What is the Difference Between Tonic and Phasic Receptors?

Tonic and phasic receptors are two types of sensory receptors that differ in their adaptation rate to stimuli. Here are the main differences between them:

• Tonic Receptors: These receptors adapt slowly to a stimulus and convey messages about the duration of the stimulus. They respond to the stimulus as long as it persists and produce a continuous frequency of action potentials. Examples of tonic receptors include pain receptors, muscle spindle, joint capsule, and Ruffini corpuscle.
• Phasic Receptors: These receptors adapt rapidly to a stimulus and convey messages about the changes in the stimulus, such as intensity. They respond quickly to stimuli but stop responding upon continuous stimulation, leading to a decrease in action potential frequency during prolonged stimulation. An example of a phasic receptor is the Pacinian corpuscle.

In summary, tonic receptors are slow-adapting receptors that provide information about the duration of a stimulus, while phasic receptors are rapid-adapting receptors that convey information about changes in the stimulus.

Comparative Table: Tonic vs Phasic Receptors

Here is a table summarizing the differences between tonic and phasic receptors:

Tonic receptors convey messages about the duration of the stimulus, while phasic receptors convey messages about the changes in the stimulus. Tonic receptors are slow-adapting and provide a graded response, whereas phasic receptors are fast-adapting and provide a rapid response that decreases in time.