If a person steps on a sharp object it is detected in the foot by a and a message is fired off to the central nervous system?

If a person steps on a sharp object, pain receptors in the foot, known as nociceptors, detect the injury. These receptors send electrical signals through sensory neurons to the spinal cord and then to the central nervous system (CNS). The CNS processes this information and generates a response, such as the sensation of pain, prompting the person to withdraw their foot from the sharp object to prevent further injury.