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Special cells in the eye’s retina that are responsible for converting light into signals that are sent to the brain. Photoreceptors give us our color vision and night vision. There are two types of photoreceptor cells: rods and cones. A number of eye problems can involve photoreceptor cells. These problems include:
Cone diameter is roughly 2.5 μm in the fovea and rapidly increases outside fovea to 10 μm in periphery. Rod diameter is roughly 3 μm at a field angle of 18° and increases in size to 5.5 μm in periphery. The central 200 μm of the retina is free of rods. The total number of cones in the retina is 6.4 million. There are roughly 125 million rods in the retina. Citation: J. Schwiegerling, Field Guide to Visual and Ophthalmic Optics, SPIE Press, Bellingham, WA (2004). View SPIE terms of use. Excerpt from
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Photoreceptors are specialized cells that are found in the retina of the eye. The structure and function of photoreceptors are so specialized that they have the ability to perform under different conditions. The receptors of the eye are extremely specialized neuroepithelial cells. This is because the cells have both epithelial and neurological functions which make them capable of visual phot transduction. These photoreceptors are biologically important as they have the ability to convert the light which is from the visible electromagnetic radiation into the signals that can stimulate the biological processes. Receptors of EyeThere are three types of photoreceptor cells found in mammalian cells. They are rods, cones and intrinsically photosensitive retinal ganglion cells. Of these, the well-known and classic photoreceptors are rods and cones. Both the receptors of the eye contribute to the information which is used by the visual system to form the representation of the visual world which forms the sight. These photoreceptors are usually typically arranged in an irregular manner. Even though irregular the arrangement is an approximate hexagon which is known as retinal mosaic. The human retina is known to contain 120 million rod cells and 6 million cone cells. All the types of photoreceptors are known to contain pigments that make the cells specialized for the visualization of the image. The photoreceptor cells are very tightly packed which allows them to attain high photopigment density because of which a large number of photoreceptors are able to absorb large amounts of light photons. This leads to better image processing by the brain. There are differences in-between the rods and cones of different species of organisms. The structure and function of photoreceptors allow them to be connected to a network of biological pathways as is observed in the case of invertebrates, and vertebrates although they might be morphologically different and differently packed. Structure and Function of PhotoreceptorsThe mechanism by which the photoreceptors function in light detection through the eyes is defined is known as photoreception. As per this mechanism the light is absorbed by the specialized cells known as photoreceptors which convert the light stimulus into nerve impulses. As already mentioned that there are primarily two types of photoreceptors - rod cells and cones cells. To understand better the structure and function of photoreceptors - the rod cells and cones cells a diagram is given below: [Image will be Uploaded Soon] Given Below is the Function of Rod and Cone Cells and Their Characteristics: Rod Cells
Cone Cells
ConclusionThus, from the given information the main function of rod and cone cells is clear which can be simply stated as - rods are responsible for night-time vision and the cones are responsible for day-time vision. Want to read offline? download full PDF here Download full PDF Is this page helpful? Recently Updated Pages Recently Updated Pages What is the function of the photoreceptors in the retina quizlet?What are the functions of photoreceptors. are specialized neurons found in the retina that convert light into electrical signals that stimulate physiological processes.
What is the function of the retina and what photoreceptors does it contain?The retina is a layer of photoreceptors cells and glial cells within the eye that captures incoming photons and transmits them along neuronal pathways as both electrical and chemical signals for the brain to perceive a visual picture.
What is the function of the rod photoreceptors?Rods are cylindrical shaped photoreceptors. They are more numerous than cone cells, with an estimated 92 million rod cells located in the human retina. They function best in low intensity light (scotopic) and are thus responsible for vision in dimly lit surroundings, such as at dusk.
What is the function of each kind of photoreceptor?There are two types of photoreceptors: cone photoreceptors and rod photoreceptors. These cells function by sensing light and/or color and delivering the message back to the brain through the optic nerve. While cone photoreceptors detect color through bright light, rod photoreceptors are sensitive to low-light levels.
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