Answer:
Sinoatrial Node?
Explanation:
Blood pressure drops whenever the vagus nerge is stimulated. In fact, babies have to constantly be monitored for position, becase cranial pressure can stimualte the vagus nerve and cut heart circulation by inhibitng the Sinoatrial node.
The answer is probably air.
True, a vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.