The response mechanism
If your horse feels pain due to a horsefly bite on the leg, pain-sensitive cells in his skin will feel it and release neurotransmitters, which start the transmission of the signal up to the spinal cord through the nerves to the sensory neurons. They will then bounce this signal to the brain’s neurons. “The need for a very quick response will also generate a reflex, which involves the sensitive neurons sending the information to the motor neurons in the spinal cord, creating the reaction of moving the leg quickly, for instance,” explains Leticia. In the brain, this information will reach the pain sensation area, be analysed and a more developed response will be generated (such as moving the leg out of the way or kicking in defence). This will be sent to the motor neurons of the spinal cord’s grey matter. This command will then exit the spinal cord through the correspondent spinal nerve, down smaller nerves until it reaches the necessary muscles needed to do the job. All of this happens in a split second.
Something as simple as a fly b ite w ill s park a c hain rea ction JANUARY 2019