Light Transduction + Receptive Field

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Quizzes Created: 24 | Total Attempts: 15,395
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  • 1/12 Questions

    In the dark, photoreceptors release NTs continuously

    • True
    • False
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About This Quiz

Explore the mechanisms of light transduction and receptive fields in this engaging quiz. Understand what makes photoreceptors unique, the behavior of rods and cones, and how photoreceptors operate in different lighting conditions. Perfect for students in neuroscience or visual sciences.

Light Transduction + Receptive Field - Quiz

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  • 2. 

    Rods follow the stimulus change closely, whereas cones have a latency in their response.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Latency of response for rods is longer- rise time and fall time are longer- and then membrane changes slower in rods whereas cone response follows the stimulus change more closely

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  • 3. 

    When a photon of light strikes Rhodopsin, phosphodiesterase (PDE) becomes:

    • Active

    • Inactive

    Correct Answer
    A. Active
    Explanation
    When a photon of light strikes Rhodopsin, it causes a conformational change in the molecule. This conformational change activates phosphodiesterase (PDE). Therefore, the correct answer is "active".

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  • 4. 

    The definition of a receptive field is only applied to ganglion cells.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    can be applied to any visual neuron: PR, BP, GC, H, A

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  • 5. 

    What is the purpose of cGMP in photorecptors?

    • Closes Na channels

    • Keeps Na channels open

    • Inhibits PDE

    • Regenerates Rho

    Correct Answer
    A. Keeps Na channels open
    Explanation
    Decreasing the cGMP in the cytosol results in the CLOSURE of the Na channels when light is around

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  • 6. 

    What is the voltage potential inside a photoreceptor in the dark? What is it in presence of light?

    • -60mV; -20mV

    • -20mV; -50mV

    • -20mV; -60mV

    • -50mV; -20mV

    Correct Answer
    A. -20mV; -60mV
    Explanation
    In the light, the Na channels in the OS are closed and therefore the Na that's being pumped out of the IS cannot get back into the PR. Since Na is + charged, there will be a decrease in the membrane potential (more negative) when light is present vs in the dark.

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  • 7. 

    In the dark, Na channels are closed, preventing Na to enter the OS.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    In the dark, Na channels are open and Na flows into the OS. Light results in a closure of the Na channels so that Na doesn't flow back into the OS.

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  • 8. 

    As part of the dark current, Na is continuously pumped out of the OS and follows it's concentration gradient and enters the photoreceptor in the IS

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Opposite is true. Na pumped out of IS and then follows gradient to flow back into the PR through the OS.

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  • 9. 

    What makes photoreceptors unique?

    • Only have membrane potential changes

    • Hyperpolarize when excited

    • Decrease NT release when excited

    • 2 of the above

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    Photoreceptors are unique because they exhibit all of the mentioned characteristics. They only have membrane potential changes, meaning that their response to light stimuli is solely based on changes in their membrane potential. Additionally, they hyperpolarize when excited, which means that their membrane potential becomes more negative. Lastly, they decrease neurotransmitter (NT) release when excited, indicating that their response to light leads to a reduction in the release of neurotransmitters. Therefore, all of the above statements accurately describe the unique features of photoreceptors.

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  • 10. 

    Active PDE results DIRECTLY in conversion of:

    • GMP --> cGMP

    • Rho -->ospin + all trans retinal

    • CGMP --> GMP

    • Rho --> active Rho

    Correct Answer
    A. CGMP --> GMP
    Explanation
    This results in a decrease in the cGMP concentration in the cytosol of the PR because it has been converted into GMP

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  • 11. 

    Light needs to be present during the entire time that Rho is being transformed into opsin and all-trans retinal

    • True

    • False

    Correct Answer
    A. False
    Explanation
    (I'm not sure that I've articulated this question very well...but check out pg. 161 picture for more clarification)

    The only thing that the absorption of light does to Rho is convert it to Beta-Rho. All other changes occur at normal body temperature.

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  • 12. 

    What is Hartline's definition of a receptive field?

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  • Current Version
  • Jan 24, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • May 13, 2011
    Quiz Created by
    Tseemore
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