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.
How long is the flu contagious, and how long does the flu last? The flu is typically contagious about 24-48 hours before symptoms appear (from about the last day of the incubation period) and in normal healthy adults is contagious for another five to seven days.