Question

1. True or False (circle one): Hyperactivation (i.e. extreme activation) of sensory receptors like Meisner’s corpuscles or Merkel’s discs allows for nociceptive information to be conducted to the primary sensory cortex.

Explain your answer to the question immediately above. If the answer is true, explain how these receptors use graded potentials to differentiate between touch and nociception. If the answer is false, explain how touch and nociceptive stimuli activate different structures and/or channels in their respective axons. Please give examples for each.

Answer 1

Answer is true: Hyperactivation (i.e. extreme activation) of sensory receptors like Meisner’s corpuscles or Merkel’s discs allows for nociceptive information to be conducted to the primary sensory cortex.

Explanation: Merkel’s disks are found to be present in the upper layers of skin near the base of the epidermis. Pain is the another name given to nociception, which is the neural processing of harmful stimuli in response to some tissue damage. Nociception starts at the sensory receptors, but pain doesnot start until it is communicated to the brain. There are various nociceptive pathways which are going to and through the brain. Most of the axons carrying nociceptive information into the brain via spinal cord, direct it to the thalamus region and their neural signal undergoes final processing in the primary somatosensory cortex.

- explain how these receptors use graded potentials to differentiate between touch and nociception.

Merkel’s disks and Meissner’s corpuscles are located in the upper layers and can specifically confine even mild touch. Large receptors are located in the lower layers of the skin and respond to deeper touch. And thus finally primary somatosensory cortex and secondary cortical areas in the brain are responsible for processing the climax picture of stimuli transmitted from the interaction of mechanoreceptors.

When tissue is damaged, certain chemical substances are released from the cells, and these substances activate the chemosensitive nociceptors. Mechanoreceptive nociceptors have a high inception for activation, they respond to mechanical stimulation that is so intense it might damage the tissue. Sensory information which is collected from the receptors and free nerve endings travels up to the spinal cord and is then transmitted to the medulla, thalamus, and ultimately to somatosensory cortex.