Review Note

While playing soccer, 14 yr old girl experiences difficulty breathing, exhibits intense anxiety, cyanosis, sweating, wheezing, heart rate is 120 bpm.  EMTs administer O2, then transport to ER.  Staff physician at ER administers β2-adrenergic agonist via inhaler.  Her breathing improves, but she reports fatigue.

Question: The difficulty breathing before treatment is attributable to;
{{c1::Narrowing of pathways caused by smooth muscle contraction::

1. Fatigue in skeletal muscles involved in breathing
2. Narrowing of airways caused by edema
3. Narrowing of pathways caused by smooth muscle contraction
4. Decreased levels of ATP in airway smooth muscle}}