Question

Do all hormones are chemical signals?

Answer 1

YES all hormones are chemical signals

Answer 2

Chemical Signals

Chemical signals are molecules that affect the behavior of those cells that have receptor proteins to receive them. For example, a hormone that binds to a receptor protein affects the metabolism of the cell.
    Hormones fall into two basic chemical classes. As noted in Table 10.1, most are peptide hormones, a category that includes not only those that are peptides but also proteins, glycoproteins, or modified amino acids. The remainder are steroid hormones, each having the same four-carbon ring complex, but with different side chains.

How Hormones Function
     Most peptide hormones bind to a receptor protein in the plasma membrane. This often leads to the conversion of ATP to cyclic AMP (cyclic adenosine monophosphate, abbreviated cAMP) . In cAMP, one phosphate group is attached to the rest of the molecule at two spots. The peptide hormone is called the first messenger, and cAMP is called the second messenger. (Calcium is also a common second messenger, and this helps explain why calcium regulation in the body is so important).