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.
A person with flu is contagious for up to seven days after the onset of the illness, although the virus can be detected in the secretions up to 24 hours before the onset of symptoms. Thus, an individual can transmit the virus one day before symptoms begin.