Which of the following effects are mediated by the sympathetic nervous system?

• A. Bladder contraction
• B. Increased heart rate
• C. Decreased lung capacity
• D. Pupil constriction

Answer: (B)

The sympathetic division drives rapid, energy-raising responses that prepare the body for activity. It typically speeds up heart rate, increases airway openness, dilates pupils, and relaxes organs that would hinder quick action (like the bladder). Among the options, bladder contraction is a parasympathetic effect, and pupil constriction is also parasympathetic. The idea of decreased lung capacity would contradict the sympathetic action of bronchodilation, which actually increases airway openness. Therefore, the effect that aligns with sympathetic activity is an increased heart rate, since the sympathetic system raises heart rate to boost cardiac output during activity.