Fotoretseptorite

Fotoretseptorite, also known as photoreceptors, are specialized cells in the retina of the eye responsible for converting light into electrical signals. These signals are then transmitted to the brain, enabling us to see. There are two main types of photoreceptors: rods and cones.

Rods are highly sensitive to light and are primarily responsible for vision in low-light conditions, or scotopic vision. They do not perceive color and provide monochromatic, or black and white, vision. Humans have approximately 120 million rods, located mainly in the peripheral regions of the retina.

Cones are less sensitive to light than rods and function best in brighter conditions, known as photopic vision. Cones are responsible for color perception and fine detail, or visual acuity. There are three types of cones, each sensitive to different wavelengths of light: red, green, and blue. This allows us to perceive the full spectrum of colors. Humans have about 6 million cones, concentrated in the fovea, the central part of the retina.

When light strikes a photoreceptor, it triggers a biochemical cascade. This process involves a light-sensitive pigment called a photopigment, such as rhodopsin in rods and photopsins in cones. The absorption of light causes a change in the shape of the photopigment, initiating a signal that alters the cell's membrane potential. This electrical signal is then processed and passed on to other neurons in the retina, eventually reaching the optic nerve and the brain for interpretation as vision. The precise functioning and interplay of rods and cones are crucial for our ability to navigate and interact with our visual environment.