Kramer’s automatic response to the hot napkin is an example of a nociceptive reflex - a reflex caused by a painful or threatening stimulus.
Here’s what happens in that split second:
Sensory neurons carry the message (pain, heat) to Kramer’s spinal cord.
Motor neurons carry a signal from the spinal cord to Kramer’s muscles to move his hands away from the napkin.
Finally, Kramer perceives the pain of touching the hot napkin.
Reflex arcs (a type of neural pathway) allow a person to react to a dangerous stimulus before the sensory stimulation is processed in the brain. That means that Kramer actually moved before he felt the burn!