The answer is the endogenous opiate.
The human body naturally produces its own opiates like substances and uses them as neurotransmitters. These substances include endorphins, enkephalins, and dynorphin, often collectively known as endogenous opioids. Endogenous opioids modulate our reactions to painful stimuli.
The electron transport chain is the final step in cellular respiration and this process occurs along the inner membrane of our mitochondria .Inside our mitochondria ,the cells energy producing organelle,there is a membrane.
Answer:
A
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