Which cells of the retina are responsible for detecting light in low light conditions?
Group of answer choices
Bipolar
Rods
Cones
Ganglion
The correct answer and explanation is:
The correct answer is Rods.
Rods are specialized photoreceptor cells in the retina that are responsible for detecting light in low-light conditions, or scotopic vision. Unlike cones, which are responsible for color vision and operate best in bright light (photopic vision), rods are highly sensitive to light but cannot detect color. They are concentrated in the peripheral regions of the retina and function best in dim light, making them essential for night vision.
Rods contain a photopigment called rhodopsin, which is very sensitive to light. In low-light environments, rhodopsin undergoes a chemical change when it absorbs photons, triggering an electrical signal that is sent to the brain via the optic nerve. This process enables the brain to interpret the image formed in low-light conditions. However, because rods do not detect color, they contribute only to grayscale vision in dim light.
The cones, on the other hand, are responsible for color vision and are most active in bright light. They are concentrated in the central part of the retina, particularly in the fovea, which is the region responsible for sharp central vision. Cones operate under conditions of high light intensity, and their three types (red, green, and blue cones) are sensitive to different wavelengths of light, enabling color vision.
Bipolar cells and ganglion cells do not directly detect light. Bipolar cells act as intermediaries, transmitting signals from photoreceptors (rods and cones) to ganglion cells. Ganglion cells receive input from bipolar cells and send the visual information to the brain for processing. Thus, the responsibility for detecting light in low-light conditions lies specifically with the rods.