Talking about the eye: 1.Ultimately, the activation of transducin causes what ty

Question

Talking about the eye:
1.Ultimately, the activation of transducin causes what type of channel to close in the outer segment, which causes the photoreceptor membrane to ___________, which closes calcium channel in the inner segment, which ultimately stops the release of what signaling molecule?
2. When the signaling molecule in “1” is not released, what happens at a bipolar cell? Talking about the eye:
1.Ultimately, the activation of transducin causes what type of channel to close in the outer segment, which causes the photoreceptor membrane to ___________, which closes calcium channel in the inner segment, which ultimately stops the release of what signaling molecule?
2. When the signaling molecule in “1” is not released, what happens at a bipolar cell? which closes calcium channel in the inner segment, which ultimately stops the release of what signaling molecule?
2. When the signaling molecule in “1” is not released, what happens at a bipolar cell?

Explanation / Answer

1. Depolarise.

Transducin activates PDE which converts cGMP to GMP and cGMP level drops. Without cGMP to bind to them, cGMP gated catiom channels in the outer segment of membrane close preventing k+ amd Ca+2 ions entering the photoreceptor and depolarising it. cGMP gated anion closes calcium channel in inner segment.

The photoreceptor is hyperpolarized to -90mV and this means the volatge gated calcium channels in the end plates of photo receptor remain closed and no neurotransmitter is released from the photoreceptor.

2. Bipolar cells receive inputs from a set of photoreceptor cells which defines the bipolar cells receptive field. The neurotransmitter released from a photoreceptor cell is glutamate. When the signaling molecule 1 is not released, the glutamate is not released from bipolar cells there by the input is not perceived.

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