Test Your Knowledge ofTerms and Facts
Match the vestibular organ on the left 9. with its correct component on the right.
1. utricle and saccule a. cupula
2. semicircular canals b. ciliary body
4. The dissociation of rhodopsin in the rods in response to light causes a. the Na+ channels to become blocked.
b. the rods to secrete less neurotransmitter.
c. the bipolar cells to become either stimulated or inhibited.
5. Tonic receptors a. are fast-adapting.
b. do not fire continuously to a sustained stimulus.
d. are described by all of these.
6. Cutaneous receptive fields are smallest in a. the fingertips.
c. the thighs.
7. The process of lateral inhibition a. increases the sensitivity of receptors.
b. promotes sensory adaptation.
c. increases sensory acuity.
d. prevents adjacent receptors from being stimulated.
8. The receptors for taste are a. naked sensory nerve endings.
b. encapsulated sensory nerve endings.
c. specialized epithelial cells.
Which of these statements about the utricle and saccule are true?
a. They are otolith organs.
b. They are located in the middle ear.
c. They provide a sense of linear acceleration.
Since fibers of the optic nerve that originate in the nasal halves of each retina cross over at the optic chiasma, each lateral geniculate receives input from a. both the right and left sides of the visual field of both eyes.
b. the ipsilateral visual field of both eyes.
c. the contralateral visual field of both eyes.
d. the ipsilateral field of one eye and the contralateral field of the other eye.
When a person with normal vision views an object from a distance of at least 20 feet, a. the ciliary muscles are relaxed.
b. the suspensory ligament is tight.
c. the lens is in its most flat, least convex shape.
d. all of these apply.
Glasses with concave lenses help to correct a. presbyopia.
b. the superior colliculus.
c. the inferior colliculus.
d. the striate cortex.
14. A bar of light in a specific part of the retina, with a particular length and orientation, is the most effective stimulus for a. ganglion cells.
b. lateral geniculate cells.
c. simple cortical cells.
d. complex cortical cells.
15. The ability of the lens to increase its curvature and maintain a focus at close distances is called a. convergence.
17. Stimulation of membrane protein receptors by binding to specific molecules is not responsible for a. the sense of smell.
b. sweet taste sensations.
c. sour taste sensations.
18. Epithelial cells release transmitter chemicals that excite sensory neurons in all of these senses except a.
TestYour Understanding of Concepts
1. Explain what is meant by lateral inhibition and give examples of its effects in three sensory systems.1
2. Describe the nature of the generator potential and explain its relationship to stimulus intensity and to frequency of action potential production.
3. Describe the phantom limb phenomenon and give a possible explanation for its occurrence.
4. Explain the relationship between smell and taste. How are these senses similar? How do they differ?
5. Explain how the vestibular apparatus provides information about changes in the position of our body in space.
6. Describe the sequence of changes that occur during accommodation. Why is it more of a strain on the eyes to look
1Note: This question is answered in the chapter 10 Study Guide found on the Online Learning Center at www.mhhe.com/fox8.
at a small nearby object than at large objects far away?
7. Describe the effects of Light on the photoreceptors and explain how these effects influence the bipolar cells.
8. Explain why images that fall on the fovea centralis are seen more clearly than images that fall on the periphery of the retina. Why are the "corners of the eyes" more sensitive to light than the fovea?
9. Explain why rods provide only black-and-white vision. Include a discussion of different types of color blindness in your answer.
10. Explain why green objects can be seen better at night than objects of other colors. What effect does red light in a darkroom have on a dark-adapted eye?
11. Describe the receptive fields of ganglion cells and explain how the
1. You are firing your laser canon from your position on the bridge of your starship. You see the hostile enemy starship explode, but you hear no accompanying sound. Can you explain this? How do receptors for sight and hearing differ?
2. People with conduction deafness often speak quietly. By contrast, people with sensorineural deafness tend to speak louder than normal. Explain these differences.
Opioid drugs reduce the sensation of dull, persistent pain but have little effect on the initial sharp pain of a noxious stimulus (e.g., a pin prick). What do these different effects imply? What conclusion can be drawn from the fact that aspirin (a drug that inhibits the formation of prostaglandins) functions as a pain reliever?
Compare the role of G-proteins in the senses of taste and sight. What is the nature of these fields helps to improve visual acuity.
12. How many genes code for the sense of color vision? How many for taste? How many for smell? What does this information say about the level of integration required by the brain for the perception of these senses?
advantage of having G-proteins mediate the effect of a stimulus on a receptor cell?
5. Discuss the role that inertia plays in the physiology of the vestibular apparatus. Why is there no sensation of movement in an airplane once it has achieved cruising speed?
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.