1) Opioid peptide 
Hemorphins are a class of naturally occurring, endogenous opioid peptides which are found in the bloodstream, and are derived from the β-chain of hemoglobin. They have antinociceptive effects via activation of the opioid receptors, and some may also play a role in blood pressure through inihibition of the angiotensin-converting enzyme (ACE), as w...