Final answer:
Metoclopramide manages nausea primarily by blocking dopamine receptors in the brain's vomiting center, the area postrema, and indirectly promotes gastric emptying by strengthening the pyloric sphincter.
Step-by-step explanation:
The mechanism of action of metoclopramide in managing nausea is by blocking dopamine, which affects the vomiting center in the brain, known as the area postrema. This area is responsible for triggering emesis in response to various stimuli, including motion sickness and toxins in the blood. Metoclopramide antagonizes dopamine receptors in the area postrema, which helps alleviate symptoms of nausea. Additionally, it enhances gastric motility by strengthening the pyloric sphincter, which in turn increases gastric emptying, but this is a function complementary to its antiemetic properties.