Which of the following is NOT a trigger for a sympathetic nervous system response?

Hyperoxia, or an excess of oxygen in the tissues, is not a trigger for a sympathetic nervous system response. The sympathetic nervous system is primarily activated in situations that require the body to mobilize energy and resources, such as during stress or danger. This response is often linked to situations that involve lower oxygen levels, heightened anxiety, or increased physical demands like heavy work of breathing.

Increased work of breathing, anxiety, and hypoxia all serve as stimuli for the sympathetic nervous system due to their association with stress and the body's need to respond energetically. For example, high levels of anxiety can trigger the "fight or flight" response, increasing heart rate and expanding airways. Similarly, hypoxia indicates low oxygen levels, prompting the sympathetic system to enhance breathing and circulation in efforts to restore oxygen balance.

Hyperoxia, on the other hand, indicates an adequate or excessive supply of oxygen, which does not provoke a sympathetic response and can actually lead to a decrease in the drive to breathe, as the body senses that oxygen levels are sufficient.