Ocular Anatomy and Physiology TS1

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What is the purpose of phosphorylation in the phototransduction cascade?

To amplify the signal

To activate rhodopsin

To inactivate rhodopsin (correct)

To reform cGMP

What is the result of the decrease in intracellular cGMP in photoreceptors?

Increase in glutamate release

Activation of transducin

Opening of CNG channels

Closure of CNG channels (correct)

What is the role of transducin in the phototransduction cascade?

To activate rhodopsin

To activate phosphodiesterase 6 (correct)

To hydrolyze cGMP

To release glutamate

What is the effect of light on rhodopsin?

It causes rhodopsin to change into metarhodopsin II Signup and view all the answers

What is the purpose of guanylyl cyclase in the recovery phase of the phototransduction cascade?

To reform cGMP Signup and view all the answers

What is the conformational change in the chromophore of rhodopsin upon photon absorption?

From 11-cis-retinal to 11-trans-retinal Signup and view all the answers

What is the primary function of phosphodiesterase 6 (PDE6) in the phototransduction cascade?

To hydrolyze cGMP to 5'-GMP Signup and view all the answers

What is the role of arrestin in the phototransduction cascade?

To inactivate rhodopsin Signup and view all the answers

What is the effect of lower intracellular Ca2+ levels in the recovery phase?

Activation of guanylyl cyclase Signup and view all the answers

What is the result of the activation of several hundred transducin molecules by metarhodopsin II?

Amplification of the signal by guanosine triphosphate (GTP) Signup and view all the answers

What is the primary function of the retinal pigment epithelium (RPE)?

To nourish and collect waste products from the photoreceptor layer Signup and view all the answers

What is the structure that provides the highest visual acuity?

Fovea centralis Signup and view all the answers

What is the approximate number of cones in the human retina?

6 million Signup and view all the answers

What is the purpose of the Henle's fiber layer in the retina?

To process signals from foveal and parafoveal photoreceptors Signup and view all the answers

What is the function of the inner segment of photoreceptor cells?

To synthesize components for outer segment renewal Signup and view all the answers