Podcast
Questions and Answers
What is the primary reason the rod cells release neurotransmitter in complete darkness?
What is the primary reason the rod cells release neurotransmitter in complete darkness?
- The Na$^+$ pump is continuously pumping out Na$^+. (correct)
- Light hits the retina, stimulating cones.
- The Na$^+$ channels are closed.
- Rhodopsin is inactive.
What occurs in rod cells when light hits the retina?
What occurs in rod cells when light hits the retina?
- Hyperpolarisation reduces neurotransmitter release. (correct)
- Trans-retinal activates rhodopsin to open Na$^+$ channels.
- Bipolar cells are inhibited, preventing action potentials.
- Na$^+$ channels open to allow depolarisation.
During dark adaptation, what happens to rhodopsin as the eyes adjust to darkness?
During dark adaptation, what happens to rhodopsin as the eyes adjust to darkness?
- It continuously produces trans-retinal.
- All rods adapt in less than 10 minutes.
- It becomes less sensitive to light.
- Cis-retinal accumulates, increasing sensitivity. (correct)
How does the content of neurotransmitter release from rod cells change in response to light?
How does the content of neurotransmitter release from rod cells change in response to light?
Which process explains the changing permeability of the rod cell membrane during dark adaptation?
Which process explains the changing permeability of the rod cell membrane during dark adaptation?
What is the effect of the bipolar neuron when it receives decreased neurotransmitter from the rod in dim light?
What is the effect of the bipolar neuron when it receives decreased neurotransmitter from the rod in dim light?
What is the consequence of neurotransmitter release at the synapse between the rod cell and bipolar cell in complete darkness?
What is the consequence of neurotransmitter release at the synapse between the rod cell and bipolar cell in complete darkness?
What happens to the Na$^+$ channels in rods when they are bleached during light exposure?
What happens to the Na$^+$ channels in rods when they are bleached during light exposure?
What is the role of retinal in the composition of rhodopsin?
What is the role of retinal in the composition of rhodopsin?
What occurs to rhodopsin when it is exposed to bright light?
What occurs to rhodopsin when it is exposed to bright light?
What is the isomerization process of retinal when light is involved?
What is the isomerization process of retinal when light is involved?
How long does it take for trans-retinal to be converted back to cis-retinal?
How long does it take for trans-retinal to be converted back to cis-retinal?
What happens to rods in bright light conditions?
What happens to rods in bright light conditions?
Which statement correctly describes the relationship between opsin and retinal in rhodopsin?
Which statement correctly describes the relationship between opsin and retinal in rhodopsin?
What is the result of the bleaching process in rhodopsin?
What is the result of the bleaching process in rhodopsin?
Which structural change occurs in rhodopsin upon absorbing a photon of light?
Which structural change occurs in rhodopsin upon absorbing a photon of light?
Flashcards
Rhodopsin
Rhodopsin
A conjugated protein found in rods of the retina that absorbs light and initiates the process of phototransduction.
Retinal
Retinal
A light-absorbing carotenoid molecule derived from vitamin A that's part of rhodopsin.
Opsin
Opsin
The protein component of rhodopsin.
Photoisomerization
Photoisomerization
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Bleaching
Bleaching
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Photosensitivity
Photosensitivity
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Rhodopsin Regeneration
Rhodopsin Regeneration
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Dark Adaptation
Dark Adaptation
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Hyperpolarization of the Rod
Hyperpolarization of the Rod
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Inhibitory Synapse
Inhibitory Synapse
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Excitatory Synapse
Excitatory Synapse
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Depolarization of the Rod
Depolarization of the Rod
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Rod Cell Depolarization in Darkness
Rod Cell Depolarization in Darkness
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Rod Cell Hyperpolarization in Light
Rod Cell Hyperpolarization in Light
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Study Notes
Mechanism of Photoreception
- Rods contain the pigment rhodopsin
- Rhodopsin is formed by the combination of:
- A light-absorbing carotenoid molecule called retinal (retine)
- A protein called opsin
- Retinal exists in two isomeric forms:
- cis form (in dark)
- trans form (in light)
- When a rod cell is exposed to light, light causes the retinal molecule to change from its cis form into a trans form
- This change puts strain on the molecule and the bond between retinal and opsin is broken
- This causes the rod cell to bleach
- enzymes convert trans-retinal to the original cis-retinal in the dark
- This process takes a few minutes
- In dim light, rhodopsin is bleached
- In bright light, rhodopsin is bleached, and rods lose their photosensitivity
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