PHYSIOL 404 EXAM 1 UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS
Question:
1. Fovea
Answer:
Region of the retina with the highest concentration of cone photoreceptors and highest visual acuity.
Question:
2. Macula
Answer:
Central region of the retina that contains the fovea.
Question:
3. Optic disc
Answer:
Region of the retina where the optic nerve exits the eye.
Question:
4. Why the optic disc causes a blind spot
Answer:
The optic disc contains no rods or cones, so light cannot be detected there.
Question:
5. Location of optic disc relative to fovea
Answer:
The optic disc is nasal to the fovea.
Question:
6. Why the blind spot is temporal in the visual field
Answer:
Light from the temporal visual field strikes the nasal retina where the optic disc is located.
Question:
7. Visual field
Answer:
The area of the environment that can be seen by an eye at a given time.
Question:
8. Retinal image inversion
Answer:
Light travels in straight lines, causing superior visual field to map to inferior retina and temporal field to
map to nasal retina.
,Question:
9. Snellen numerator
Answer:
Distance from the chart at which vision is tested.
Question:
10. Snellen denominator
Answer:
Distance at which a person with normal vision can read the same line.
Question:
11. Meaning of worse visual acuity
Answer:
A larger Snellen denominator indicates poorer visual acuity.
Question:
12. Convergence of gaze
Answer:
Inward rotation of the eyes to focus on a near object.
Question:
13. Physiological diplopia
Answer:
Normal double vision of objects not located at the point of fixation.
Question:
14. Cause of physiological diplopia
Answer:
Images fall on non-corresponding retinal locations.
Question:
15. Corresponding retinal points
Answer:
Retinal locations that, when stimulated simultaneously, produce a single image.
Question:
16. Near object diplopia mechanism
Answer:
Image falls temporal to the fovea when eyes are focused on a far object.
Question:
17. Far object diplopia mechanism
Answer:
Image falls nasal to the fovea when eyes are focused on a near object.
, Question:
18. Phototransduction
Answer:
Conversion of light energy into an electrical signal by photoreceptors.
Question:
19. Photoreceptor type for color vision
Answer:
Cone photoreceptors.
Question:
20. Photopigment
Answer:
Opsin protein bound to retinal.
Question:
21. Retinal
Answer:
Vitamin A derivative responsible for absorbing photons.
Question:
22. 11-cis retinal
Answer:
Inactive form of retinal before photon absorption.
Question:
23. All-trans retinal
Answer:
Active form of retinal after photon absorption.
Question:
24. Photoisomerization
Answer:
Conversion of 11-cis retinal to all-trans retinal by light.
Question:
25. Effect of photoisomerization on opsin
Answer:
Causes opsin to activate intracellular signaling cascade.
Question:
26. Transducin
Answer:
G-protein activated by opsin during phototransduction.
AND CORRECT ANSWERS
Question:
1. Fovea
Answer:
Region of the retina with the highest concentration of cone photoreceptors and highest visual acuity.
Question:
2. Macula
Answer:
Central region of the retina that contains the fovea.
Question:
3. Optic disc
Answer:
Region of the retina where the optic nerve exits the eye.
Question:
4. Why the optic disc causes a blind spot
Answer:
The optic disc contains no rods or cones, so light cannot be detected there.
Question:
5. Location of optic disc relative to fovea
Answer:
The optic disc is nasal to the fovea.
Question:
6. Why the blind spot is temporal in the visual field
Answer:
Light from the temporal visual field strikes the nasal retina where the optic disc is located.
Question:
7. Visual field
Answer:
The area of the environment that can be seen by an eye at a given time.
Question:
8. Retinal image inversion
Answer:
Light travels in straight lines, causing superior visual field to map to inferior retina and temporal field to
map to nasal retina.
,Question:
9. Snellen numerator
Answer:
Distance from the chart at which vision is tested.
Question:
10. Snellen denominator
Answer:
Distance at which a person with normal vision can read the same line.
Question:
11. Meaning of worse visual acuity
Answer:
A larger Snellen denominator indicates poorer visual acuity.
Question:
12. Convergence of gaze
Answer:
Inward rotation of the eyes to focus on a near object.
Question:
13. Physiological diplopia
Answer:
Normal double vision of objects not located at the point of fixation.
Question:
14. Cause of physiological diplopia
Answer:
Images fall on non-corresponding retinal locations.
Question:
15. Corresponding retinal points
Answer:
Retinal locations that, when stimulated simultaneously, produce a single image.
Question:
16. Near object diplopia mechanism
Answer:
Image falls temporal to the fovea when eyes are focused on a far object.
Question:
17. Far object diplopia mechanism
Answer:
Image falls nasal to the fovea when eyes are focused on a near object.
, Question:
18. Phototransduction
Answer:
Conversion of light energy into an electrical signal by photoreceptors.
Question:
19. Photoreceptor type for color vision
Answer:
Cone photoreceptors.
Question:
20. Photopigment
Answer:
Opsin protein bound to retinal.
Question:
21. Retinal
Answer:
Vitamin A derivative responsible for absorbing photons.
Question:
22. 11-cis retinal
Answer:
Inactive form of retinal before photon absorption.
Question:
23. All-trans retinal
Answer:
Active form of retinal after photon absorption.
Question:
24. Photoisomerization
Answer:
Conversion of 11-cis retinal to all-trans retinal by light.
Question:
25. Effect of photoisomerization on opsin
Answer:
Causes opsin to activate intracellular signaling cascade.
Question:
26. Transducin
Answer:
G-protein activated by opsin during phototransduction.
