Anatomy - Vision (Part 2) - Photoreceptor Signaling & Photobleaching

The video tutorial explores the physiology and biochemistry of retinal cells, focusing on photoreceptors. It explains how photoreceptors are hyperpolarized in light, leading to the activation of ganglion cells. The tutorial delves into the structure and function of rhodopsin, a protein complex crucial for light detection. It describes the biochemical processes in darkness and light, including the role of cyclic GMP and sodium channels. The video also covers the photobleaching cycle, emphasizing the importance of vitamin A in regenerating 11-cis retinal. Finally, it sets the stage for the next video, which will discuss how visual signals are transmitted to the brain.

What is the role of bipolar cells in the retina?

• They detect light directly.

• They inhibit ganglion cells.

• They are responsible for color vision.

• They activate photoreceptor cells.

What forms rhodopsin in photoreceptor cells?

• Opsin and cyclic GMP

• Opsin and all-trans retinal

• Opsin and sodium ions

• Opsin and 11-cis retinal

What is necessary for photoreceptor depolarization in the dark?

• Presence of all-trans retinal

• Activation of transducin

• Presence of cyclic GMP

• Closed sodium channels

What is the role of cyclic GMP in the dark?

• It closes sodium channels.

• It activates transducin.

• It keeps sodium channels open.

• It converts opsin to rhodopsin.

What happens to 11-cis retinal when light strikes rhodopsin?

• It activates sodium channels.

• It isomerizes to all-trans retinal.

• It forms a new opsin.

• It becomes cyclic GMP.

What is the function of transducin in the light?

• It opens sodium channels.

• It forms rhodopsin.

• It converts all-trans retinal to 11-cis retinal.

• It activates phosphodiesterase.

What happens to sodium channels in the light?

• They open due to transducin activation.

• They close due to lack of cyclic GMP.

• They remain open.

• They are unaffected by light.

Why is the process of photobleaching important?

• It prevents the formation of rhodopsin.

• It activates transducin.

• It closes sodium channels.

• It regenerates 11-cis retinal.

How does vitamin A contribute to vision?

• It opens sodium channels.

• It is converted to 11-cis retinal.

• It inhibits transducin.

• It directly activates photoreceptors.

What is the consequence of stopping the photobleaching process?

• Permanent activation of ganglion cells

• Increased production of cyclic GMP

• Light blindness due to lack of 11-cis retinal

• Continuous depolarization of photoreceptors