Receptors In The Eye Flashcards
Rods
Where are they found?
Two features of them?(2)
Properties of rods and explanations?(2)
What type of animal has lots of rods? How do they make up for this?
What is many points of detail one nerve pathway described as?
Retina-periphery of the eye Low visual acuity-lots of rods go to one bipolar neurone which go to one ganglion cell Respond to low light-have low threshold Nocturnal animals other senses Convergence
Retina What is it associated with? What is it separated from this by? Called? What do these prevent? What does an optical nerve consist of? What may a ganglion neurone connect? What is a bipolar neurone? What does each cone have?
Choroid layer Layer of pigmented epithelial -melanin granules Internal reflection of light Axons from ganglion cell Bipolar neurones from 150 rods Connect many rods Own ganglion
Why is the mammalian retina described as inverted?
What’s an advantage of this?
What’s a disadvantage?
Light has to travel through layers of nerve before reaching photoreceptors
Cells close to blood supply to obtain O2
Has to pass through lots of cells
Photoreception What is rhodopsin composed of? What type of molecule are these each? Describe process(4) What is this process in terms of speed?
Opsin and retinene
Protein and lipid
Light causes rhodopsin to dissociate to opsin and retinene and retinene to change isomeric shape
Changes ion balance causing hyper polarisation and AP
In this form can longer respond to light-bleached
Enzymes reconvert retinene to original form and recombine with opsin to form rhodopsin
Slow
Cones
Where are they?
What is their structure?
Properties?(3)
Fovea of retina
Similar to rods but have iodopsin pigment
High visual acuity- each cone has own nerve pathway
Only respond to bright light- high threshold
3 kinds of cone each with own visual pigment
Fovea centralis
What property of the cone is this to do with?
Where is this point on the retina?
What does it have its own?
What is it packed with?
What’s it called when you bring an object close to your eye?
What does the eye do to the near point?
Visual acuity Directly behind lense Optical axis Very slim cone cells each with own visual pathway Near point Focuses on so can be seen in most detail
Trichromatic theory of colour vision
What do different cones respond to?
Although official colour observed at retina what does the final colour perceived depend on?
Different wavelengths of light
Integrative properties of brain
Differences of rods and cones (5)
Rods Low visual acuity Respond low light 120 million Many go to one ganglion At periphery
Cones High visual acuity Respond to bright light 7 million Each go to own ganglion Fovea
What do receptors in the eye do with light energy?
Transducer into electrical energy of a nerve impulse
