In the human eye, two structures that are sensitive to light are the retina and the photoreceptor cells within the retina. These structures play essential roles in the process of vision. Retina: The retina is a thin, light-sensitive layer of tissue located at the back of the eye, lining the inner surface of the eyeball. It contains various types of cells, including photoreceptor cells, that are responsible for capturing and processing visual information. The retina acts like the “film” in a camera, capturing incoming light and converting it into electrical signals that are sent to the brain for interpretation. Photoreceptor Cells: Within the retina, there are two main types of photoreceptor cells: Rods: Rod cells are highly sensitive to dim light and are responsible for allowing us to see in low-light conditions, such as at night. They are primarily responsible for black-and-white vision and do not differentiate colors. Cones: Cone cells are responsible for color vision and are sensitive to different wavelengths of light, allowing us to perceive a range of colors. There are three types of cone cells, each sensitive to a specific range of wavelengths (red, green, and blue). The combination of signals from these cone types enables us to see a full spectrum of colors. When light enters the eye and reaches the retina, it interacts with these photoreceptor cells. Rods and cones convert the light into electrical signals, which are then transmitted through a complex network of neurons in the retina before being sent as visual signals to the brain via the optic nerve. The brain processes these signals, allowing us to perceive and interpret the visual world around us.