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Module 1 The Nervous System

Lesson 1.1.4

1.1.4 page 3

Taste

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Pizza! You could just taste it. To understand the sensation of taste, read pages 425 and 426. You may wish to make summary notes or support your learning with diagrams. Store this information in your course folder for reference.

 

taste bud: a sensory organ composed of a taste pore, taste cells, and sensory fibres of a sensory neuron involved in initiating taste sensations

When you smelled the aroma of pizza, you started to salivate. This is a polite term for drool! Taste buds on the surface of the tongue can only detect a taste when chemicals are dissolved on the tongue so that chemoreceptors can start an impulse to the brain. There are four basic tastes—salty, sweet, sour, and bitter. Try resting a sour candy on various parts of your tongue as you see in “Figure 12.25” on page 426 of the textbook. You’ll get the idea of where various taste receptors are located on your tongue!

 

Your taste likes and dislikes appear to have a homeostatic value, or an indicator for what the body may need to retain or restore homeostasis. A liking for sugar and salt helps satisfy the body’s need for carbohydrates, minerals, and some amino acids.  Because many poisons and spoiled foods are bitter, a person’s dislike of bitter food is an instinctive, protective response.

Self-Check

Complete the Taste Reception Handout below. After you have checked your answers, store your work in your course folder for reference when you study.

Taste Reception Handout
  1. What four basic tastes do most scientists agree are sensed by most people? Name at least one food that illustrates each taste.
  2. Supertasters are people whose sense of taste is significantly more sensitive than the average person. Hypothesize how the anatomy of taste reception may differ in a supertaster as compared to a normal person.
  3. Explain why the taste bud is considered a “sense organ.”
  4. Hypothesize whether the taste buds which are sensitive to saltiness are the same taste buds which are sensitive to bitterness or sweetness.
  5. Draw a flow chart to illustrate the taster’s steps from taste reception to interpretation.
Check your work.
Self-Check Answers

Answers to Taste Reception Handout

  1. Most people are able to taste salty, sour, sweet, and bitter.

    • A salty taste is mostly due to sodium ions, as in table salt. Calcium ions can also produce the salty taste.
    • A sour taste is due mainly to the presence of hydrogen ions as in most acidic foods including oranges, lemons, and tomatoes.
    • A sweet taste is perceived when sugars and some proteins are present.
    • A bitter taste is characteristic of coffee, unsweetened chocolate, beer, uncured olives, tonic water, and aspirin.
  1. Supertasters may have more papillae, they may have more taste buds, or they may have more taste cells in the taste buds than the average person.
  2. A taste bud is considered to be a sense organ because it is composed of several types of cells, such as the taste cell with its modified ending of hairs, and the sensory neuron which is depressed into a pore where it captures chemicals from foods. The cells work together to initiate the nerve impulse.
  3. Taste buds sensitive to saltiness may be different than those sensitive to sweetness or bitterness because they may have different receptors on the hair portion of the taste cell that different chemicals fit into.
  4. Chemoreceptors in taste buds detect chemicals in food which trigger sensory neurons to communicate nerve impulses to the brain. There, the parietal lobe, located in the cerebrum, interprets these impulses as a sensation.