The key difference between mechanoreceptors and proprioceptors is that mechanoreceptors respond to external mechanical stimuli and can vary in their distribution, whereas proprioceptors respond to internal mechanical stimuli and are restricted to bones and muscles.
Receptors are a variety of biomolecules primarily present on the plasma membrane and respond to a wide variety of stimuli. So, mechanoreceptors and proprioceptors are two types of receptors that respond to mechanical stimuli. Their receptor action is mediated via the ion gated channels. Therefore, the activation leads to a nervous transmission.
CONTENTS
1. Overview and Key Difference
2. What are Mechanoreceptors
3. What are Proprioceptors
4. Similarities Between Mechanoreceptors and Proprioceptors
5. Side by Side Comparison – Mechanoreceptors vs Proprioceptors in Tabular Form
6. Summary
What are Mechanoreceptors?
Mechanoreceptors are a group of somatosensory receptors. Therefore, they rely on the intracellular signal transduction mechanism received through the ionotropic channels. The stimuli can be touch, pressure, stretch stimuli, sound or motion. These mechanoreceptors are mostly present in the superficial skin or the deep layers of the skin. However, it can also be present near bones. These mechanoreceptors can either be encapsulated or un-encapsulated.
There are various types of mechanoreceptors. They are the Merkel’s disks, Meissner’s corpuscles, Ruffini endings, and Pacinian corpuscles. These mechanoreceptors show varied distribution. Merkel’s disks are found in the tips of fingers, the external genitalia, and the lips. The Meissner’s corpuscles are found in the epidermis of the glabrous skin on the fingers, palm, and sole. The Ruffini endings are present in the deep skin, ligaments, and tendons, while the Pacinian corpuscles are present in the subcutaneous tissue of the skin.
Figure 01: Mechanoreceptors
The mechanoreceptor function depends on the disruption caused in the receptors upon the flow of ions. It will then activate the generation of the action potential, leading to the mechano-transduction and the initiation of mechanical forces in response to the stimuli. These receptors usually arise from the neural crest cells. They develop during embryonic development and undergo full maturation in the post-natal period.
What are Proprioceptors?
Proprioceptors are a type of mechano-sensory neurons. They are usually present within muscles, tendons, and joints. There are different types of proprioceptors that are activated in different instances. It can be limb velocity and movement, limb load and limb limits. This is called proprioception or the sixth sense.
Proprioception is mainly mediated by the central nervous system and the stimuli such as vision and the vestibular system. Proprioceptors are distributed throughout the body. The three basic types of proprioceptors are muscle spindles, Golgi tendon organs, and Golgi tendons.
Figure 02: Proprioception
The activation of the proprioceptors takes place at the periphery. They are specific nerve endings that facilitate act on the proprioceptors. They are specific receptors for pressure, light, temperature, sound and other senses. These receptors are also mediated by ion gated channels. The proprioceptors also develop during embryonic development.
What are the Similarities Between Mechanoreceptors and Proprioceptors?
- Mechanoreceptors and proprioceptors are receptors responding to mechanical stimuli.
- Both are mediated by ion gated channels.
- They initiate a nerve impulse transmission upon the activation of the particular receptor.
- Both develop during embryonic development.
- Moreover, they have nerve endings that stimulate the receptor.
What is the Difference Between Mechanoreceptors and Proprioceptors?
The key difference between mechanoreceptors and proprioceptors is the type of stimuli to which they respond. Mechanoreceptors respond to external stimuli while proprioceptors respond to internal stimuli. Therefore, the distribution of these receptors and different subtypes also vary between the two main receptor types. Mechanoreceptors are found in the superficial or deep layers of the skin while proprioceptors are found in muscles or tendons. So, this is another difference between mechanoreceptors and proprioceptors.
Merkel’s disks, Meissner’s corpuscles, Ruffini ends, and Pacinian corpuscles are examples of mechanoreceptors while muscle spindles, Golgi tendon organs, and Golgi tendons are examples for proprioceptors.
Summary – Mechanoreceptors vs Proprioceptors
Mechanoreceptors are a broad group of receptors that respond to external mechanical stimuli. Proprioceptors are a group of mechanoreceptors that are restricted to the muscles and the tendons. Besides, proprioceptors respond to internal stimuli mainly and facilitate in the movement responses. Mechanoreceptors can be Merkel’s disks, Meissner’s corpuscles, Ruffini ends or Pacinian corpuscles. Meanwhile, Proprioceptors can be muscle spindles, Golgi tendon organs or Golgi tendons. So, this summarizes the difference between mechanoreceptors and proprioceptors.
Reference:
1. Iheanacho, Franklin. “Physiology, Mechanoreceptors.” StatPearls [Internet]., U.S. National Library of Medicine, 25 Apr. 2019, Available here.
2. Purves, Dale. “Mechanoreceptors Specialized for Proprioception.” Neuroscience. 2nd Edition., U.S. National Library of Medicine, 1 Jan. 1970, Available here.
Image Courtesy:
1. “Figure 36 02 02” By CNX OpenStax – (CC BY 4.0) via Commons Wikimedia
2. “Proprioception signals” By Thomas.haslwanter – Own work (CC BY-SA 3.0) via Commons Wikimedia