A 47-year-old undergoes surgery and receives a medication that blocks nicotinic receptors at autonomic ganglia. Shortly after, she develops orthostatic hypotension and decreased GI motility. The team reviews which neurotransmitter is released by all preganglionic autonomic neurons (both sympathetic and parasympathetic) at the ganglion. Which neurotransmitter is used by all preganglionic ANS neurons?
Read DetailsA term newborn of a mother who received routine prenatal care has no signs of infection. The parent asks why the infant is “not starting from zero” immunologically even before vaccines. Which factor provides the most important systemic protection in the first months?
Read DetailsA 58-year-old works in construction and has years of unprotected noise exposure. He complains of persistent high-pitched ringing in both ears, worse at night. Otoscopic exam is normal. Audiometry shows high-frequency hearing loss. You explain that the most common mechanism relates to peripheral auditory damage, with downstream central “gain” changes contributing to the perception of sound without an external stimulus. Tinnitus most commonly results from:
Read DetailsA 26-year-old patient with a known peanut allergy presents to the emergency department with acute onset of wheezing, facial edema, urticaria, hypotension, and tachycardia within minutes of accidental exposure. The patient is in respiratory distress with audible stridor and a blood pressure of 82/48 mm Hg. Epinephrine 1mg IM is administered immediately. Which mechanism best explains why epinephrine is lifesaving in this patient’s condition?
Read DetailsA 27-year-old with a complete spinal cord injury at T4 is brought in with pounding headache, flushing above the lesion, diaphoresis, severe hypertension, and bradycardia after a blocked Foley catheter. You suspect a life-threatening reflex sympathetic discharge triggered by a noxious stimulus below the lesion level. Autonomic dysreflexia occurs most often in:
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