Rod photoreceptors are roughly how many times more sensitive than cones?

Rod photoreceptors are roughly how many times more sensitive than cones?

• A. 10 times
• B. 100 times
• C. 1000 times
• D. 10000 times

Answer: (C)

Rods are far more sensitive to light than cones. In very dim conditions, the rod system can detect single photons, while cones typically need many photons to trigger a response. This enormous sensitivity comes from strong amplification in the rod phototransduction cascade and from having more photopigment per cell, plus longer outer segments that capture more light. All told, rods are about a thousand times more sensitive than cones, which is why they drive vision in low light (scotopic) while cones handle brighter light and color.

Rods are far more sensitive to light than cones. In very dim conditions, the rod system can detect single photons, while cones typically need many photons to trigger a response. This enormous sensitivity comes from strong amplification in the rod phototransduction cascade and from having more photopigment per cell, plus longer outer segments that capture more light. All told, rods are about a thousand times more sensitive than cones, which is why they drive vision in low light (scotopic) while cones handle brighter light and color.