Which of the following occurs when light hits a photoreceptor?

When light hits a photoreceptor, it initiates a phototransduction cascade that leads to several significant physiological changes within the cell. The initial event is the absorption of photons by photopigments in the outer segments of the photoreceptors, which causes a conformational change in the pigment molecules. This change activates a G-protein called transducin, which then activates phosphodiesterase (PDE).

The activation of PDE results in the hydrolysis of cyclic guanosine monophosphate (cGMP). As cGMP levels decrease, this has crucial effects on the ion channels in the photoreceptor membrane. Normally, cGMP keeps sodium channels open, allowing Na+ ions to flow into the cell, which contributes to the depolarized state of the resting photoreceptor. However, when light activates the phototransduction pathway, the reduction of cGMP leads to the closure of these sodium channels, causing the photoreceptor to hyperpolarize.

In this hyperpolarized state, the release of glutamate, which is the neurotransmitter utilized by photoreceptors to communicate with bipolar cells, decreases significantly. Thus, the physiological outcome of light exposure results in the photoreceptor becoming hyperpolarized,