Module 1 The Nervous System

Reflect and Connect (optional)

The sensations of smell and taste are closely related. In Biology 20 you learned about the respiratory system. Based on your knowledge of physiology, reflect on why is it more difficult to taste or smell food when you have a cold? Choose one of the following formats to illustrate how Lesson 4 fits with the previous three lessons:Prepare a concept map, a diagram, or a podcast. Remember to link the sensory receptors to the appropriate parts of the central or peripheral nervous system, and include the specific parts of the brain that are involved.

OR

In the Get Focused section of this lesson, you were asked to consider sensing the smell of pizza or a person’s fragrance, the taste of pizza, the temperature of the room, or the pain in your hand. Write a poem, make a comic strip, or draw diagrams which illustrate the communication and processing of one of these sensations. Include in your example the stimulus, the type of sensory receptor involved, the sensory neuron, and the part of the brain that is used.

Submit your work to your teacher.

Self-Chec

To ensure that you have mastered the concepts of this lesson, try these self-check multiple-choice questions. Check your answers and file your work in your course folder for a future review.

1. Identify the statement that best compares sensation to perception.

1. A sensation occurs when nerve impulses from the sense organs reach the cerebral cortex; perception is an interpretation by the brain about the meaning of sensations.
2. A sensation occurs when nerve impulses from the sense organs reach the spinal cord; perception is an interpretation by the spinal cord of the meaning of sensations.
3. A sensation occurs when nerve impulses from the sense organ bypass the spinal cord and go directly to the brain; perception is an interpretation by the sensory receptors of the meaning of sensations.
4. A sensation occurs when nerve impulses from the sense organs reach the cerebral cortex; perception is an interpretation by the peripheral nervous system of the meaning of sensations.

2. You walk into a pizza restaurant and immediately notice the smells associated with cooking pizza. After a few minutes, you no longer notice these odours. This phenomenon can be explained by a process called

1. sensory accommodation
2. a reflex arc
3. sensory adaptation
4. sensory perception

3. Which of the following is an INCORRECT match between the sensory receptor and the stimulus that it responds to?

1. photoreceptor—light energy
2. chemoreceptor—pressure
3. mechanoreceptor—sound waves
4. thermoreceptor—change in radiant energy

4. The olfactory receptors in a dog’s nose would be classified as

1. photoreceptors
2. mechanoreceptors
3. chemoreceptors
4. proprioceptors

5. Which of the following structures would you NOT mention if you were tracing the path involved in tasting something sweet?

1. taste bud
2. olfactory receptor cell
3. sensory neuron
4. parietal lobe of cerebrum

Use the following information to answer multiple-choice questions 6 and 7.

The tips of the fingers are sensitive enough to discriminate raised points on a surface, as well as the locations of these points. Knowing this, in the nineteenth century Louis Braille invented the Braille system of reading for blind people. Each letter of a language alphabet is represented by up to six raised dots. A blind person who has learned the Braille system can read up to 50 words a minute.

6. Will a person preparing Braille script have to know if the blind reader is left-handed or right-handed and, thus, change the order of the script accordingly?

1. No, because the sensations from both the right hand and the left hand are carried by the spinal cord into the same hemisphere of the cerebrum.
2. No, because the sensations received separately by the left and right cerebral hemispheres from the right and left hands are integrated before they are interpreted into language.
3. Yes, because the sensations from the right and left hands are carried to the left and right cerebral hemispheres, respectively, and therefore the information is interpreted in reverse order.
4. Yes, because the movements of the right and left hands are initiated by opposite sides of the cerebral cortex.

7. This sentence can be read using the eyes, but it can also be read using the fingertips if the sentence is printed in Braille. This fact illustrates that

1. the brain can form the same meaning from different sensations
2. nerve impulses initiated by touch are identical to nerve impulses initiated by sight
3. receptors for touch and receptors for sight respond to the same environmental stimuli
4. the lobe of the brain that receives sensory stimuli from the eyes is the same lobe that receives sensory stimuli from the fingers

Reflect on the Big Picture

Lesson 4 focuses on how you gather information about your environment through the senses of taste, smell, and touch. In the “Big Picture,” you gathered information about the scents of pizza and fragrance, the pain of a handshake, and the temperature of a room, This information had to be received by your sensory receptors and communicated through sensory nerve impulses to different lobes of the cerebrum, such as the temporal and occipital lobes.

The brain interprets this information and causes your body to feel something or to do something in response. If the perfume is pleasant you may move closer to the person, inhale more deeply, and you may feel pleasure. But remember the sneezing response that your friend had to the odours? Using the information from this lesson, reflect on these possible responses to a stimulus. Store this response in your course folder.