Visual system- optics and transduction Flashcards
How much of our cerebral cortex does our visual system use
over 1/3
What actually is light
Electromagnetic radiation
What is the wavelength range of visible light
400-700nm
What does the wavelength of light determine
Hue- red light has the longest wavelength, violet the shortest
What does the wave amplitude of light determine
Intensity or brightness
What primarily determines the width of the visible light spectrum
The spectral absorbances of the photopigments in the eye
What allows us to view the back of the eye
Opthalmoscope or fundus camera
What is the macula
A spot at the centre of the retina, focused on clear straight-ahead vision
What is within the macula
The fovea- very high cone density, used for high acuity vision
What is the optic disk
Where cells of retina send their axons together in the optic nerve through the optic disk to the brain
What is the retina
Light sensing part of the eye
What causes our blind spot
The optic disk has no rods and cones as it is where the optic nerve leaves the eye
Why don’t we see our blind spot
The brain fills in the hole with surrounding patterns
Where is the aqueous humour vs vitreous humour
Aqueous humour- between the iris and the inner surface of the cornea
Vitreous humour- between the lens and optic nerve
What does the aqueous humour do
Carries O2 and nutrients to the structures within the eye, bathes them, and removes waste products (blood would prevent transparency)
What is vitreous humour
Gelatnious substance that accounts for 80% of the eye’s volume, fills the space between the lens and optic nerve
What does the vitreous humour do
Helps maintain the spherical shape of the eye, contains phagocytic cells that remove blood and debri that might interfere with light transmission
What is choroid
A pigment within the pigmeted epithelium that helps absorb any stray light to prevent it reflecting back into the eye and distorting the image
Where are the eyes suspended
In orbits of the skull
What are the extraocular muscles
Attached to the sclera- we use them to move our eye all the time eg tracking objects allows light to come into the fovea for high acuity vision
What do light rays pass through as they travel through the eye
Transparent structures- the cornea, lens, fluid compartments
What keeps the vascularity of the eye to a minimum
Cleansing function of aqueous humour, function of the choroid in nourishing the retinal layers
Where in the eye do blood vessels avoid
Avoid the fovea at the centre of the macula that provides the greatest visual acuity
What features minimise optic distortion
Transparet structures, minimised vascularity, no blood vessels in fovea, pigmented epithelium