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 can be sent to the brain. Rods produce a response by utilising [[G-proteins|G-proteins]]&nbsp;and the secondary messenger [[CGMP|cGMP]].&nbsp;<ref>Alberts et al, Molecular Biology of the Cell (2008), Fifth Edition, Garland Science, Pages 917-918.</ref>  
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Rods 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;A decrease in [[CGMP|cGMP]].&nbsp;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 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>  
  
 
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Revision as of 14:08, 23 October 2015

Rods 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 A decrease in cGMP. 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 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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