Vision Flashcards
Exam 2
What is the Sclera?
The white of the eye
Cornea
Clear covering of center of the eye
What are the two responsibilities of the cornea?
- Protection
- Bends light to focus on the lens
What is the iris?
The colored part of the eye
What does the lens do?
Changes shape to focus light on the retina
Choroid
Brown layer with blood vessels
Retina
Part of eye responsible for actual vision
What are the five parts of the retina?
- Photoreceptors
- Bipolar cells
- Ganglion cells
- Horizontal and amacrine cells
- Pigmented layer
Photoreceptors
Receive light and phototransduction
Bipolar cells
Conduct electrical signals from photoreceptors to ganglion cells
Ganglion cells
Conduct electrical signals, form optic nerve, and SEND ACTION POTENTIAL
Horizontal and amacrine cells
allow for lateral communication between neurons
Pigmented layer
Absorbs scatter
What is the pathway of light entering the eye?
Cornea -> lens -> retina -> pigmented layers -> photoreceptors
Light is reflected so that objects are _____________, but the ______ flips it
upside-down, brain
Once the light reaches the photoreceptors, next comes the _________, and then the ___________
Bipolar cells and ganglion cells
The macula is a small region of the _________
retina
What part of the eye does the macula contain?
Fovea
What is the fovea?
Central vision; highest quality vision
The optic disk lacks ____________, making a _______
Photoreceptors; blind spot
The neural layer of the retina contains (3)
Photoreceptors, bipolar cells, ganglion cells
Two types of bipolar cells
On and Off
Horizontal cells
Sculpts activity at the synapse between photoreceptors and bipolar cells
Amacrine cells
Sculpt activities between bipolar cells and ganglion cells
Photoreceptors
Afferent (sensory) neurons that absorb light and change to electrical signals
Two types of photoreceptors
Rods and cones
Photoreceptors contain ___________ in inner/outer segment
Photopigments; outer
Retinal
Light-absorbing molecules; in rods and cones
Opsins
4 proteins that bind retinal and allow different colors to be interpretated
Do rods and cones have the same or different opsins?
Different
Rods are more sensitive to __________, while cones are more responsible for __________ vision
Light; color
Opsins absorb different ____________, which observes ______________
Wavelengths; what we see
What is color vision?
The ability to detect differences in the wavelength of light
Rods are better in ______ light compared to Cones and Rods are meant for ___________________ vision whereas cones are meant for ________ vision
dim; black and white; color
Rods have ___________ opsin and Cones have ___________ opsin
Rhodopsin; small, medium, large
Highest concentration of cones is in the _________
Fovea
Highest concentration of rods in ______________
Periphery
Cones have a _____ spatial resolution
High
CGMP ________ in light
catalyzes
The ligan for opsin is a
photon of light
Do opsins have metabotropic or ionotropic receptors?
Metabotropic receptors
Phosphodiesterase (PDE)
Effector protein that our G-protein transducin activates
cGMP catalyzes and is converted to
GMP
RMP of photoreceptors
-40 mV
Hyperpolarization of photoreceptors
-70 mV
Glutamate is inhibitory in ONLY On/off bipolar cells
ON
On bipolar cells are ____ in the dark and _________ in the light
hyperpolarize, depolarize
Off bipolar cells are ______ in the dark and _______ in the light
Depolarized, hyperpolarized
In the photoreceptors, light activates the _____, which releases ____________, which catalyzes the _____ into _____, closing the ____________, which ______ the cell
opsin; G-Protein; cGMP; GMP; cGMP cation channel; hyperpolarizes
On bipolar cells are active in the ______
light
Off bipolar cells are active in the _______
dark
Process of ON bipolar cells in the dark;
Photoreceptors releasing _____, which ____________, which closes/opens the channel.
Glutamate; activates the g-protein; closes
Are On Bipolar cells in the dark hyperpolarized or depolarized
Hyperpolarized
Process of ON bipolar cells in the light;
Photoreceptors are _________ glutamate, which _________ g-protein, which means that the _____________
not releasing; does not activate; channel is not open
Process of OFF bipolar cells in the dark;
Photoreceptors are _______ glutamate, which activates the metabotropic/ionotropic channels, which ______ the cell
releasing; ionotropic; depolarizes the cell
Process of OFF bipolar cells in the light;
Photoreceptors are ______ glutamate; which activates/does not activate the ionotropic channels, which _______ the cells
Not releasing; does not activate; hyperpolarizes
Photoreceptors in the light __________ glutamate
Release
Photoreceptors in the dark __________ glutamate
Do not release glutamate
In the dark, the ganglion cells are activated by _______
OFF bipolar cells
In the light, the ganglion cells are activated by _________
ON bipolar cells
