Photorezeptorzellen

Photorezeptorzellen are specialized cells in the retina of the eye 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: rods and cones.

Rods are highly sensitive to light and are crucial for vision in low-light conditions, often referred to as scotopic vision. They do not distinguish between colors, which is why our color perception is limited at night. Each retina contains approximately 120 million rods.

Cones are less sensitive to light than rods but are responsible for color vision and sharp detail, known as photopic vision. There are three types of cones, each sensitive to different wavelengths of light: red, green, and blue. This differential sensitivity allows us to perceive a wide spectrum of colors. Cones are concentrated in the fovea, the central part of the retina responsible for sharpest vision. Humans have about 6 million cones.

Both rods and cones contain photopigments, molecules that undergo a chemical change when they absorb light. In rods, this pigment is rhodopsin, while cones contain photopsins. This light-induced chemical cascade triggers a change in the cell's electrical state, initiating the process of visual signal transduction.