I'm new here and this is one of the first things i've done on this site but to answer the question, i believe the answer is amino acids
Evolution does not occur in a straight line with one species another in a series of orderly steps with living species that are closely related share a common trait. I hope my answer has come to your help. God bless and have a nice day ahead!
Explanation:
Temprature:the body must maintain a relatively constant temperature if it gets to hot the body employees vasodilation to cool down this delites the blood vessels allowing more heat to escape from them through the skin
Glucose: the body must regulate glucose levels to stay healthy. When glucose levels become to high the body realeases a hormone called an insulinwhen they become to low the body converts the glocogenin the blood to glucose
Toxins :in the blood can distrupt the body's homeostasis thus it signals the urinary system to ensure that the toxins are excreated
Because if you take care of your body/organs by exercise and good diet then your bidy will stay healthy without sickness which results in longer life span
I think it is the nervous system