The autonomic nervous system (ANS) regulates the functions of our internal organs (the viscera) such as the heart, stomach and intestines.
The flu is contagious a day before and five days to a week after its onset. Young children, people over 65, those with compromised immune systems, and people with a terminal illness are at risk of death from the flu.
You're contagious from one day before you have any symptoms. You stay contagious for five to seven days after you start feeling sick. Kids may be able to spread the virus for even longer, until all their symptoms fade. From: How Long Is the Flu Contagious?