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.
Someone with the flu is contagious for a day or so before symptoms start, then remains contagious for five to seven days once they appear. The CDC considers someone to be contagious until the fever is back to normal, without the help of medication, for 24 to 48 hours.