Valgusevastuvõtvad

Valgusevastuvõtvad, also known as photoreceptors, are specialized cells in the retinas of eyes that are responsible for converting light into electrical signals. These signals are then transmitted to the brain, where they are interpreted as vision. There are two main types of photoreceptor cells in the human retina: rods and cones.

Rods are highly sensitive to light and are primarily responsible for vision in low-light conditions, a process known as scotopic vision. They are more numerous than cones and are distributed more widely across the retina, particularly in the peripheral areas. Rods do not detect color, which is why our color vision is significantly reduced in dim light.

Cones, on the other hand, function best in bright light and are responsible for color vision and sharp detail, a process known as photopic vision. There are three types of cones, each sensitive to different wavelengths of light: red, green, and blue. The combination of signals from these cone types allows us to perceive the full spectrum of colors. Cones are concentrated in the fovea, the central part of the retina, which is responsible for our sharpest vision.

Both rods and cones contain photopigment molecules that undergo chemical changes when exposed to light. This light-induced chemical reaction triggers a cascade of events that ultimately leads to the generation of an electrical signal. This intricate process is fundamental to our ability to see.