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.
Flu Contagious Period Flu starts being contagious about 24 hours before you have symptoms. You're most contagious when you first get sick and for the following 2 to 3 days.