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.
According to the Centers for Disease Control and Prevention, people with the flu can transmit the virus a day before they even begin to show symptoms. They will continue to be contagious for about five to seven days after they develop the symptoms. According to Flu.gov, children and people with compromised immune systems may be contagious for a longer period.