Q2: Receptors, The Eye Flashcards
Two main types of light receptors in the mammalian eye
Rod cell and cone cells
Rod cells and cone cells act as …
Transducers
Transducers
Rod and cone cells
Conserve light energy into the electrical energy of a nerve impulse.
Greater number of rod cells or cone cells?
More rod cells
Many or a single rod cell connected to a single sensory neurone in the optic nerve?
Many rod cells are connected to a single sensory neurone in the optic nerve.
Rod cells function
Rod cells are used to detect light of very low intensity.
What happens before a generator potential is created in bipolar cells that lots of rod cells are connected to?
A certain threshold value must be exceeded
Retinal convergence
Lots of rod cells connected to a single bipolar cell.
Retinal convergence effect on threshold value?
Means that it is likely to be exceeded
Why do rod cells only show images in black and white?
They cannot distinguish between different wavelengths of light.
Pigment in rod cells
Rhodopsin
Rhodopsin in rod cells must be broken down…
In order to create a generator potential
Low intensity light has enough energy to…
Cause breakdown of rhodopsin
How many types of rod cells
One
Why can’t the brain distinguish between separate sources of light that has stimulated rod cells?
The light received by rod cells sharing the same neurone will only generate one impulse which travels to the brain.
Visual acuity of rod cells?
Low visual acuity
How many types of cone cells?
Three
Each of the three types of cone cells responds to…
A different wavelength of light
Often cone cells are connected to
Their own bipolar cell connected to a sensory neurone in the optic nerve
Why do cone cells only respond to a high intensity of light?
Their stimulation cannot combine to exceed the threshold value and create a generator potential
Pigment in cone cells
Iodopsin
Iodopsin vs rhodopsin
Light intensity for breakdown
Iodopsin requires a higher light intensity for its breakdown than rhodopsin
Each type of cone cell contains…
So?
A specific type of iodopsin.
So each cone cells is sensitive to a different range of wavelengths of light.
Why do cone cells have good visual acuity?
Each cone cell has its connection to a single bipolar cell so eg: if two were stimulated, the brain would receive two separate impulses.
