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.
Quick Answer. According to the Centers for Disease Control, the flu is most contagious five to seven days after flu symptoms develop. The flu can even be contagious one day before any flu symptoms develop.