Photoreceptors
Photoreceptors
Photoreceptors (/ˌfoʊtoʊrɪˈsɛptərz/; from the Greek φῶς, phōs, "light" and Latin receptor, "receiver") are specialized types of neurons found in the retina of the eye that are capable of phototransduction. The primary function of photoreceptors is to convert light into electrical signals, which are then processed by the brain to form visual images.
There are two main types of photoreceptors: rod cells and cone cells. Rod cells are more sensitive to light and allow for vision in low light conditions, while cone cells are responsible for color vision and function best in well-lit conditions.
Etymology
The term "photoreceptor" is derived from the Greek word "phōs" meaning "light" and the Latin word "receptor" meaning "receiver". This term accurately describes the function of these cells, which is to receive light and convert it into electrical signals.
Function
Photoreceptors are responsible for the initial step in the visual process, which is the conversion of light into electrical signals. This process, known as phototransduction, involves a series of chemical reactions that are triggered by the absorption of light by a pigment molecule in the photoreceptor cell.
The electrical signals generated by photoreceptors are then transmitted to other neurons in the retina, which process the signals and send them to the brain via the optic nerve. The brain interprets these signals to form visual images.
Related Terms
- Phototransduction: The process by which light is converted into electrical signals in the photoreceptor cells of the retina.
- Rod cells: A type of photoreceptor cell in the retina that is highly sensitive to light and allows for vision in low light conditions.
- Cone cells: A type of photoreceptor cell in the retina that is responsible for color vision and functions best in well-lit conditions.
- Retina: The light-sensitive layer of tissue at the back of the inner eye that contains the photoreceptor cells.
- Neuron: A specialized cell that transmits nerve impulses; neurons in the retina process the electrical signals generated by photoreceptors and transmit them to the brain.
External links
- Medical encyclopedia article on Photoreceptors
- Wikipedia's article - Photoreceptors
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