The Fish eye Flashcards
1
Q
The fish eye has a _____ shape
A
- hemispheric
2
Q
What are the 7 main components of the fish eye?
A
- cornea
- iris
- lens
- retina
- choroid
- falciform process
- sclera
3
Q
What is refraction?
A
- bending light as it passes through media of different density (focus)
4
Q
Describe the cornea (3)
A
- outermost transparent layer
- thinner
- little refraction between cornea and water (density difference is small)
5
Q
Describe the iris
A
- controls amount of light entering eye
6
Q
Describe the lens (2)
A
- refracts more to focus light on retina
- distance between lens and retina varies (near/far-field vision)
7
Q
What is the shape of the lens in bony fish and lamprey?
A
- spherical
8
Q
What is the shape of the lens in elasmobranchs?
A
- slightly flattened
9
Q
Describe the retina (3)
A
- light detection + transolution to nerve signal
- thin, transparent
- back of eye
10
Q
Describe the outer layer of the retina (2)
A
- pigmented epithelium absorbs light after it passes photoreceptors
- photoreceptors detect light
11
Q
Describe the inner layer of the retina (3)
A
- nervous tissue
- nuclei of photoreceptors
- nerves
12
Q
Describe the choroid (3)
A
- highly vascularized (O2 deliver)
- reflects light passing through retina
- reflective guanine crystals to increase light sensitivity in low light levels
13
Q
What does rete mirabile do? (2)
A
- enhances O2 delivery to eye (demanding)
- root shift increases O2 unloading
14
Q
Describe the sclera (2)
A
- eyeball structure w connective tissue (whites of eye)
- outer layer
15
Q
What is the composition of the sclera in agnathans?
A
- fibrous sclera
