Which potential side effect can result from excessive stimulation of the autonomic nervous system?

Increased secretion of mucus is a potential side effect of excessive stimulation of the autonomic nervous system, particularly through the parasympathetic branch. The autonomic nervous system regulates involuntary bodily functions, including glandular secretions. When the parasympathetic system is overly stimulated, it can lead to an increase in mucus production in the airways, as this division is responsible for promoting secretions that aid in protecting and lubricating respiratory tissues.

This reaction can be particularly pertinent in certain conditions where the autonomic balance is disrupted, such as in response to irritants or allergens, where an exaggerated parasympathetic response results in excessive mucus, which can obstruct airways and complicate respiratory function.

By contrast, the other options do not align with the effects of excessive stimulation in the same way. Decreased heart rate typically results from increased parasympathetic activity, and a reduced pH in the blood, indicating acidosis, would not directly follow from autonomic stimulation but rather relate to metabolic or respiratory disturbances. Improved airway clearance generally results from proper autonomic balance, where mucus production is maintained at optimal levels rather than excessive.