Neuro-5 Flashcards
What are the electroreceptors on sharks?
The ampullary electroreceptors which are the amullae of lorenzini
Wha tare the eyes of flatworms?
They are photoreceptors which have screening pigments which allows detection of the direction of light and allows the organism to undergo negative photo taxis allowing the organism to avoid dessication
What are the eyes of insects?
These are compound eyes which consist of a ommatidia which each have their own light focusing lens
This type of eye is very good at detecting movement
Why is the eye a globe?
This allows the eye to rotate in 3D space to stabilize it so that a clear image can be produced despite the time delay in processing
What are the basic components of the human eye?
A lens which focuses light on the retina
Cornea which covers the eye
Pupil which controls the light intensity
The bulk of the eye is filled with vitreous humour (fluid)
The retina contains the receptors which respond to light
What is the arrangement of the photoreceptors and neurons in the eye?
The light must first pass through the bipolar neurons these activate ganglion cells which can signal the information to the brain
The bipolar neurons themselves are activated by receptors
What is the function of horizontal and amacrine cells?
These become activated by bipolar cells, they will then go on to inhibit the ganglion cells which are adjacent to it this creates the on centre and off surround system used in human eyes which allows rapid change of light intensity which does not affect our ability to see if the change is symmetrical
It also makes us very sensitive to movement and conscious of contrasting environments
What is the fovea?
This is the area where we do most of our fine vison
As this area is small the eye must make constant small movements to keep a clear image of what is going on around the organism
How do cones provide colour vision?
There are three types that respond differently to different wave lengths
Blue cones have a narrow range with a peak near 419nm
Green cones have a broader range with a peak near 531 nm
Red cones have a very broad range with a peak near 588nm
These provide the brain with information about the relative amounts of each type of light from which the whole colour spectrum is recreated
What is acuity?
The detail which can be seen, this is very good in birds of prey which have acuity about 8 times better than that of humans
What is sensitivity with regards to eyes?
This is the eyes ability to operate in low light levels
Where is colour vision really good?
In tropical marine habitats where the stomatopods
What behavioural tests showing the stomatopods have colour vision?
Through use of coloured cubes and a food reward where the animal would swim towards the colour
What is unique about the stomatopod eye?
It has six rows of receptors which contain 12 cone-like sensors (as opposed to humans 3) which makes it the worlds most complex retina
