How does the response of action potential from the heated gl

How does the response of action potential from the heated glass rod differ from an unheated glass rod? Provide a brief explanation for this difference.

Solution

A trigger for generation of action potential can be of various types. This also includes a heated rod as a stimulus. Accordingly, when a heated rod is applied on the skin, it causes the temperature of a very small area to increase enoromously and suddenly activates the thermoreceptors of that area. The thermoreceptors are closely attached to sensory endings of the nerve fibres and send a signal to the brain through these nerves. These sensory nerves traverse the signal of excessive heat and pain towards the brain and from there, the brain sends a reaction signal towards the motor nerve endings. As a reactional signal is received by the motor nerve endings, they quickly transmit this signal to the muscle fibres and cause motion in them. As a result, the mucles get activated and suddenly move the skin/body part away from the heated rod.

On the contrary, no activation of heat/pain receptors takes place when a non-heated glass rod is applied and hence, no transmission of signal takes place to and fro the brain. This results in no motion of muscles and hence non-withdrawl of the body part.

As it can be seen from the above explanation, there is a difference between the two situations when glass rod is applied. When heated, the glass rod activates the thermoreceptors and causes sudden trigger of action potential. On the other hand, an unheated rod fails to do the same. This also suggests that the heated rod causes the thermal threshold to increase and hence suddenly trigger the action potential.