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What Are Chemoreceptors?

In the nose, indirect chemoreceptors allow animals to smell.
Cells located on the tongue are direct chemoreceptors.
Chomoreceptors are sensory receptors that goven smell.
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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 11 November 2014
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Chemoreceptors are specialized nerve cells which are designed to respond to chemical stimuli. The body contains both direct and distant chemoreceptors, all of which play important roles in bodily function and daily life. These cells are also sometimes known as chemosensors, because they behave like sensors which “sniff” for specific chemicals of interest. Like other neurons, these cells are usually designed with customized locks which only fit the keys of specific chemicals, which makes them sensitive only to certain types of chemicals or chemical families.

An example of direct chemoreceptors are the cells located on the tongue. When people taste food, it is because these cells respond to the chemicals in the food, sending a signal to the brain to let the brain know about what's happening in the mouth. Specific regions of the mouth have areas which are targeted towards specific tastes, such as salty and sweet. This explains why foods can taste different as they are chewed and swallowed, and also why some foods have an aftertaste, as certain chemicals can take longer to stimulate the chemoreceptors.

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Direct chemoreceptors are also found in the carotid body, a structure located at the branch of the carotid artery. These nerves detect levels of oxygen and carbon dioxide in the blood to determine when someone needs to breathe. The carotid body explains why people cannot suffocate themselves by holding their breath, because these cells will eventually trigger an involuntary breathing response due to the critical levels of chemicals they detect in the blood. These cells can also monitor temperature and pH balance.

Indirect chemoreceptors can be found in the nose, sensing smells and detecting hormones. As many people have observed when they have a cold, their receptors in the mouth and nose are both involved in the process of taste, as foods will not taste right when the nose is congested, or when the tongue is damaged.

All of these nerve cells send impulses back to the brain. Chemoreceptors can also be found in the brain itself, monitoring pH level and alerting the brain to the presence of chemicals which could indicate a problem. A special area of the brain called the chemoreceptor trigger zone receives input from those receptors which are sensitive to chemicals which can be dangerous. When these cells send a message to the brain that those chemicals have been ingested, the brain triggers a vomiting reflex so that the chemicals will be voided from the body before they can be metabolized.

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irontoenail
Post 6

Something interesting I read about chemoreceptors recently, is that if you eat too much of certain foods, like, say garlic, you end up overwhelming the receptors in your nose and your mouth so that they can't taste it anymore.

Which is why often fancy restaurants will provide a "palate cleansing" of something like lime juice, or sorbet, so that the receptors will essentially be knocked clean and able to taste the flavors properly again.

This is a well known trick, and I know that a lot of tasters use it, for example, when drinking wine, or taste testing for a company.

lluviaporos
Post 5

I think chemoreceptors are responsible for some of the functions of the body as well. I remember reading that the way caffeine works is by basically mimicking the chemical in your body that makes you fall asleep.

It goes and attaches to the chemoreceptors in your brain where that chemical is supposed to go, so even if you feel tired and want to sleep, you can't, because the receptors have already been taken over.

KoiwiGal
Post 4

@Windchime - Something to consider is that often people will have more or less chemoreceptors on their tongue (as well as olfactory chemoreceptors). If you've got a lot of ability to taste sweetness and saltiness you're more likely to be overwhelmed by the salty than the sweet, which might guide some preference.

On the other hand, I read an article recently where they said that it's believed that people have their salt receptors basically trained to ignore large amounts of salt, which is why people are able to eat so much of it in junk food. They said in an experiment where people were made to eat food without salt for a couple of weeks, they went back to "normal" and considered the junk food they used to like too salty.

yumdelish
Post 3

I hate the way that food tastes weird when you have a cold. Considering that you rely on taste to know if something is fit to eat, it's better to stay with plain and safe food until you're recovered.

MissMuffet
Post 2

@Windchime - There are thought to be two ways the tongue's chemoreceptors detect taste. Simplistically, one detects salty flavors and the other sweet. Whichever is dominant in an individual will determine what they prefer to eat. I guess if something is easier to taste then you will choose to eat more of it.

Windchime
Post 1

Thanks for this straightforward explanation. I was struggling to understand what this term meant and now I will be able to finish my term paper much more easily.

I do have one question, about the way tongue chemoreceptors function. It's not a secret that some people have a sweet tooth, while others favor salty or savory food. Does this mean that the type of chemoreceptors we have varies between individuals?

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