AEMCA Practice Exam

Where are Alpha 1 receptors located and what is the primary effect of their stimulation?

1. On the blood vessels, causing dilation

2. On the heart, increasing heart rate

3. On the blood vessels, causing constriction

4. In the brain, decreasing dopamine levels

The correct answer is: On the blood vessels, causing constriction

Alpha 1 receptors are primarily located on the smooth muscle cells of blood vessels. When stimulated, these receptors lead to vasoconstriction, which is the narrowing of the blood vessels. This response is crucial in regulating blood pressure and blood flow throughout the body. The stimulation of Alpha 1 receptors results in increased peripheral resistance, which raises blood pressure and enhances blood circulation to vital organs. The other options pertain to the functions or effects of different types of receptors or physiological processes. For instance, the dilation of blood vessels would be associated with beta receptors rather than Alpha 1 receptors. Similarly, increasing heart rate is primarily mediated by beta 1 receptors located in the heart, not Alpha 1 receptors. The option regarding the brain and dopamine levels does not correlate with the established functions of Alpha 1 receptors, as their primary role is not related to neurotransmitter regulation but rather to vascular function. Thus, the stimulation of Alpha 1 receptors directly correlates with the primary effect of inducing vasoconstriction in blood vessels.