Rhodopsin and the correlation to Retinitis Pigmentosa.
In order to understand exactly how Rhodopsin, a photoreceptor found in retinal rods play a role in the disease Retinitis Pigmentosa, it is essential to understand the structure and function of the eye. The human eye rays of light get focused by the lens of the eye and the cornea, and form a clear image in the retina. Photoreceptors that capture photons of light come in two different structures, rods and cones. Rods are responsible for vision in poor lighting, and cones are responsible for vision in bright light. Rhodopsin is a type of photoreceptor found in rods, and its main purpose is to capture light photons and allow for vision. .
Figure 1. A cross-section of the human eye.
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Rhodopsins are complexes formed by the binding of retinaldehyde, the oxidized form of retinol, to the protein opsin. The complex undergoes a series of complex reactions in response to visible light, mainly through the use of neurotransmitters, which are released by the hyper-polarization and depolarization of the eye cells. These nerve impulses are then sent to the brain. .
Retinitis Pigmentosa is the name given to a group of eye diseases that are often characterized by night blindness and the gradual loss of peripheral vision. RP causes visual loss, and may lead to eventual blindness by affecting the light sensitive receptors in the retina. This genetic disease affects over nearly four million people across the world and many Australians. RP can other wise be characterized as a form of retinal degenerations. .
There has been much research, both proposed, and completed that questions a possible relationship between mutated Rhodopsins, and the onset of RP. Rhodopsin mutations, or mutations in the opsin gene, have been found to account for nearly a quarter of all cases of autosomal dominant RP. In 1989, researchers in Ireland found that the locations of the mutation that caused RP, was very close to, or perhaps within the rhodopsin gene.
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