Emergency Medical Technician (EMT) Intermediate Practice Exam

As perfusion decreases, which of the following does the sympathetic nervous system stimulate?

1. Increased production of neurotransmitters

2. A decrease in heart rate

3. A release of epinephrine and norepinephrine

4. Increased blood flow to non-vital organs

The correct answer is: A release of epinephrine and norepinephrine

The sympathetic nervous system plays a crucial role in the body's response to stress or decreased perfusion, which can occur due to various reasons like shock or hemorrhage. When perfusion decreases, the sympathetic nervous system is activated to help maintain adequate blood flow and support vital organ function. One of the primary responses facilitated by this activation is the release of epinephrine and norepinephrine. These hormones increase heart rate, strengthen heart muscle contractions, and promote vasoconstriction in non-essential areas while directing blood flow towards vital organs. The release of these neurotransmitters enhances the body's ability to respond to a decreased perfusion state by helping stabilize blood pressure and improving overall circulation. This mechanism is essential during emergencies, as it helps counteract the effects of reduced blood flow, ensuring that essential organs receive the necessary oxygen and nutrients. Thus, the release of epinephrine and norepinephrine is a critical component of the body's compensatory mechanisms during such events. The other options do not align with the sympathetic nervous system's typical responses to diminished perfusion. For example, a decrease in heart rate would be counterproductive in this context, whereas increased blood flow to non-vital organs would detract from the goal of preserving critical functions.