Rods and cones

Definition

Rods and cones are photoreceptor cells in the retina of the eye responsible for vision. Rods are sensitive to low light levels and do not perceive color, while cones detect color and function best in bright light.

5 Must Know Facts For Your Next Test

1. Rods are more numerous than cones, with approximately 120 million rods compared to 6 million cones in the human retina.
2. Rods are highly sensitive to light, making them essential for night vision.
3. Cones are concentrated in the fovea, the central part of the retina, which is crucial for high-acuity vision.
4. There are three types of cones: S-cones (short-wavelength), M-cones (medium-wavelength), and L-cones (long-wavelength), each sensitive to different wavelengths of light corresponding to blue, green, and red colors respectively.
5. The absence or malfunction of certain types of cones can lead to color blindness.

Review Questions

Related terms

Retina:

The light-sensitive layer at the back of the eye that contains rods and cones.

Fovea:

A small depression in the retina where visual acuity is highest due to a high concentration of cones.

Photopigments: Light-sensitive molecules found in rods and cones that trigger chemical changes leading to visual perception.