Question

Type only please

d. The visual transduction system was a challenging molecular cascade to fully elucidate. One of the biggest challenges was that light caused a hyperpolarization of the transmembrane electrical potential whereas for a typical neuron such as a motor neuron a stimulus causes a depolarization with an accompanying action potential. Explain why light causes this hyperpolarization in the rod photoreceptor.

e. The visual transduction system is a marvelous system for several reasons not the least of which includes its ability to adapt to different levels of ambient light. How is this accomplished?

Answer 1

1. A chemical known as glutamate is released to the Bipolar cells when in dark which causes depolarization of the photoreceptors.

The binding of the glutamate to a metabotrophic receptor causes hyperpolarization when in light which then causes depolarization of the bipolar cells leading to less release of the glutamate.

2. The visual system is able to perform its activity because of the retina of the eye which has the ability to adjust in different light situations.

Light adaptation takes place through a process in which the pupil contracts and there is decrease in rhodopsin. These two activities help the eye react in the correct manner with the illumination.

During Dark adaptation the dilatation of pupils takes place, at the same time there are changes in the rods and cones of our retina assisting the pupil's activity.