Final answer:
The sympathetic nervous system increases heart rate and blood pressure in response to stress, as part of the 'fight-or-flight' response.
Step-by-step explanation:
Activation of the sympathetic nervous system is a response to decreased cardiac output that results in an increased heart rate and blood pressure. This is part of the body’s "fight-or-flight" response during stressful situations. When faced with stress, the sympathetic nervous system will act to prepare the body for rapid action by increasing cardiac output and the blood flow to essential areas, such as the muscles, while decreasing it to non-essential systems, like digestion. This increased cardiac output helps to ensure that the body has the necessary energy and resources to either fight the threat or flee from danger.