The following steps involved in a heartbeat from the movement the blood enters

The following steps involved in a heartbeat from the movement the blood enters The heart:
( must put these these in numerical order)

1- Atria contract
2- ventricles contract
3- atria relax
4- ventricles relax
5- atria and ventricles fill with blood   

#2) list four ways that public health has improved the control of infectious diseases in the 20th century



#3) antibiotics are prescribed for
A) cold and flu
B) for pathogens that have rapid antigenic variation
C) diseases Taft are difficult to treat without penicillin
D) bacterial infections such as S. Aureus