Vision Flashcards
(49 cards)
Where do photoreceptors communicate to?
Intermediate relay cells
What % of neurons is dedicated to vision?
30%
Where do intermediate relay cells communicate to?
retinal ganglion cells
What is the outermost layer of the eye?
Sclera
What is the innermost layer of the eye?
Retina
What is the intermediate layer of the eye?
Choroid
What is the choroid?
A vascular layer that forms the ciliary body
What is the ciliary body?
Muscles, Processes and ligaments arranged in a ring and attached to the iris
Where is the major site of refraction?
The interface between air and the cornea
What are the 3 common errors of vision?
Myopia, Astigmatism, Hypermetropia
What is accommodation?
A process where the lens adjusts its curvature to allow us to see near objects through a gain in refraction power, through the contraction of ciliary muscles
What regulates light entry?
Iris
What happens during the near response?
Lenses accommodate
pupils constrict
eyes converge
What cells detect physical energy in the eye?
Photoreceptors
How many types of rods is there?
1, for dim vision
How many types of cones is there?
3, red, blue, green for colours and daylight vision
Where is the transmitter that relays cells?
The end of the inner segment
What photopigment absorbs light?
Rhodopsin
What determines the wavelength sensitivity of photoreceptors?
The way the opsin holds the chromophore, which is different in each type of cone
What receptor class do visual pigments belong to?
G-protein coupled receptors
What does light activate to break down cyclic GMP?
Molecular cascade
cyclic GMP is used…
To hold open channels allowing sodium/calcium flow in a cell
What does light adaption achieve?
Photoreceptors can cope with constant background (daylight) light
Direction of gaze
Cones are activated by looking at an object, but rods aren’t (you have to look at an object to see the colour)
