031 How Rods and Cones respond to Light

In this episode, Leslie Samuel explains how rods and cones in the eye respond to light. The video covers the process of light entering the eye, focusing on the retina, and interacting with rhodopsin in rods. It details the biochemical reactions involving rhodopsin, transducin, and phosphodiesterase, leading to changes in membrane potential and neurotransmitter release. The video emphasizes the unique process in rods where light causes a decrease in neurotransmitter release, contrasting with typical depolarization processes.

What is the primary function of the lens in the eye?

• To detect light

• To focus light onto the retina

• To produce tears

• To protect the eye from dust

Which visual pigment is found in rods?

• Melanin

• Chlorophyll

• Rhodopsin

• Opsin

What happens to cis-retinal when it absorbs light?

• It becomes more stable

• It changes to trans-retinal

• It forms a new pigment

• It breaks down into vitamin A

What is the role of transducin in the visual process?

• To produce rhodopsin

• To absorb light

• To activate phosphodiesterase

• To convert light into electrical signals

How does phosphodiesterase contribute to vision?

• By breaking down rhodopsin

• By forming new rods

• By producing light

• By converting cyclic GMP to GMP

What happens to sodium channels in the dark?

• They open

• They close

• They release neurotransmitters

• They become inactive

What is the effect of light on neurotransmitter release in rods?

• Decreases release

• Changes the type of neurotransmitter

• Increases release

• No effect

What is the membrane potential of rods in the absence of light?

• Repolarized

• Neutral

• Hyperpolarized

• Depolarized

What is the role of cyclic GMP in rod cells?

• To produce light

• To convert to rhodopsin

• To open sodium channels

• To close sodium channels

What happens to the membrane potential when light is detected?

• It remains unchanged

• It becomes more positive

• It fluctuates randomly

• It becomes more negative