Box jellyfish venom contains a neurotoxin that prevents sodium and calcium from crossing a cell membrane. It also contains norepinephrine. Box jellyfish stings cause only a mild irritation with almost no marks. A half hour later, the victim may feel pain, cramps, nausea, vomiting and anxiety headaches, severe back pain and even a sense of doom. There is also a feeling of great stress and high blood pressure. These symptoms could then lead to heart failure and difficulty breathing, resulting in death. Identify a part of the brain or the endocrine system that detect a response to the following, after being stung by a box jellyfish pain__.