PSB 3002 Exam #2 Questions and
Answers
Layers of the retina, starting with the deepest. - ANSWER-i. Photoreceptive layer;
deepest (contains rods & cones)
ii. Bipolar cell layer
iii. Ganglion cell layer
How are the layers of the retina connected? - ANSWER-Synaptic connections with
photoreceptors
What cells comprise the retina from deepest to shallowest? - ANSWER-Horizontal
cells (Between photoreceptors and bipolar layer)
Bipolar cells
Amacrine cells (Between bipolar and ganglion layer)
Ganglion cells
What are photoreceptors? - ANSWER-This is a type of receptor responds to
electromagnetic radiation (light) to allow vision. These are rods and cones
Cones: Where are they located, how many are there and what 2 types of vision is it?
- ANSWER-Located in the fovea
i. 6 million
ii. Daytime vision
iii. High acuity (Sharpness)
iv. Color vision
Rods: Where are they located, how many are there, and when is it used? -
ANSWER-Located peripheral to the fovea
i. 120 million
ii. Used in dim lighting
What is the blind spot of the eye? - ANSWER-The optic disc
(where the optic nerve exits)
Photopigments: Where are they located, what are they comprised of, what is one
photopigment and what is it made of? - ANSWER-i. In membrane of lamellae (outer
segment of photoreceptors)
ii. Comprised of opsin and retinal
iii. Rhodopsin: Made out of rod opsin and retinal.
What is a receptive field? - ANSWER-A receptive field is the region on the retina in
which stimuli will activate a neuron. It contains the photoreceptors where light is
received and sent to bipolar and ganglion cells.
, What is the difference between receptive fields for rods vs. cones? Central vs
peripheral vision, location, how many rods/cones vs ganglion cells, and how
accurate is each vision. - ANSWER-Cones -
-Central vision
-Located in the fovea (center of retina)
-Equal numbers of ganglion cells and cones so they can receive one-on-one
connections.
-Very precise
(better for precise vision in light)
Rods -
-Peripheral vision
-Located around the fovea
-Many rods per single ganglion. (Many more rods than ganglions)
-Less precise
(better for dark vision like looking at night stars)
What is transduction? - ANSWER-Process by which environmental energy is
converted to a change in membrane potential
What is a receptor potential? - ANSWER-Change in sensory receptor membrane
potential
When are photoreceptors depolarized and when are they hyperolarized? -
ANSWER-In the dark, photoreceptors are depolarized.
Light splits Rhodopsin and hyperpolarizes photoreceptor
What determines how much glutamate is released in the bipolar cells? - ANSWER-
Depolarization = more glutamate in the synapse with bipolar cells
Hyperpolarization = Less glutamate released.
How do receptive fields work for cats? - ANSWER-Has on center and off center cells
but also has a third set of cells called on/off cells.
On/off cells respond to both light and darkness.
How does the visual field connect to the retina? - ANSWER-Axons from the ganglion
cells connect to the inner nasal part of the retina. Left ganglion to left retina and right
ganglion to right retina.
How does the retina connect to the lateral geniculate nuclei in the thalamus? -
ANSWER-The retina is connected to the LGN and criss-cross.
Right field of vision (inner right eye and outer left eye) goes to the left half of the LGN
which leads to the primary visual cortex.
Opposite for the left field of vision
What is the optic chiasm? - ANSWER-The X-shaped structure formed at the point
below the brain where the two optic nerves cross over each other.
Answers
Layers of the retina, starting with the deepest. - ANSWER-i. Photoreceptive layer;
deepest (contains rods & cones)
ii. Bipolar cell layer
iii. Ganglion cell layer
How are the layers of the retina connected? - ANSWER-Synaptic connections with
photoreceptors
What cells comprise the retina from deepest to shallowest? - ANSWER-Horizontal
cells (Between photoreceptors and bipolar layer)
Bipolar cells
Amacrine cells (Between bipolar and ganglion layer)
Ganglion cells
What are photoreceptors? - ANSWER-This is a type of receptor responds to
electromagnetic radiation (light) to allow vision. These are rods and cones
Cones: Where are they located, how many are there and what 2 types of vision is it?
- ANSWER-Located in the fovea
i. 6 million
ii. Daytime vision
iii. High acuity (Sharpness)
iv. Color vision
Rods: Where are they located, how many are there, and when is it used? -
ANSWER-Located peripheral to the fovea
i. 120 million
ii. Used in dim lighting
What is the blind spot of the eye? - ANSWER-The optic disc
(where the optic nerve exits)
Photopigments: Where are they located, what are they comprised of, what is one
photopigment and what is it made of? - ANSWER-i. In membrane of lamellae (outer
segment of photoreceptors)
ii. Comprised of opsin and retinal
iii. Rhodopsin: Made out of rod opsin and retinal.
What is a receptive field? - ANSWER-A receptive field is the region on the retina in
which stimuli will activate a neuron. It contains the photoreceptors where light is
received and sent to bipolar and ganglion cells.
, What is the difference between receptive fields for rods vs. cones? Central vs
peripheral vision, location, how many rods/cones vs ganglion cells, and how
accurate is each vision. - ANSWER-Cones -
-Central vision
-Located in the fovea (center of retina)
-Equal numbers of ganglion cells and cones so they can receive one-on-one
connections.
-Very precise
(better for precise vision in light)
Rods -
-Peripheral vision
-Located around the fovea
-Many rods per single ganglion. (Many more rods than ganglions)
-Less precise
(better for dark vision like looking at night stars)
What is transduction? - ANSWER-Process by which environmental energy is
converted to a change in membrane potential
What is a receptor potential? - ANSWER-Change in sensory receptor membrane
potential
When are photoreceptors depolarized and when are they hyperolarized? -
ANSWER-In the dark, photoreceptors are depolarized.
Light splits Rhodopsin and hyperpolarizes photoreceptor
What determines how much glutamate is released in the bipolar cells? - ANSWER-
Depolarization = more glutamate in the synapse with bipolar cells
Hyperpolarization = Less glutamate released.
How do receptive fields work for cats? - ANSWER-Has on center and off center cells
but also has a third set of cells called on/off cells.
On/off cells respond to both light and darkness.
How does the visual field connect to the retina? - ANSWER-Axons from the ganglion
cells connect to the inner nasal part of the retina. Left ganglion to left retina and right
ganglion to right retina.
How does the retina connect to the lateral geniculate nuclei in the thalamus? -
ANSWER-The retina is connected to the LGN and criss-cross.
Right field of vision (inner right eye and outer left eye) goes to the left half of the LGN
which leads to the primary visual cortex.
Opposite for the left field of vision
What is the optic chiasm? - ANSWER-The X-shaped structure formed at the point
below the brain where the two optic nerves cross over each other.
