Organophosphate pesticide??? plz help me with this anatomy question! thanks..it would be greatly appreciated!!

Gregor, who works a pesticide factory, comes to the clinic complaining of muscle spasms that interfere with his movement and breathing. A blood test shows that he has been contaminated with organophosphate pesticide, which is an acetylcholinesterase inhibitor. How would you explain to Gregor what this means?