma carboxylation.
Intestinal diseases a/w malabsorption (eg, inflammatory bowel disease) are a risk factor for vitamin K def, which typically presents with mucosal bleeding, bruising, and prolonged PT and PTT (if severe)
Most oropharyngeal carcinomas (eg tonsil, base of tongue) are caused by?
HPV infection.
HPV 16 and 18 are particularly likely to cause malignant transformation.
What is hypertrophic cardiomyopathy?
HCM typically involves interventricular septal hypertrophy that obstructs left ventricular outflow and creates a systolic murmur that decreases in intensity with maneuvers that increase LV blood volume (eg handgrip, passive leg elevation)
Characterized by increased LV muscle mass with a small LV cavity, preserved ejection fraction, and impaired relaxation leading to diastolic dysfunction
Where does isotype switching occur?
The primary immune response to a new antigen initially results in plasma cells that produce only IgM.
Isotype switching occurs later in germinal centers and gives B cells the ability to produce antibodies of differing isotypes (IgG, IgA)
Treatment of gonorrhea with coinfection chlamydia
Infectious urethritis in men is typically caused by Neisseria gonorrhoae, Chlamydia trachomatis, or mycoplasma genitalium.
Diagnosis is generally made by nucleic acid amplification testing, but microscopy with Gram stain can be used to quickly diagnose gonoccoccal infection.
Patients with gonorrhea and positive or uncertain chlmaydia: ceftriaxone and doxycycline; ceftriaxone alone can be used in those who do not have chlamydia coinfection
What are symptoms of schizophernia?
Positive psychotic symptoms: delusions, hallucinations, disorganization
Negative: flat affect (lack of facial expression)
Negative symptoms typically persist between acute psychotic episodes and are more resistant to treatment.
Vasopressin and oxytocin are synthesized where?
Vasopressin and oxytocin are synthesized and packaged with carrier proteins (neurophysins) within neurons found in the hypothalamus.
The hormones are then transported down axonal projections to the posterior pituitary (neurohypophysis), where they are secreted into circulation.
What is a fatty streak?
Fatty streaks are the earliest lesions of atherosclerosis and can be seen as early as the second decade of life.
They appear as a collection of lipid-laden macrophages (foam cells) in the intima that can eventually progress to atherosclerotic plaques.
What happens to the body after giving intravenous fluids?
IV fluids increase the intravascular and left ventricular end-diastolic volumes.
The increase in preload stretches the myocardium and increases the end-diastolic sarcomere length, leading to an increase in stroke volume and cardiac output by the Frank-Starling mechanism
What is seen in lateral medullary infarct (wallenberg syndrome)?
-Vertigo (vestibular nucleus)
-loss of pain/temp sensation on the ipsilateral face (trigeminal nucleus)
-contralateral body (spinothalamic tract)
-bulbar weakness (lower cranial nerves)
-ipsilateral horner syndrome (descending sympathetic nervous system fibers)
What does haemophilus influenza require to grow?
Haemophilus influenza is a G- coccobacillus that requires both X factor (hematin) and V factor (NAD+) to grow.
H Influenzae type b has an antiphagocytic polysaccharide capsule, which allows it to spread hematogenously and cause invasive disease such as septic arthritis and meningitis.
Multiple sclerosis effect on the bladder
Patients with multiple sclerosis often develop a spastic bladder a few weeks after developing an acute lesion of the spinal cord.
These patients present clinically with increased urinary frequency and urge incontinence
Urodynamic studies show the presence of bladder hypertonia.
Acute salicylate toxicity causes?
a primary respiratory alkalosis and a primary metabolic acidosis with an anion gap due to increased lactate production.
Symptoms: tinnitus, tachypnea, hyperthermia, vomiting, and altered mental status.
Large pituitary adenomas can cause?
bitemporal hemianopnia due to compression of the optic chiasm
The most common hormonally active pituitary tumors are?
Prolactinomas; can cause severe hyperprolactineia.
Moderate hyperprolactinemia can also occur in nonprolactinoma tumors because prolactin secretion is under negative regulation by dopamine from the hypothalamus
MOA of mannitol
mannitol increases plasma osmolality, leading to the flow of water down its concentration gradient from the intracellular space to the plasma, helping to reduce intracranial pressure.
The resulting plasma expansion also reduces serum sodium levels and increases glomerular filtration/tubular flow.
Mannitol is freely filtered and not reabsorbed by the renal tubules, resulting in a hyperosmolar glomerular filtrate
What is responsible for wound reepithelization?
Keratinocytes; they migrate into the wound from its edges and are repopulated by replication within the stratum basale.
Keratinocytes continue to migrate and proliferate until they contact other similar cells, a regulatory mechanism known as contact inhibition
What is acute pituitary hemorrhage (pituitary apoplexy)?
severe headache, bitemporal hemianopsia (compression of the optic chasm), and opthalmoplegia (compression of the oculomotor nerve CNIII)
It usually occurs in a preexisting pituitary adenoma.
Pituitary apoplexy is a medical emergency that requires urgent treatment with glucocorticoids to prevent acute adrenal crisis and circulatory collapse.
How does a pericardial effusion present?
Acute viral pericarditis is commonly complicated by pericardial effusion.
Classic features of pericardial effusion include tachycardia and ECG: low voltage QRS and electrical alternans.
CXR: enlarged cardiac silhouette with clear lungs
Abruptio placentae is caused by?
rupture of maternal vessels at the uteroplacental interface that leads to premature separation of the placenta from the myometrium
Patients typically have painful vaginal bleeding and a tender, firm uterus
Preeclampsia increases the risk of abruptio placentae.
How does congenital hydrocephalus present
Often presents with macrocephaly and poor feeding.
Imaging showing enlarged ventricles are diagnostic.
Untreated hydrocephalus leads to developmental delays, poor growth and muscle spasticity (due to stretching of the periventricular pyramidal tracts)
MOA of loperamide
an opioid agonist that exerts its antidiarrheal effects by binding to mu opiate receptors in the colonic myenteric plexus, which inhibits acetylcholine release, decreases intestinal smooth muscle activity, and slows peristalsis.
It undergoes high first pass metabolism and does not cross the blood brain barrier, thus avoiding systemic opiate related adverse effects (sedations, respiratory depression)
What is dermatomyositis?
proximal muscle weakness resembling polymyositis, with additional inflammatory features affecting the skin (heliotrope rash, Gottron papules).
In both conditions, involvement of striated muscle in the oropharynx and heart can lead to dysphagia, pulmonary aspiration and myocarditis
When does primary spontaneous pneumothorax occur in patients without preexisting pulmonary disease?
when a large change in the alveolar or intrapleural pressure results in a break in the visceral (eg, ruptured superficial bleb) pleura and air trapping between the pleural spaces.
Tracheoesophageal fistula with esophageal atresia results from?
failure of the primitive foregut to approximately divide into separate trachea and esophageal strictures.
Infants present shortly after birth with excessive secretions and choking/cyanosis during feeds.
What are the physiologic changes in the respiratory system that occur with exercise?
-increased minute ventilation (via both an increase in respiratory rate and tidal volume)
-reduced physiologic dead space
-increased ventilation-perfusion ration
-increased extraction of oxygen by skeletal muscle (resulting in decreased mixed venous oxygen content).
What organisms are causes of infection with deficient MAC complex?
deficiency of the complement factors that form the membrane attack complex (C5-C9) results in recurrent infections of the lung and meninges by encapsulated bacteria (eg, Strep pneumo, Neisseria meningitdis)
Treatment for acetaminophen overdose?
Acetaminophen overdose overwhelms normal metabolic pathways in the liver and depletes intrahepatic glutathione stores, leading to excessive production of N-acetly-p-benzoquinone imini (NAPQI), a toxic metabolite.
Management: N-acetylcysteine, which increases intrahepatic glutathione stores and facilitates NAPQI detoxification
What is mosaicism?
presence of multiple, genetically different cell lines within the body.
Can result from several processes, including chromosomal nondisjunction or a mutation during the first stages of embryonic development.
Somatic mosaicism results from a mixture of normal and mutated somatic cells, often leading to a milder form of the disease.
Radial nerve provides sensory innervation to?
The skin of the posterior arm, forearm, and dorsal lateral hand and provides motor innervation to all the extensor muscles of the upper limb below the shoulder.
Damage to the proximal radial nerve (at the axilla or mid shaft humerus) results in?
wrist drop
what is stress urinary incontinence?
involuntary urine leakage with increased intraabdominal pressure (eg, coughing, sneezing).
Pelvic floor muscle (Kegel) exercises target and strengthen the lavator ani muscle complex, improving support around the urethra and bladder and symptoms of stress urinary incontinence.
Patients with sickle cell trait have relative protection from?
Patients with sickle cell trait are typically asymptomatic and have relative protection from malaria caused by Plasmodium falciparum.
These patients usually have normal hemoglobin, reticulocyte, and red blood cell index values. Life expectancy is the same as that of the general population
Where does hydroxylation of proline and lysin residues in collagen occur in?
The hydroxylation of proline and lysine residues in collagen helps it attain its maximum tensile strength.
This process occurs in the rough endoplasmic reticulum and requires vitamin C as a cofactor.
Impaired collagen synthesis resulting in vitamin C def (scurvy) can lead to fragile vessels, predisposing to gingival bleeding, ecchymosis, and petechia
What can chemotherapy induced nausea and vomitting be treated with?
Chemotherapy induced nausea and vomitting is mediated by peripheral and central mechanisms.
It can be treated with serotonin receptor antagonists (eg, ondansetron) to prevent serotonin stimulation of afferent vagal fibers in the bowel wall (peripheral cause) and neurokinin-1 receptor antagonists (eg, aprepitant) to prevent the effects of substance P in the brainstem (central cause).
What is seen in Legionella pneumophilia infection?
typically marked by high fever and fatigue followed by significant gastrointestinal, pulmonary, constitutional symptoms.
The organism is not well visualized on Gram stain and does not grow on traditional culture media; L pneumophilia infection is primarily diagnosed by polymerase chain reaction or urine antigen testing
