Lecture 15: Vision Flashcards
What neurotransmitter does photoreceptors secrete?
Glutamate
The amount of light reaching the retina is controlled by the what
IRIS
The Ciliary muscle helps to what
Control the shape of the Lens
What are the 4 layers of protection of the eye
Eyeball
Eyelid
Eyelashes
Tears
Describe the Iris
Controls amount of light that can enter by using 2 set of smooth muscles
Circular = constricts Radical = Dilates
Describe the Pupil
opening where light enters
Describe the Lens
Focus light on the retina (Fovea
Describe the Sclera
Fluid filled spherical structure
Visible white layer of the eye
tough layer of connective tissue
Describe the Cornea
Fluid filled spherical structure
Anterior
Transparent layer that lets light rays through
Describe the Choroid
Fluid filled spherical structure
Contains blood vessels nourishing retina
Contains melanin under retina
Underneath Sclera
Describe the retina
Fluid filled spherical structure
Filled with Rods and cones
Axons of visual nerve fibers
Outer pigment cells
Describe the Posterior cavity
Fluid filled
Between lens and retina
Gelantinous viterious humor
Describe the anterior cavity
Fluid Filled
Between cornea and lens
Aqueous humor
What two things dilate or constrict the pupils
Circular/ radical muscles
Actions of the PNS/SNS
The Lens bends ____
Light rays
Accommodation in talking about vision relates to what
focusing
When were looking at something from a distant describe the eye
Lens flat, weak
Ciliary muscles relaxed
Ligaments tight
when were looking at something near, describe the eye
Lens rounded, strong
Ciliary muscles contracted (PNS stimulated)
Slack Ligaments
What is the main neurotransmitter involved in accommodation and why
ACh
causes contraction of ciliary muscles and constriction of rings
Describe Myopia and how its cured
Near-sightedness
Focal point falls before the retina
Corrected with concave lens )0
Describe Hyperopia and how its cured
Far-sightedness
Focal point falls behind retina
Corrected with Convex lens (0
Describe Presbyopia and how its cured
Aging
Ability to shape lens is lost
Corrected with bifocal (reading glasses)
Describe Rods
More Grayscale High sensitive low acuity Lots Converge on ganglion cells Located in peripheral retina
Describe cones
less Colour vision Lower sensitive High acuity Located in Fovea
What do Ganglion cells do
process visual information that begins when light enters eye
What do horizontal cells do
Help integrate and regulate input from photoreceptors and provide IPSP feedback to rods and cones
what do Bipolar cells do
Located between photoreceptors and ganglion cells
Directly or indirectly transmit signals from photoreceptors to ganglion cells
Describe Zonules
Fibrous strands connection ciliary body and lens
Describe the Orbit
Eye socket
Where is rhodopsin located
disk of rods and cones
How is rhodopsin made
Opsin + Retinal
What happens when it is dark
Rhodopsin inactive cGMP high
Cells depolarized constantly by Na+ and Ca+
What happens when its light
Rhodopsin bleached by light activates it
Decrease in cGMP = CNG channels to close, hyperpolarizing the cell
Less transmitter released onto bipolar cells
