Eye Structure Flashcards
Eye definition
the organ of sight allowing imaging of surroundings
Types of simple eyes
- Pinhole
- Refracting
- Reflecting
What is the protein part of the visual pigment called
Opsin
What are the two main types of opsins found in the human eye and their locations
- Rhodopsin- rod cells of retina
- Photopsins- cone cells of retina
What are crystallins
Structural proteins of lenses
How long ago did eyes evolve in multicellular organisms
540-490 million years ago
- during the cambrian explosion
What type of eyes do 1. Arthropods (insects, arachnids, myriapods)
2. Vertebrates have?
- Athropods- compound eyes
- Vertebrates- simple yes
Difference between simple and compound eyes
Compound eyes- complex structure made up of numerous ommatidia, provides a wide field of view, lower resolution
Simple eyes- consist of a single lens/ fewer lenses, more limited field of view, usually higher resolution relative to size
What are the structures of the 3 layers of the eye
OUTER- sclera, cornea
MIDDLE- uvea (choroid, ciliary body, iris)
INNER- retina
Functions of each of the 3 layers of the eye
Outer- protective
Middle- vascular and pigmented
Inner- photoreceptive
Function of the dioptric apparatus
Refraction of light
What structures make up the dioptric apparatus
cornea, lens, aqueous humour, vitreous humor
*all components with refractive properties
Which structure is responsible for majority of light refraction
Cornea (70%)
What eye structure is an outgrowth of the central nervous system
Retina
What photoreceptors are, responsible for 1. low light
2. High light levels
- Rods- low light
- Cones- high light
What area of the aye has the highest concentration of cones
Fovea
How old are the oldest fossils with eyes
About 500 million years old
What is the average diameter of the adult human eye
25mm
What structures make up the anterior segment of the eye
cornea, aqueous humour, iris, cilliary body, lens
What structures make up the posterior segment of the eye
vitreous, retina, choroid
What is the most important property of the cornea
Transparency
What is the refractive index of the cornea
1.376
What is the refractive index of aqueous humor
1.336
