We judge foods by tasting them. Have you ever wondered how does your sense of taste work? If not, then here's the answer for your question.
The sense of taste is also called 'gustation' and it is accompanied by salivation. It works in conjunction with the sense of smell, and the sense of sight. All of these senses together make sure that we do not consume foods that are poisonous or rotten.
This explains why we salivate at the sight or the aroma of our favorite foods. Irrespective of the sensation of taste, personal preferences may influence your gustation.
The Taste Receptors
We often attribute the sensation of taste to the taste buds on our tongue. A taste bud is just a cluster of taste receptor cells. The taste receptor cells are responsible for the detection of taste. Each taste bud contains about 50-150 columnar receptor cells, which have transmembrane proteins at the apex.
These proteins bind to certain tastants, while they simply admit other tastants into the cell. The taste buds are mounted on the fungiform papillae. The papillae are situated on the surface of the tongue.
The gustation is possible only when the taste receptor cells are able to respond to the tastants. The tastants are molecules or ions, which stimulate the sense of the taste.
The 5 major taste sensations are : Salty: Substances like table salt lead to this sensation. Bitter: Compounds like quinine cause this taste. Sweet: Generally, foods with sucrose content cause this taste sensation. Sour: This sensation can be termed as the taste of acids. Umami: This taste is caused due to glutamate or monosodium glutamate (MSG) in foods.
Perception of Taste
When we ingest food, it comes in contact with the fungiform papillae. Now, the tastants from the ingested food reach the taste buds and seep through its pores to reach the taste receptor cells. For each sensation, a different kind of reaction takes place. Every receptor cell is connected to a sensory neuron through a synapse.
A neuron can be connected to several receptor cells from various taste buds. The respective signal for a particular taste sensation is first sent to the neuron, and from the neuron it is transmitted to the gustatory cortex, which is situated at the rear side of the brain.
This cortex processes the stimulus that gives respective results to the brain. This is how we perceive the taste of any substance.
What Happens When?
In this section, we will be considering a few examples corresponding to the various sensations of taste, and tell you what happens at the taste receptor cell when the respective tastant reaches it.
Taste Sensation: Salty Example: Table Salt
When table salt is consumed, the Na+ ions in it, are directly permitted into the receptor cells. This causes the cell to get depolarized and release energy at the synapse, thereby generating an action potential in it.
Taste Sensation: Bitter Example: Orange
When you eat an orange, the quinine in it, binds to the G-protein coupled receptors at the surface of the receptor cells and triggers the stimulus. T2R subunits of taste receptors are associated with this taste.
Taste Sensation: Sweet Example: Table Sugar
On the intake of table sugar, the sucrose molecules in it bind to the G-protein coupled receptors, thereby triggering the signal. T1R1 and T1R3 subunits of taste receptors are associated with this taste.
Taste Sensation: Sour Example: Lemon
A lemon is an acidic substance. When you have a lemon, the H+ ions in them, enter the taste receptor cells. This leads to a reaction that results in an action potential, which sends the stimulus to the sensory neuron.
Taste Sensation: Umami Example: Parmesan Cheese
On consuming the Parmesan cheese, the glutamate in them, undergo binding to the G-protein coupled receptors. The subunits of receptors associated with this sensation of taste are T1R2 and T1R3.
Some taste disorders are:
Phantom Taste: When one experiences a taste that does not really exist, he is experiencing phantom taste.
Ageusia: Here, the person is unable to taste anything.
Hypogeusia: This condition occurs when a person's power to taste reduces.
Dysgeusia: Here, the person experiences a foul taste in his mouth all the time.
Did You Know?
Cats cannot sense the sweet taste.
At birth, humans have around 10,000 taste buds and we start losing a few taste buds after the age of 50.
There are taste buds on the roof of the mouth and on the throat lining.
In order to get the flavor of food, you should use olfaction, that is, your sense of smell, along with gustation. You now know the working of sense of taste. So the next time you have your favorite food, you know what's happening inside.