| Answer | Crossword Clue |
|---|---|
| PIANOKEYS | They activate hammers |
| acetylcholine | a substance secreted at the ends of nerve fibres when they activate muscles |
| acetylcholines | ACETYLCHOLINE, a substance secreted at the ends of nerve fibres when they activate muscles |
| endorphins | Any of a group of hormones secreted within the brain and nervous system and having a number of physiological functions. They are peptides that activate the body's opiate receptors, causing an analgesic effect |
| PIANOS | They have lots of hammers |
| EARS | They have hammers and anvils. |
