What is the Difference Between Olfactory and Gustatory Receptors

The main difference between olfactory and gustatory receptors is that the olfactory receptors are responsible for the sense of smell whereas the gustatory receptors are responsible for the sense of taste. 

Olfactory and gustatory receptors are two types of receptors responsible for providing the basic senses of the body. Furthermore, olfactory receptors occur at the top back of the nasal vault while gustatory receptors occur on the upper surface of the tongue.

Key Areas Covered

1. What are Olfactory Receptors
     – Definition, Structure, Role
2. What are Gustatory Receptors
     – Definition, Structure, Role
3. What are the Similarities Between Olfactory and Gustatory Receptors
      – Outline of Common Features
4. What is the Difference Between Olfactory and Gustatory Receptors
      – Comparison of Key Differences

Key Terms

Action Potential, Gustatory Receptors, Mucus, Olfactory Receptors, Smell, Taste

What are Olfactory Receptors

Olfactory receptors are the nerve cells sensitive to the smell or olfaction. They occur in a small region of the superior nasal cavity called the olfactory epithelium. Moreover, the dendrites of the olfactory receptors extend into the mucous membrane.

Figure 1: Olfactory Receptors

The airborne molecules inhaled through the nose dissolve in the mucus and transported to the dendrites of the olfactory receptors. The binding of these odorant molecules to the protein receptors on the plasma membrane of dendrites activates a G protein-coupled signaling pathway to produce an action potential on the olfactory receptor cell. Furthermore, this action potential reaches the olfactory bulb of the brain through the axon of the olfactory nerve. From the olfactory bulb, this axon divides and travel into different regions of the brain responsible for the recognition of the smell.

What are Gustatory Receptors

Gustatory receptors are the nerve cells sensitive to the taste or gustation. Our tongue consists of bumps called papillae. Within the papillae, taste buds occur, which contains the gustatory receptor cells. These cells are sensitive to the chemicals in the food.

Figure 2: Gustatory Receptors

Basically, out tongue is sensitive to four types of tastes. They are the salty taste, sweet taste, bitter taste, and the sour taste. Therefore, four types of gustatory receptors occur on the tongue to sense each type of taste. In sensing the salty taste, the high sodium concentration outside the gustatory receptors produces an action potential on the receptor cells.

Furthermore, lowering saliva pH is the stimulus to the gustatory receptors sensitive to the sour taste to produce an action potential. However, the other two tastes produce their action potentials through G protein-coupled receptors. That means; the chemicals responsible for the sweet taste and bitter taste do not enter into their gustatory receptor cells.

Similarities Between Olfactory and Gustatory Receptors

• Olfactory and gustatory receptors are two types of receptors responsible for the basic sensation of the body.
• Furthermore, both types of receptors are bipolar neurons with dendrites facing the external surface; axons pass through the internal surface, forming nerves.
• Moreover, they are sensitive to different chemicals delivered through fluids or air.
• Also, these receptors are embedded along with supporting cells and basal cells.
• Besides, both are the same in marine animals while reptiles use the tongue as an accessory olfactory organ.

Difference Between Olfactory and Gustatory Receptors

Definition

Olfactory receptors refer to any of the specialized, nucleated cells of the mucous membrane of the nose that serve as the receptors for smell while gustatory receptors refer to the cells on the tongue specialized to sense the taste. Thus, this is the main difference between olfactory and gustatory receptors. 

Type of Sense

Moreover, olfactory receptors sense the smell while the gustatory receptors sense the taste.

Occurrence in the Body

Olfactory receptors occur at the top back of the nasal vault while gustatory receptors occur on the upper surface of the tongue.

Occurrence in the Surface

Another difference between olfactory and gustatory receptors is that olfactory receptors occur beneath several cell layers while gustatory receptors occur at the surface.

Number of Chemicals

A large number of molecules can produce sensation with olfactory receptors while only a fewer number of molecules can produce sensation with the gustatory receptors.

Types

A single type of olfactory receptors occurs while several types of gustatory receptors occur based on the type of taste to which they are sensitive on the tongue. Hence, this is another difference between olfactory and gustatory receptors.

Conclusion

In brief, olfactory receptors are the nerve cells found at the top back of the nasal vault and are responsible for sensing the smell. On the other hand, gustatory receptors are the nerve cells that occur on the tongue, which are responsible for sensing the taste. Based on the taste, there are several types of receptors. Therefore, the main difference between olfactory and gustatory receptors is the type of sense to which they are sensitive.

References:

1. “Gustation and Olfaction|Anatomy and Physiology.” Lumen Learning, Lumen, Available Here

Image Courtesy:

1. “1403 Olfaction” By OpenStax –  (CC BY 4.0) via Commons Wikimedia  
2. “1402 The Tongue” By OpenStax –  (CC BY 4.0) via Commons Wikimedia