The key difference between tonic and phasic receptors is that tonic receptors convey messages about the duration of the stimulus, while phasic receptors convey messages about the changes in the stimulus.
Sensory receptors are present in the body internally and externally, and they are activated through different stimuli. These receptors respond during an interaction of the body with the internal or external environment. Therefore, sensory receptors respond to light, mechanical, chemical, nociceptive, and thermal stimuli. Once the sensory receptors are activated, they generate an action potential that propagates along the axon to reach the central nervous system. Different types of receptors adapt to stimulations that last longer in different ways. Such receptors are of two types: tonic and phasic receptors.
CONTENTS
1. Overview and Key Difference
2. What are Tonic Receptors
3. What are Phasic Receptors
4. Similarities – Tonic and Phasic Receptors
5. Tonic vs Phasic Receptors in Tabular Form
6. Summary – Tonic vs Phasic Receptors
What are Tonic Receptors?
Tonic receptors are receptors that gradually adapt and inform about the duration of the stimulus. They usually respond to stimuli as long as it remains. This produces a continuous frequency of action potentials. Therefore, tonic receptors carry information for a duration of the stimuli. The response to these stimuli is slow. Examples of tonic receptors are pain receptors, muscle spindles, joint capsules, and Ruffini corpuscles.
What are Phasic Receptors?
Phasic receptors are receptors that adapt and inform rapidly and mainly focus on the change of the stimulus. These receptors usually respond faster to stimuli; however, the response is stopped upon continuous stimulation. Therefore, with a prolonged period of stimulation, the action potential decreases. This conveys information about changes, such as the intensity of the stimuli, and does not provide information on the duration of the stimulus. The response of these receptors diminishes very fast and stops. Examples of phasic receptors are Pacinian corpuscles or lamellar corpuscles. These receptors are present among the four main mechanoreceptors that are situated in the hairless skin of mammals.
What are the Similarities Between Tonic and Phasic Receptors?
- Tonic and phasic receptors are sensory receptors.
- Both receive signals from the sensory organs.
- They act in response to a stimulus.
- Moreover, they generate an action potential that propagates along the axon
What is the Difference 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. Thus, this is the key difference between tonic and phasic receptors. Moreover, tonic receptors adapt slowly to a stimulus, while phasic receptors adapt rapidly to a stimulus. Examples of tonic receptors are pain receptors, muscle spindle, joint capsule, and Ruffini corpuscle, while an example of a phasic receptor is the Pacinian corpuscle.
The following table summarizes the difference between tonic and phasic receptors.
Summary – Tonic vs Phasic Receptors
Tonic and phasic receptors are sensory receptors present in the body. Tonic receptors convey messages about the duration of the stimulus. On the other hand, phasic receptors convey messages about the changes in the stimulus. Tonic receptors are receptors that gradually adapt and inform about the presence and strength of a stimulus. Phasic receptors are receptors that adapt and inform rapidly and mainly focus on the rate of change of receptors. So, this summarizes the difference between tonic and phasic receptors. However, both receptors receive signals through the different sensory organs and function to generate action potentials.
Reference:
1. “Adaptation of Sensory Receptors.” Biophysics, Department of Physiology &, et al. “Adaptation of Sensory Receptors.” SpringerLink, Springer Berlin Heidelberg.
2. “Modalities of Sensation – Nociceptors – Hyperalgesia.” TeachMePhysiology, 23 Aug. 2021.
Image Courtesy:
1. “Blausen 0809 Skin TactileReceptors” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014” WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia