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 &nbsp;transduction light signals into chemical signals which can be sent to the brain. Rods produce a response by utilising G-proteins&nbsp;and the secondary messenger cyclic GMP.&nbsp;<ref>Alberts et al, Molecular Biology of the Cell (2008), Fifth Edition, Garland Science, Pages 917-918.</ref>  
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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>  
  
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=== References ===
 
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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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