Chapter 2. Functional Anatomy of the Retina
2.1 Title slide
Demonstration 2.3
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You must read each slide, and complete any questions on the slide, in sequence.
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Functional Anatomy of the Retina
Interact with a depiction of the human retina.
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This micrograph shows a cross section of the retina near the fovea, where some of the cell layers are "pushed to the side" to minimize interference with the image at the fovea.
Courtesy of Dr. Deborah W. Vaughan, Histology Learning System, Boston University
Courtesy of Dr. Deborah W. Vaughan, Histology Learning System, Boston University
What Is the Functional Anatomy of the Retina?
The retina is made up of several different classes of neurons and is structured in layers:
The axons of the RGCs exit the eye at the optic disk, where they form a bundle called the optic nerve.
The fovea, at the center of the retina, is where light from objects at the center of gaze strikes the retina. There are no rods in the fovea, and the density of cones is very high. This contributes to maximizing high-acuity vision at the center of gaze.
Within the retina, the pathways of neural signals can be broadly described as follows:
- The three main layers are called nuclear layers because they contain the nuclei of the various types of retinal neurons:
- The outer nuclear layer consists of the photoreceptors (but not including their inner and outer segments).
- The inner nuclear layer contains bipolar cells, horizontal cells, and amacrine cells.
- The ganglion cell layer consists of retinal ganglion cells (RGCs).
- The nuclear layers are separated by two synaptic layers, where the retinal neurons make synapses with each other:
- The synapses among the photoreceptors, bipolar cells, and horizontal cells are contained in the outer synaptic layer.
- The synapses among the bipolar cells, amacrine cells, and RGCs are contained in the inner synaptic layer.
- Closest to the back of the eye is a layer consisting of the inner and outer segments of the photoreceptors (rods and cones), the retinal neurons that transduce light into neural signals. The "business ends" of the photoreceptors, where transduction occurs, are embedded in a layer of cells called the pigment epithelium, which is itself attached to the choroid.
The axons of the RGCs exit the eye at the optic disk, where they form a bundle called the optic nerve.
The fovea, at the center of the retina, is where light from objects at the center of gaze strikes the retina. There are no rods in the fovea, and the density of cones is very high. This contributes to maximizing high-acuity vision at the center of gaze.
Within the retina, the pathways of neural signals can be broadly described as follows:
- Incoming light strikes the outer parts of the photoreceptors, where it is transduced into neural signals.
- A "through pathway" transmits signals forward from photoreceptors to bipolar cells to RGCs.
- A "lateral pathway" allows the presence of light at one location on the retina to affect the responses of photoreceptors, bipolar cells, and RGCs at adjacent locations on the retina.
- Horizontal cells receive signals from photoreceptors and other horizontal cells and send signals back to photoreceptors and laterally to other horizontal cells.
- Amacrine cells receive signals from bipolar cells and other amacrine cells and send signals back to bipolar cells, laterally to other amacrine cells, and forward to RGCs.
- Retinal ganglion cells receive signals from bipolar cells and amacrine cells and send action potentials to the brain via the optic nerve.
2.2 Explain - dnd
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Drag and drop each label into the correct box on this cross-section of the retina.
2.3 Explain
You must complete the question and then click SUBMIT before you can click proceed to the next screen.
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What Is the Functional Anatomy of the Retina?
The retina is made up of several different classes of neurons and is structured in layers:
- The three main layers are called nuclear layers because they contain the nuclei of the various types of retinal neurons:
- The outer nuclear layer consists of the photoreceptors (but not including their inner and outer segments).
- The inner nuclear layer contains bipolar cells, horizontal cells, and amacrine cells.
- The ganglion cell layer consists of retinal ganglion cells (RGCs).
- The nuclear layers are separated by two synaptic layers, where the retinal neurons make synapses with each other:
- The synapses among the photoreceptors, bipolar cells, and horizontal cells are contained in the outer synaptic layer.
- The synapses among the bipolar cells, amacrine cells, and RGCs are contained in the inner synaptic layer.
- Closest to the back of the eye is a layer consisting of the inner and outer segments of the photoreceptors (rods and cones), the retinal neurons that transduce light
into neural signals. The "business ends" of the photoreceptors, where transduction occurs, are embedded in a layer of cells called the pigment epithelium, which is itself attached to the choroid.
The axons of the RGCs exit the eye at the optic disk, where they form a bundle called the optic nerve.
The fovea, at the center of the retina, is where light from objects at the center of gaze strikes the retina. There are no rods in the fovea, and the density of cones is very high. This contributes to maximizing high-acuity vision at the center of gaze.
Within the retina, the pathways of neural signals can be broadly described as follows:
The axons of the RGCs exit the eye at the optic disk, where they form a bundle called the optic nerve.
The fovea, at the center of the retina, is where light from objects at the center of gaze strikes the retina. There are no rods in the fovea, and the density of cones is very high. This contributes to maximizing high-acuity vision at the center of gaze.
Within the retina, the pathways of neural signals can be broadly described as follows:
- Incoming light strikes the outer parts of the photoreceptors, where it is transduced into neural signals.
- A "through pathway" transmits signals forward from photoreceptors to bipolar cells to RGCs.
- A "lateral pathway" allows the presence of light at one location on the retina to affect the responses of photoreceptors, bipolar cells, and RGCs at adjacent locations on the retina.
- Horizontal cells receive signals from photoreceptors and other horizontal cells and send signals back to photoreceptors and laterally to other horizontal cells.
- Amacrine cells receive signals from bipolar cells and other amacrine cells and send signals back to bipolar cells, laterally to other amacrine cells, and forward to RGCs.
- Retinal ganglion cells receive signals from bipolar cells and amacrine cells and send action potentials to the brain via the optic nerve.
2.4 Test - dnd
You must complete the question and then click SUBMIT before you can click proceed to the next screen.
test_dnd
Drag each label on the left to connect to the correct description on the right. When you're finished,
click SUBMIT.
2.5 Test - dnd
You must complete the question and then click SUBMIT before you can click proceed to the next screen.
test_dnd_replace
Drag the correct cell types into the blank boxes next to the matching descriptions. When you're finished, click SUBMIT.
2.6 Explain
You must complete the question and then click SUBMIT before you can proceed to the next screen.
activity_2_3_slide_6
Click on the arrows to rotate the cross-sections of the retina so each is oriented in the appropriate direction. Assume that the eye containing the retina is looking toward the outside light. When you have finished positioning both cross-sections click 'Submit' to submit your answer and get feedback.