7. Key Concept: What are the main features of the retina? Describe each of these features.
The _________ contains a large number of _________ for detailed vision; the _________ is an area with a high density of _________ in the center of the _________ ; and the _________ which has optic nerve fibers and no photoreceptors.
8. Key Concept: How does the eye bend light to focus on objects at different distances?
For objects at greater distances, the _________ relaxes, increasing tension in the _________ and _________ the _________ to bend light _________ . For _________ objects, the _________ muscle contracts, _________ tension on the lens so that it rounds up to bend light more.
9. Key Concept: How does the shape of the eyeball affect focusing of light on the retina?
In the case of a shorter than normal eyeball, the _________ cannot round up enough, so light rays focus behind the _________ when viewing near objects (_________ ). When the eyeball is too long, the _________ cannot _________ enough, so light rays focus in front of the _________ when viewing distant objects (_________ ).