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Unit 4: Lesson 1

Foundations of behavior passages

Sight (vision) - Passage 2


The phototransduction cascade is responsible for converting light rays into neural impulses. This cascade occurs within the rods and cones of the retina, and a diagram of the cascade is shown below:
Retinal is essential to this cascade, and is synthesized from vitamin A, which is found in certain foods like carrots. The cascade begins with light converting 11-cis retinal to all-trans retinal:
This activates transducin, leading to the activation of cGMP phosphodiesterase, the hydrolyzation of cGMP, and the closing of cGMP dependent Ca++/Na+ channels.
If the cGMP-dependent Na+ channels involved in the phototransduction cascade were open in the absence of cGMP, what would occur if light was shined into the retina?
Choose 1 answer:
Choose 1 answer: