Hormones -- such as melatonin and cortisol; the former signals the body to go to bed, while the latter signals for the sleeping person to wake up -- are created by physiological changes.
<span>Of course feeling like you are going to die is probably the most important priority. Although a heavy weight on your chest can be a dangerous and critical symptom, it still is not as critical as feeling like you are going to die.</span>
The right choice of them is biosphere, community, and organism.
Answer:
immune system
Explanation:
The adaptive immune system reacts specifically to pathogens (germs). It is able to recognize attacking pathogens and fights against certain antigens or foreign substances. The next time a known antigen is encountered, the adaptive immune system can respond faster.
