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Smell & Taste
Next Generation: MS.LS1.8 MS.LS1.8

Smell & Taste

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Description:

This lesson will describe how receptors allow you to detect smells & tastes and will will describe the link between taste and smell.

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Tutorial

What's Covered

Welcome to this lesson today on taste and smell. Today, you will be learning about taste and smell as chemical senses. Specifically, you will look at:

  1. Chemical Senses
  2. Taste
  3. Smell

1. Chemical Senses

Taste and smell are chemical senses, which means that in order for our brain to be able to interpret a taste or smell it has to interpret the chemical makeup of the substance that makes the taste or the smell. Chemoreceptors are the receptors that receive sensory information about taste and smell and then relay that information to your cerebral cortex for interpretation.

Term to Know

    • Chemical senses
    • Special senses that are detected by highly specialized, chemical receptors (olfaction and gustation) that detect dissolved chemicals and gases; olfactory and gustation receptors are encapsulated nerve endings that are embedded with mucous membranes (olfactory) or muscle & epithelial tissues (gustation).

2. Taste

The technical term for taste is gustation and taste buds are scattered all over in your mouth, not just on your tongue, as some people would believe. You have taste buds scattered within your mouth that contain taste receptors, and these taste buds are on your tongue, on the sides of your cheeks, on the roof of your mouth, and in your throat.

Term to Know

    • Taste receptors
    • Encapsulated receptors found within taste buds; taste buds are located on lingual papillae on the tongue, in the roof of the mouth and your throat; there are 5 different tastes that human taste buds are capable of detecting.

What happens is that saliva will enter the pore of a taste bud and come in contact with these taste receptors. Then those receptors will stimulate a sensory neuron and the sensory neuron will relay that information to your brain.

The five common tastes or the five primary tastes that we have are sweet, salty, bitter, sour, and umami. You might be familiar with those first four and can think of something that's sweet tasting, salty, bitter, or sour. However, umami is something that you may not have heard of before and basically, this taste describes something that is savory; such as meat. Flavor can be a combination of those five tastes or any combination of those five tastes.

Terms to Know

    • Sweet
    • Foods that are naturally rich in carbohydrates elicit the sensation of sweetness; there are also artificial compounds designed to stimulate sweetness (artificial sweeteners).
    • Salty
    • Foods that are rich in salts/minerals elicit the sensation of saltiness (sodium, calcium salts, etc).
    • Sour
    • A perception of taste triggered by acidic foods (example: citrus fruits).
    • Bitter
    • A perception of taste often associated with spoiled or undesirable foods (examples: sour milk, nicotine).
    • Umami
    • A perception of taste triggered by amino acids and is often associated with savory foods (example: meat).

Take a look at the diagram below to give you a little bit better idea of how taste works at the cellular level.

Here you have a picture of a tongue where the the five main categories of taste are located. On the sides of the tongue you have sour, then you have sweet on the tip of the tongue. You have bitter towards the back of the tongue, and then you have salty that is found along the edges around the front of the tongue.

You can also see the pores on the image; saliva will enter these pores and come in contact with the taste buds and your taste buds are made up of these taste cells and their associated sensory nerves. These sensory nerves will relay the incoming information about the taste or the flavor to the brain.


3. Smell

The technical term for smell is olfaction and olfactory receptors located in your nose detect substances that are vaporized or water soluble. When you smell something you're smelling something that's vaporized or water soluble. Odor molecules attach to those receptors in the nose of the olfactory epithelium which are found withing a layer of tissue in your nasal cavity. The associated neurons will become stimulated and nerve impulses will travel to the olfactory bulbs in the brain. From there, the signal is forwarded to the cerebral cortex, where your brain will then interpret what the smell is. Is it lemon? Is it a pine tree? Is it cotton candy? What is that smell?

Term to Know

    • Olfactory receptors
    • Receptors embedded within the mucous membranes of the nose that are specialized in detecting odor molecules/various odors; encapuslated nerves that synapse with the olfactory bulb on the superior/upper aspect of the roof of the nose.
IN CONTEXT
If you've had a head cold you can't taste your food very well. If your nose is stuffed up, you're not getting that input from olfactory receptors and therefore, it dulls the taste or the flavor of that food which means taste and smell are very, very closely linked. In order to be able to taste things, we need to be able to smell.

Take a look at the diagram below to give you a little bit better idea of how smell works at the cellular level.

Down underneath there is where you would have the nasal cavity. If you were to inhale, if you were to smell, the vaporized substance or the water soluble substance would enter through your nasal cavity.

Then you have your olfactory receptors, located within the olfactory epithelium, where odor molecules would attach and the olfactory receptors go up and they connect with the olfactory bulb in the brain. Then the olfactory nerves within the olfactory bulb will carry that information up towards your cerebral cortex.


Summary

So this lesson has been an overview on taste and smell as chemical senses.  Remember, that in order to smell or taste, the body must interpret the chemical make up first! 

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Chemical senses

    Special senses that are detected by highly specialized, chemical receptors (olfaction and gustation) that detect dissolved chemicals and gases; olfactory and gustation receptors are encapsulated nerve endings that are embedded with mucous membranes (olfactory) or muscle & epithelial tissues (gustation).

  • Olfactory receptors

    Receptors embedded within the mucous membranes of the nose that are specialized in detecting odor molecules/various odors; encapuslated nerves that synapse with the olfactory bulb on the superior/upper aspect of the roof of the nose.

  • Taste receptors

    Encapsulated receptors found within taste buds; taste buds are located on lingual papillae on the tongue, in the roof of the mouth and your throat; there are 5 different tastes that human taste buds are capable of detecting.

  • Sweet

    Foods that are naturally rich in carbohydrates elicit the sensation of sweetness; there are also artificial compounds designed to stimulate sweetness (artificial sweeteners).

  • Salty

    Foods that are rich in salts/minerals elicit the sensation of saltiness (sodium, calcium salts, etc).

  • Sour

    A perception of taste triggered by acidic foods (example: citrus fruits).

  • Bitter

    A perception of taste often associated with spoiled or undesirable foods (examples: sour milk, nicotine).

  • Umami

    A perception of taste triggered by amino acids and is often associated with savory foods (example: meat).