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Questions and Answers
Primate eyes have specialized structures for good daylight vision and are able to discriminate ______ and fine details.
Primate eyes have specialized structures for good daylight vision and are able to discriminate ______ and fine details.
color
Rods are generally used for ______ vision, while cones are used for daylight, bright-colored vision.
Rods are generally used for ______ vision, while cones are used for daylight, bright-colored vision.
low-light
The fovea is a tremendously ______-rich spot that is devoid of rods where images focus.
The fovea is a tremendously ______-rich spot that is devoid of rods where images focus.
cone
Most fish, frog, turtle, and bird retinas have three to five types of ______, contributing to excellent color vision.
Most fish, frog, turtle, and bird retinas have three to five types of ______, contributing to excellent color vision.
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Light rays must pass through the entire retina before reaching pigment molecules to excite the ______.
Light rays must pass through the entire retina before reaching pigment molecules to excite the ______.
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The peripheral parts of the retina are sensitive and can detect the slightest glimmer of ______ at night.
The peripheral parts of the retina are sensitive and can detect the slightest glimmer of ______ at night.
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Primates have what is called a duplex retina, allowing good visual discrimination in all ______ conditions.
Primates have what is called a duplex retina, allowing good visual discrimination in all ______ conditions.
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The retina is a filmy piece of tissue, barely half a millimeter thick, that lines the inside of the ______.
The retina is a filmy piece of tissue, barely half a millimeter thick, that lines the inside of the ______.
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The tissue develops from a pouch of the embryonic ______, and the retina is therefore considered part of the brain.
The tissue develops from a pouch of the embryonic ______, and the retina is therefore considered part of the brain.
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Retinal molecules change their conformation in response to ______, or packets of light.
Retinal molecules change their conformation in response to ______, or packets of light.
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The pigment granules in the retina are full of ______, which help absorb stray photons.
The pigment granules in the retina are full of ______, which help absorb stray photons.
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Many mammalian retinas have a preponderance of ______ which are more sensitive to light than cones.
Many mammalian retinas have a preponderance of ______ which are more sensitive to light than cones.
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Nonmammals like turtles have a long, horizontal strip of specialized cells called a visual ______.
Nonmammals like turtles have a long, horizontal strip of specialized cells called a visual ______.
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Photoreceptors transmit information to ______ cells using the molecule glutamate.
Photoreceptors transmit information to ______ cells using the molecule glutamate.
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Some bipolar cells fire in response to glutamate, whereas others ______ firing.
Some bipolar cells fire in response to glutamate, whereas others ______ firing.
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ON bipolar cells have a ______ receptive field.
ON bipolar cells have a ______ receptive field.
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ON-center ganglion cells are activated when a spot of light falls in the center of their ______.
ON-center ganglion cells are activated when a spot of light falls in the center of their ______.
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Photoreceptors stop releasing glutamate when stimulated by ______.
Photoreceptors stop releasing glutamate when stimulated by ______.
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OFF-center ganglion cells react in the opposite way: Their activity increases when the periphery of their ______ is lit.
OFF-center ganglion cells react in the opposite way: Their activity increases when the periphery of their ______ is lit.
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The inner plexiform layer contains about 22 or more different types of ______ cells.
The inner plexiform layer contains about 22 or more different types of ______ cells.
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When light falls on the center of the field, the activity of OFF-center ganglion cells ______.
When light falls on the center of the field, the activity of OFF-center ganglion cells ______.
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Cajal divided the inner plexiform layer into ______ strata.
Cajal divided the inner plexiform layer into ______ strata.
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ON-center ganglion cells are ______ when light falls on the field’s periphery.
ON-center ganglion cells are ______ when light falls on the field’s periphery.
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The major output of the retina to the visual centers in the brain comes from two types of ______ cells.
The major output of the retina to the visual centers in the brain comes from two types of ______ cells.
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Horizontal cells modulate the responses of photoreceptors and ______ cells.
Horizontal cells modulate the responses of photoreceptors and ______ cells.
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This system is polarized into two types: ON center and ______ center ganglion cells.
This system is polarized into two types: ON center and ______ center ganglion cells.
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The visual response is derived from the distinct behavior of ON-center and OFF-center ______ cells.
The visual response is derived from the distinct behavior of ON-center and OFF-center ______ cells.
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Both types of ganglion cells contribute to the brain's processing of ______ information.
Both types of ganglion cells contribute to the brain's processing of ______ information.
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A previously unknown ______ cell type appears to function as a giant photoreceptor itself.
A previously unknown ______ cell type appears to function as a giant photoreceptor itself.
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This ganglion’s cell membrane contains light-reactive molecules known as ______.
This ganglion’s cell membrane contains light-reactive molecules known as ______.
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Many amacrine cells are electrically coupled by ______, creating a massive sheet of cells.
Many amacrine cells are electrically coupled by ______, creating a massive sheet of cells.
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The substances include peptides and the more familiar ______.
The substances include peptides and the more familiar ______.
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The effective field of influence of the AII cells makes them significant in ______ conditions.
The effective field of influence of the AII cells makes them significant in ______ conditions.
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Another wide-field amacrine cell releases ______ in bright light conditions.
Another wide-field amacrine cell releases ______ in bright light conditions.
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The rod-system amacrine cells have less significance in ______ conditions.
The rod-system amacrine cells have less significance in ______ conditions.
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The mechanisms in the retina suggest that there may still be much more to ______.
The mechanisms in the retina suggest that there may still be much more to ______.
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Serotonin, dopamine, and ______ are neurotransmitters discussed in retinal circuitry.
Serotonin, dopamine, and ______ are neurotransmitters discussed in retinal circuitry.
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______ cells are identified as releasing neuro-modulators.
______ cells are identified as releasing neuro-modulators.
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The release of neurotransmitters is thought to influence neurons even at a distance by ______.
The release of neurotransmitters is thought to influence neurons even at a distance by ______.
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The retina is remarkably complex and plays an active role in ______.
The retina is remarkably complex and plays an active role in ______.
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Peptides, nicotine, and muscarine are examples of receptors found on ______ cells.
Peptides, nicotine, and muscarine are examples of receptors found on ______ cells.
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The large-field rod pathway influences the narrow-field ______ pathways.
The large-field rod pathway influences the narrow-field ______ pathways.
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Neuro-modulators are not active at conventional ______.
Neuro-modulators are not active at conventional ______.
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Vision research indicates that the retina is involved in an increasingly active role in the ______ system.
Vision research indicates that the retina is involved in an increasingly active role in the ______ system.
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Study Notes
Retina Structure and Function
- The retina is a thin tissue lining the inside of the eyeball, considered part of the brain
- It's a three-layered structure with nerve cells arranged in rows, separated by synaptic layers
- It contains sensory neurons for light and complex neural circuits for initial image processing
- Image information travels down the optic nerve to the brain for further processing
Photoreceptor Structure and Function
- Photoreceptors (rods and cones) are located at the back of the retina
- Light must pass through the entire retina to reach photoreceptor pigment molecules
- Pigment epithelium is important because it contains retinal, a molecule crucial in vision
- Retinal changes conformation in response to light, which is then recycled back into the pigment epithelium
- Melanin granules absorb stray light, preventing image blurring
Design Variations Based on Lifestyle
- Vertebrate eyes contain rods and cones, serving respectively for low-light and daylight/color vision
- Adaptations vary among species based on their environmental needs and lifestyles
- Rod-dominant retinas are common in nocturnal animals, providing sensitivity in dim light
- Cones are prevalent in animals active in bright light, enabling color vision in detail
- Primates have a duplex retina, balancing color and night vision
Retina Processing
- The retina processes images by separating parts, a step before conveying the information to the brain
- ON and OFF pathways are fundamental to seeing, processing contrast between images and backgrounds
- Horizontal cells process signals from many cones to enhance image details to the bipolar cells
- Amacrine cells further process the information, which leads to clearer boundaries and edges
- Rods and cones rely on different pathways for processing signals, impacting the response time to changes
Amacrine Cells
- Amacrine cells process information in the inner plexiform layer
- They are divided into those containing glycine and those containing GABA
- Amacrine cells help in enhancing image details
- Rod-based visual systems rely on amacrine cells and are critical for dim light conditions
- These cells modulate vision based on lighting conditions
Ganglion Cells
- The ganglion cells receive information from bipolar cells
- Two main types of ganglion cells are ON-center and OFF-center, and they transmit messages via electrical signaling.
- Both types of cells have a central receptive region.
- Ganglion cells are crucial for encoding the visual information to be sent to the brain.
Specialized Visual Regions
- The fovea, a highly concentrated cone region in the primate retina, is optimized for sharp central vision and detail
- Specialized visual streaks are found in some animals' retinas, allowing for the detection of fast-moving objects.
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Description
Test your knowledge on the structure and function of the retina, including photoreceptors and neural circuits. Explore the role of sensory neurons in processing visual information and how design variations affect vision. This quiz dives deep into the complexities of the eye's anatomy.
