Retina Structure and Phototransduction Quiz

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What envelops the unmyelinated RGC axons in the nerve fibre layer?

Extensions of Müller’s cells and astrocytes

Where do the RGC axons travel after reaching the nerve fibre layer?

Towards the optic disc and then in the optic nerve

What is the current focus of retinal prosthesis development mentioned in the text?

Further developments in animal models with migration of retinal cells into the perforated sub-retinal implant

How many types of cones contribute to trichromatic color vision?

3 types Signup and view all the answers

What is the role of visual pigments in the absorption of light?

They mediate the absorption of light by cones Signup and view all the answers

What is the effect of cyclic nucleotides in vision?

Modulate the response to light Signup and view all the answers

What percentage of cones are S-cones in the foveal pit, and what is their maximum density on the foveal slope?

3-5% in the foveal pit, and 15% on the foveal slope Signup and view all the answers

How do the spectral range of light and age-related changes in the lens affect colour perception?

The spectral range of light reaching the retina affects colour perception, and age-related yellowing of the lens can alter this range. Signup and view all the answers

How do humans and mantis shrimp differ in their colour vision abilities?

Humans have 3 types of cones, distinguishing colours that differ by 5 nm, while mantis shrimp have 12 types, distinguishing colours that differ by 25 nm. Signup and view all the answers

What is the significance of the relative ratios of different types of cones in colour sensitivity?

The relative ratios of different types of cones determine colour sensitivity, with S-cones, M-cones, and L-cones contributing differently to colour perception. Signup and view all the answers

What is the main difference between the processing of signals from cones in the retina and the brain?

The retina processes signals from cones, while the brain interprets these signals to create our perception of colour. Signup and view all the answers

What is the recommended reading resource for learning more about retinal circuits and colour vision?

WebVision, specifically the chapter on retinal circuits. Signup and view all the answers

Explain the process of phototransduction in photoreceptors when light activates Rhodopsin.

Light activates Rhodopsin which in turn activates Transducin, leading to the activation of PDE, degradation of cGMP, closure of cGMP-gated channels, and hyperpolarization of the plasma membrane. Signup and view all the answers

What is the role of cyclic nucleotides in the phototransduction process in photoreceptors?

Cyclic nucleotides, such as cGMP, play a crucial role in opening or closing ion channels in response to light, ultimately affecting the polarization of the plasma membrane. Signup and view all the answers

Describe the neurotransmitters involved in retinal neurons and their functions.

Retinal neurons use neurotransmitters such as glutamate and GABA to transmit signals. Glutamate acts as an excitatory neurotransmitter in some pathways and an inhibitory neurotransmitter in others. Signup and view all the answers

Explain the role of horizontal cells in the retina.

Horizontal cells mediate lateral interactions in the outer retina, playing a crucial role in processing visual information and modulating signals between photoreceptors and bipolar cells. Signup and view all the answers

How does the activation of rhodopsin pathway lead to the hyperpolarization of the photoreceptor plasma membrane?

Activation of Rhodopsin triggers a cascade of events involving Transducin and PDE which results in the closure of cGMP-gated channels, decreasing Na+ and Ca2+ influx, leading to hyperpolarization of the membrane. Signup and view all the answers

Discuss the role of gap junctions in the signaling between photoreceptors and interneurons.

Gap junctions facilitate direct electrical communication between photoreceptors, bipolar cells, and horizontal cells in the retina, influencing signal integration and synchronization. Signup and view all the answers

What are the types of bipolar cells found in the retina and how do they differ in their synaptic connections?

Bipolar cells in the retina include rod bipolar cells, S-cone bipolars, midget bipolars, and diffuse bipolars, each with distinct synaptic connections to photoreceptors and ganglion cells. Signup and view all the answers

How do bipolar cells process signals from photoreceptors into responses to light?

Bipolar cells receive input from photoreceptors and modulate their responses based on the type of photoreceptor and the conditions of light, either hyperpolarizing or depolarizing in response to specific stimuli. Signup and view all the answers

Explain the structural components of the phototransduction cascade in cones and how they differ from rods.

Cones have a unique structural organization in the phototransduction cascade, with distinct synaptic connections, including pedicles and triads, compared to the spherule and ribbons found in rod phototransduction. Signup and view all the answers

What is the significance of neurotransmitter release inhibition in photoreceptors during phototransduction?

Inhibition of neurotransmitter release, such as glutamate, in photoreceptors plays a crucial role in signal transmission and modulation, contributing to the precision and efficiency of visual processing in the retina. Signup and view all the answers