Sensory Systems part 2

  1. pigment responding to light in vision
    rhodopsin

    - sits in plasma membrane of a photoreceptor cell
  2. metabotropic sensory cells that transform light into action potentials
    photoreceptor cells
  3. part of the eye that protects the eye
    cornea
  4. Light comes in through the __ of the eye & is focused on the __ in the back of the eye
    pupil; fovea centralis (where cones are located)
  5. The __ segment in rod cells have discs of plasma membrane containing __ to capture photons.
    outer; rhodopsin
  6. The rhodopsin molecule consists of __ (a protein) and a light-absorbing group, __
    opsin; 11-cis-retinal
  7. __ absorbs photons of light and changes to the isomer __. __ (a g-protein) then gets activated & the alpha subunit shuttles over to a __, which converts __ to __. As a result, the cation channel will __, causing a more __ voltage
    • 11-cis-retinal;
    • all-trans-retinal
    • Transducin
    • phosphodiesterase (PDE)
    • cGMP
    • GMP
    • close;
    • negative (hyperpolarized)

    (page 54 on slide)
  8. What will happen when transducin is not activated?
    Alpha subunit does not shuttle over to phosphodiesterase, so cGMP stays bound to the cation channel. (cGMP does not convert to GMP). As a result, the cation channel will be open & Na+ & Ca2+ will flow into the cell, creating a more positive (depolarized) voltage.

    (page 54 on slide)
  9. The membrane potential of rod cells is __ in the dark & __ in response to light.
    • depolarized;
    • hyperpolarizes (becomes more negative)
  10. There is __ cGMP levels in the dark, therefore there is a __ glutamate release.
    high; high

    (opposite in light)
  11. Light is __ to the __ where light goes through the axons of the __ cells that form the __ to the __ cells that process incoming signals to the __ where light is absorbed.
    • transmitted;
    • retina;
    • ganglion;
    • optic nerve;
    • bipolar;
    • photoreceptors (rods & cones)

    Any photons not absorbed by the photoreceptors are absorbed by the pigmented epithelium.

    (page 65 on slide)
  12. When light hits a __, light bounces back and blindness occurs.
    non-pigmented epithelium

    ex. Deer
  13. Rate of photoreceptor neurotransmitter release affects rate of release from __ onto __. This determines the rate of action potentials to the __ to the __ then to the occipital lobe.
    • bipolar cells;
    • ganglion cells;
    • optic nerve;
    • thalamus
  14. In the dark, the cone is __ & __ is released to the on-center & off-center bipolar cell.
    • depolarized;
    • high levels of glutamate

    (page 66 on slide)
  15. In response to light, the cone becomes __ & __ is released to the on-center & off-center bipolar cell.
    • hyperpolarized;
    • a decrease in glutamate

    (page 66 on slide)
  16. The on-center bipolar cell has __ receptors
    metabotropic (g-protein coupled)
  17. The off-center bipolar cell has __ receptors
    ionotropic (AMPA)
  18. Both on-center & off-center ganglion cells have __ receptors
    ionotropic
  19. In the dark (cone depolarized), glutamate is released to __ receptors on the off-center bipolar cell, causing the cell to be __ & the transmitter release is __. Firing of the off-center ganglion cell will then be __.
    • ionotropic
    • depolarized (due to positive ions such as Na+ flowing in);
    • increased;
    • increased (due to receiving a lot of glutamate)

    EPSP, threshold, then action potential occurs firing to the optic nerve to the thalamus to the occipital lobe telling the brain that there is lack of light (in the dark).

    (page 66 on slide)
  20. In the dark (cone depolarized), glutamate is released to __ receptors on the on-center bipolar cell, causing the cell to be __ & the transmitter release is __. Firing of the off-center ganglion cell will then be __
    • metabotropic;
    • hyperpolarized;
    • decreased;
    • decreased (due to not getting much glutamate)

    Action potential doesn't occur.

    (page 66 on slide)
  21. In response to light (cone hyperpolarized), there is __ glutamate being released to __ receptors, therefore the off-center cell will be __ & the transmitter release is __. Firing of the off-center ganglion cell will then be __
    • less;
    • ionotropic;
    • hyperpolarized;
    • decreased;
    • decreased

    Action potential doesn't occur.

    (page 66 on slide)
  22. In response to light (cone hyperpolarized), there is __ glutamate being released to __ receptors, therefore the on-center cell will be __ & the transmitter release is increased. Firing of the on-center ganglion cell will then be __
    • less;
    • metabotropic;
    • depolarized (due to lack of inhibition);
    • increased;
    • increased

    EPSP, threshold, then action potential occurs firing to the optic nerve to the thalamus to the occipital lobe telling the brain that there is light.

    (page 66 on slide)
  23. The brain is stimulated to sense light when firing of the __ ganglion cell is increased. The brain is stimulated to sense dark when firing of the __ ganglion cell is increased.
    • on-center;
    • off-center

    (page 66 on slide)
Author
sophathida
ID
325131
Card Set
Sensory Systems part 2
Description
Week 5, Ch. 41
Updated