Rod photoreceptors

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 Rods are photoreceptors found in the retinas of vertebrates and are involved in non colour vision. Rods are highly specialised cells and permit vision in low light via the  transduction light signals into chemical signals which van be sent to the brain. Rods produce a response by utilising
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Rod photoreceptors (cells) are highly specialised, extended cells, that permit vision at low light levels because of the disc filled outer segment. Within the discs is a vast amount of rhodopsin. This visual pigment absorbs dim light best at a wavelength of 495nm. Once the light is received by rhodopsin, the signal is transduced into chemical signals via [[G-proteins|G-proteins]]&nbsp; and a decrease in [[CGMP|cGMP]]&nbsp; that causes a knock on closure of sodium channels whilst the potassium ions continue to flow out of the cell. The cell membrane now becomes hyperpolarized to -70mv. Therefore, the number of glutamate neurotransmitters released from the rod cell decreases. Rod cells go on to produce a response in the nerve signal pathways to the Optic Nerve via a bipolar and ganglion cell. Rod cells get bleached in high intensities of light.<ref>Alberts et al, Molecular Biology of the Cell (2008), Fifth Edition, Garland Science, Pages 917-918.</ref><br>
<gallery>G-protein</gallery>
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and the secondary messenger cyclic GMP.&nbsp;
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=== References  ===
<ref>Alberts et al, Molecular Biology of the Cell, Fifth Edition, Garland Science, 917-918.</ref>
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<references />

Latest revision as of 09:35, 27 October 2015

Rod photoreceptors (cells) are highly specialised, extended cells, that permit vision at low light levels because of the disc filled outer segment. Within the discs is a vast amount of rhodopsin. This visual pigment absorbs dim light best at a wavelength of 495nm. Once the light is received by rhodopsin, the signal is transduced into chemical signals via G-proteins  and a decrease in cGMP  that causes a knock on closure of sodium channels whilst the potassium ions continue to flow out of the cell. The cell membrane now becomes hyperpolarized to -70mv. Therefore, the number of glutamate neurotransmitters released from the rod cell decreases. Rod cells go on to produce a response in the nerve signal pathways to the Optic Nerve via a bipolar and ganglion cell. Rod cells get bleached in high intensities of light.[1]

References

  1. Alberts et al, Molecular Biology of the Cell (2008), Fifth Edition, Garland Science, Pages 917-918.
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