3.3.1 Vision II Flashcards
What are the covered parts?
What is the pathway of aqueous humor flow?
Ciliary body → posterior chamber → pupil → anterior chamber → Canal of Schlem
What allows for contraction and dilation of the pupil?
An inner sphincter muscle - constricts the pupil
Outer radial muscle - dilates the pupil
Describe the beginning of signal processing in the retina?
Photoreceptors transduce photons into neuronal activity and synapthic processing begins in the retina.
Ganglionic cell axons will travel to the thalmus
What are the covered parts?
Where must light be focused to initiate processing of visual signals?
Light must be focused precisely on the neural retina
What are the two locations in the eye at which light is refracted?
Cornea - static refraction
Lens - dynamic refraction
What is the difference between a hyperopic eye and a mypoic eye?
Hyperopic eyes tend to have a focal length that is behind the retina in space, thus making them “far-sighted”
Myopic eyes tend to have a focal length that is located in front of the retina, thus making them “near-sighted”
What is presbyopia?
Lens of the eye hardens making it resistance to changes in shape
How is a map of the external environment created on each retina?
Humans have binocular vison, what does this mean?
Both eyes can focus on a single space - unlike a fish
Vision from the left side of the visual field is interpreted where? Right side?
Structures distal to the optic chiasm contain a retina map of?
The contralateral visual field with contributions from both eyes for binocular regions
Visual fields outside the binocular region must be?
Decussate to reach the contralateral side of the brain
What is the process by which visual transduction occurs in photoreceptor outer segements?
After absorption of a photon and shifting to all-trans retinAl, what happens in the visual signal transduction pathway?
Light stimulation will close Na channels leading to hyperpolarization of the photoreceptor membrane. This will then reduce glutamate release.
Describe the levels of glutamate released by photoreceptor rods in the dark vs in the light?
Dark - high amounts of glutamate
Light - low amounts of glutamate is releases
Describe the properties of the photoreceptor rods.
Operates in dim light, and can detect a single photon of light
Many rods, many bipolars, one ganglion - meaning low acuity
Sacrifices acuity to gain sensitivity
Found in periphery of retina
Describe the properties of photoreceptor in the cone system.
Operates in bright light
Few cones, one bipolar cells, and one ganglion cell - maximum acuity
High density in the fovea
Different opsins sensitive to different wavelengths of light.
Describe the different layers of this image.
Throwing you a curve ball! Figure this one out on our own. Look at the image from earlier in the slides and determine what layers correspond to which :)
Presense of any exogeneous substance (ex. blood) in the vitreous humor can do what?
reduce visual acutiy or may result in blind spots
Optic nerve fibers are myelinated by?
Oligodendrocytes
And are bathed in CSF
Inner retinal layer have blood supplied by?
Branches of the central retinal artery
During development what supplies blood to the photoreceptors?
Retinal pigment epithelium
Describe the distribution of rods and cones throughout the eye.
How are visual signals processed into visual pathways?
With the retina, bipolar and ganglion cells are tuned to detect contrast.
Neurons at each level of the pathway have receptive fields defined by location and complexity.
Receptive fields become more complex as one moves to higher centers of the pathway.
