Simplify the following text for a Grade 7 native English-speaking person.
Original: A number of specialized types of neurons exist : sensory neurons respond to touch , sound , light and numerous other stimuli affecting cells of the sensory organs that then send signals to the spinal cord and brain . Motor neurons receive signals from the brain and spinal cord , cause muscle contractions , and affect glands .
Simplified: Sensory neurons carry signals from sense organs to the spinal cord and brain .