Because they have similar chemical structures, morphine and other opiates are able to lock into receptor sites for __________

A) GABA.
B) serotonin.
C) dopamine.
D) endorphins.

Endorphins

Natural, pain-relieving chemicals produced by the body, often released in response to stress or exercise, and associated with feelings of euphoria.

Morphine

A potent opiate analgesic drug derived from the opium poppy used to relieve severe pain.

Receptor Sites

Specific locations on cell membranes or within cells where specific substances like hormones, neurotransmitters, or drugs can bind and elicit a biological response.