Module 1 The Nervous System

1.1.5 page 5

Try This 6

To review, you may choose to do questions 5 and 7 on page 418 of the text

Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), 416, fig. 12.18. Reproduced by permission.

Module 1: Lesson 5 Assignment—Defect/Disorder Table

As you worked through this lesson, you learned about the different structures of the eye and about their functions in facilitating vision. You were also introduced to some disorders that are the result of one or more of these structures malfunctioning.

Self-Check

To ensure that you have mastered the concepts of this lesson, you may wish to do the self test which includes a numerical response question as well as a closed written response question. This is an excellent opportunity to practice for the types of questions that will be presented on the Diploma Exam.

Use the following information to answer question 1:

Visual Interpretation

The brain integrates visual information from both eyes. Some of the steps in the visual pathway are shown below. Please note that these steps are NOT in the correct order and that NOT all steps are part of the visual pathway.

1. rods and/or cones change light energy into a nerve impulse

2. nerve impulse travels to the temporal area of the brain for sorting

3. nerve impulse travels to the occipital lobe of the cerebral cortex for interpretation

4. ganglion cells are stimulated

5. nerve impulse leaves eye via the auditory nerve

6. light energy enters the eye and strikes the retina

1. In the four spaces below, record the number of the four steps that are part of the visual pathway. Record the steps in the correct order in which they occur during the visual pathway.
   
   ____  ____  ____  ____
2. There are two chief types of light sensitive cells (called X and Y in this question) in the healthy human retina but they are not evenly distributed. An investigation on the distribution of sensory cell types X and Y across an area of the retina (shown as PQ on the diagram below) was developed.
   
   
   
   The relative numbers of cell types X and Y were more or less constant except in positions R and S. Using relative numbers, the following graph indicates the relative frequency of sensory cell type X along the axis PQ.
   
   

1. 1. Identify cell type X
   2. Identify cell type Y
   3. What structure is represented by region R?
   4. What structure is represented by region S?
2. Copy the graph above and clearly superimpose a curve to indicate the relative frequency of cell type Y along the axis PQ.

The diagram below represents the different states of the iris in bright and in dim light.

3. 1. What structures are represented by M and N?
   2. Briefly explain what causes the iris of eye B to have a different appearance than that of eye A.