How do rods differ from cones in function?

Rods are responsible for vision in low light conditions, while cones are responsible for colour and detailed vision.

Rods and cones are two types of photoreceptor cells found in the retina of the eye. They are named for their distinctive shapes, with rods being long and narrow, and cones being short and wide. These cells are responsible for converting light into electrical signals that can be processed by the brain, but they do so in different ways and under different conditions.

Rods are incredibly sensitive to light and allow us to see in conditions that are less than perfectly lit. They are most effective in dim light or at night, which is why our vision in these conditions is often less sharp and less colourful. This is because rods do not perceive colour and instead focus on providing us with a general outline of our surroundings. They are more numerous than cones, with about 120 million rods in the human eye.

On the other hand, cones are responsible for our ability to see colour and fine detail. They function best in bright light conditions. There are three types of cones, each sensitive to a different range of wavelengths corresponding to red, green, and blue light. By comparing the signals from these different types of cones, our brain can construct a full-colour image of the world. There are about 6 million cones in the human eye, and they are most densely packed in the centre of the retina, an area known as the fovea.

In summary, rods and cones each play a crucial role in our vision. Rods allow us to see in low light conditions, providing a broad outline of our surroundings, while cones enable us to perceive colour and fine detail in bright light.