Final answer:
The sympathetic nervous system activates the release of catecholamines such as epinephrine and norepinephrine, leading to increased blood pressure by elevating heart rate, heart contractility, and consequently, cardiac output.
Step-by-step explanation:
Activation of the sympathetic nervous system can cause short-term increases in blood pressure by increasing heart rate, heart contractility, and cardiac output. When the sympathetic nervous system is activated, it triggers the release of catecholamines, such as epinephrine (also known as adrenaline) and norepinephrine, which have direct effects on the cardiovascular system.
Epinephrine and norepinephrine cause the arteries to constrict, which increases vascular resistance, and enhances cardiac output, a measure of the volume of blood pumped by the heart per minute. This elevation in heart rate and stroke volume results in an increase in blood pressure and volume. Additionally, these catecholamines act as bronchodilators to increase air volume in the lungs and stimulate gluconeogenesis, the formation of glucose from non-carbohydrate sources, to prepare the body for rapid action.