Vision and Photoreceptors Quiz
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Questions and Answers

What causes the blind spot to disappear when you look directly at it?

  • The eye adjusts to the darkness.
  • The light source is too close to the eye.
  • The blood vessels move with the eye.
  • The brain fills in the missing information from the surrounding area. (correct)

The vascular tree seen using the penlight technique is actually a reflection of blood vessels within the eye.

True (A)

What is the name of the neural structure in the eye where transduction takes place?

retina

The motion of the ______ makes the shadows of the blood vessels move, allowing us to see them.

<p>penlight</p> Signup and view all the answers

Match the following terms with their descriptions.

<p>Blind spot = The area on the retina where the optic nerve exits the eye, lacking photoreceptor cells. Transduction = The process of converting light energy into electrical signals in the retina. Fundus = The inner lining of the eye, containing the retina, choroid, and sclera. Vascular tree = The network of blood vessels visible in the eye when the shadow of blood vessels is cast by a moving light source.</p> Signup and view all the answers

Visual pigments are made in the ______ segment of the photoreceptor.

<p>inner</p> Signup and view all the answers

The synapse of a photoreceptor is located at the outer segment.

<p>False (B)</p> Signup and view all the answers

What are the two main components of a visual pigment molecule?

<p>Opsin and chromophore</p> Signup and view all the answers

Which of these statements correctly describes the function of the chromophore?

<p>It captures photons of light. (A)</p> Signup and view all the answers

Match the following terms with their correct descriptions:

<p>rhodopsin = The visual pigment found in rods. melanopsin = A photopigment sensitive to ambient light. photoactivation = The activation of a visual pigment by light. hyperpolarization = A change in membrane potential where the inner membrane surface becomes more negative.</p> Signup and view all the answers

All four types of visual pigments are found in each photoreceptor.

<p>False (B)</p> Signup and view all the answers

The chromophore known as Retinal is derived from ______, which is synthesized from beta-carotene.

<p>vitamin A</p> Signup and view all the answers

What is the primary role of the outer segment of a photoreceptor?

<p>To contain and utilize visual pigments for light detection.</p> Signup and view all the answers

What is the primary function of bipolar cells in relation to cones?

<p>They transmit graded potentials from cones. (D)</p> Signup and view all the answers

S-cones are the most abundant type of cone in the fovea.

<p>False (B)</p> Signup and view all the answers

What are the three types of cone photopigments mentioned?

<p>S-cones, M-cones, L-cones</p> Signup and view all the answers

The foveal center is essentially missing from the ______ cone population.

<p>S</p> Signup and view all the answers

Match the following cone types with their respective color sensitivities:

<p>S-cones = Short-wavelength sensitivity M-cones = Medium-wavelength sensitivity L-cones = Long-wavelength sensitivity</p> Signup and view all the answers

What is the area in the retina called where the optic nerve exits and results in a blind spot?

<p>Optic disc (D)</p> Signup and view all the answers

The cornea has a rich supply of blood vessels to help maintain its transparency.

<p>False (B)</p> Signup and view all the answers

What role does the tear film play in relation to the cornea?

<p>It provides a smooth, clear surface, protects, lubricates the eyes, and washes away dust.</p> Signup and view all the answers

The absence of __________ at the optic disc results in a blind spot.

<p>photoreceptors</p> Signup and view all the answers

What is one of the components of the eye that helps in focusing light onto the retina?

<p>Lens (D)</p> Signup and view all the answers

The ciliary muscle relaxes when the eye focuses on nearby objects.

<p>False (B)</p> Signup and view all the answers

How quickly does the outer layer of the cornea typically heal if scratched?

<p>Within 24 hours (B)</p> Signup and view all the answers

What is the role of the zonules of Zinn in the eye?

<p>They help hold the lens in place and assist in adjusting its shape.</p> Signup and view all the answers

The cornea's sensory nerve endings are only for the purpose of sight.

<p>False (B)</p> Signup and view all the answers

The refractive power of the eye's optical components must be perfectly matched to the length of the _______.

<p>eyeball</p> Signup and view all the answers

What happens when the cornea is scratched?

<p>It becomes painful and may result in tearing to protect the eye.</p> Signup and view all the answers

Which optical component of the eye is primarily responsible for most of the eye's refractive power?

<p>Cornea (A)</p> Signup and view all the answers

Match the following functions to their corresponding components of the eye:

<p>Cornea = Transparent surface for light entry Tear film = Moisturizes and protects the eye Optic disc = Location of the blind spot Sensory nerve endings = Trigger eye reflexes like tearing</p> Signup and view all the answers

The focal length of the eye changes depending on whether it is focusing on distant or nearby objects.

<p>True (A)</p> Signup and view all the answers

What happens to the lens when a distant object is viewed?

<p>The lens becomes unaccommodated or flatter.</p> Signup and view all the answers

Match the following components of the eye with their functions:

<p>Ciliary muscle = Contracts to focus on near objects Zonules of Zinn = Holds the lens in position Cornea = Provides most refractive power Lens = Adjusts its shape for focusing</p> Signup and view all the answers

What effect does lowering the concentration of calcium have on neurotransmitter release in the synapse?

<p>Decreases neurotransmitter release (B)</p> Signup and view all the answers

Photoreceptors respond in an all-or-nothing fashion.

<p>False (B)</p> Signup and view all the answers

What neurotransmitter is specifically mentioned as being released in the photoreceptor-bipolar cell synapse?

<p>glutamate</p> Signup and view all the answers

The amount of glutamate present in the photoreceptor-bipolar cell synapse is __________ to the number of photons being absorbed by the photoreceptor.

<p>inversely proportional</p> Signup and view all the answers

Match the following elements with their descriptions:

<p>Rhodopsin = Visual pigment in rods Glutamate = Neurotransmitter in synapse Calcium concentration = Regulates neurotransmitter release Photoreceptors = Respond to light stimuli</p> Signup and view all the answers

Which type of cells communicates with photoreceptors?

<p>Bipolar cells (C)</p> Signup and view all the answers

The entire sequence of events in phototransduction takes only a matter of seconds.

<p>False (B)</p> Signup and view all the answers

How do cone visual pigment molecules act in relation to rhodopsin?

<p>Qualitatively similar</p> Signup and view all the answers

Flashcards

Optic Disc

The point where the optic nerve leaves the eyeball, creating a blind spot due to the absence of photoreceptors.

Cornea

The transparent outer layer of the eye that helps focus light.

Cornea Structure

A highly ordered arrangement of fibers in the cornea that makes it transparent.

Cornea's Sensory Nerves

The cornea's rich supply of nerve endings that sense pain, prompting the eye to close in response to irritants.

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Cornea Regeneration

The cornea's ability to regenerate quickly after scratches.

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Tear Film

A thin film of tears covering the cornea that helps protect and lubricate the eye.

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Tears and Eye Protection

Tears help wash away potential contaminants and prevent eye infections.

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Role of Tears

Tears provide a smooth and clear surface, and protect the eye from dryness and infections.

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Cross-modal facilitation

The ability of one sensory modality to influence the perception of another modality, like when sound improves visual perception.

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Accommodation

The process of adjusting the eye's lens shape to focus on objects at different distances.

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Ciliary muscle

The muscle that changes the shape of the eye's lens to focus on objects at different distances.

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Zonules of Zinn

Tiny, thread-like ligaments that connect the ciliary muscle to the lens.

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Unaccommodated lens

A state where the lens is relaxed and focused on distant objects.

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Accommodated lens

A state where the lens is contracted and focused on near objects.

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Lens

The transparent, convex structure within the eye that helps focus light onto the retina.

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Retina

The light-sensitive lining at the back of the eye that converts light into electrical signals.

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Visual Pigment

A light-catching molecule found in photoreceptor cells.

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Rhodopsin

A type of visual pigment found in rod photoreceptor cells.

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Melanopsin

A type of visual pigment sensitive to ambient light, found in a specific type of photoreceptor cell.

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Rod

A photoreceptor cell responsible for low-light vision.

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Chromophore

The part of a visual pigment that captures light photons.

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Hyperpolarization

A change in membrane potential where the inside of the cell becomes more negative relative to the outside.

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Graded Potential

An electrical potential that varies in amplitude depending on the strength of the stimulus.

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What is a Blind Spot?

A small, naturally occurring area in the retina where the optic nerve leaves the eye, resulting in a lack of light-sensitive cells and therefore vision.

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What is Visual Filling-In?

The process by which our brains fill in missing information in our visual field, like in the blind spot, to create a seamless visual experience.

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What are Retinal Blood Vessels?

The tiny blood vessels that supply oxygen and nutrients to the eye's retina, which can be visualized using a simple trick.

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How to Visualize Retinal Blood Vessels?

The technique of using a penlight to visualize your retinal blood vessels by casting shadows that move with the light's motion.

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What is the Retina?

The part of the eye that converts light into electrical signals that the brain can interpret as vision.

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Phototransduction

The process by which light energy is converted into a signal that the brain can understand.

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Photoreceptor Signal

The decrease in the concentration of a neurotransmitter (glutamate) released from photoreceptor cells when light is absorbed.

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Graded Response

A change in the release of glutamate from photoreceptor cells in response to different light intensities.

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Inverse Relationship

The release of fewer glutamate molecules indicates the absorption of more light, leading to a decrease in the signal transmitted to the brain.

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Cone Phototransduction

The process by which cone cells respond to light and contribute to color vision.

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Phototransduction Speed

The rapid sequence of events that occurs within milliseconds after light absorption by a photoreceptor cell.

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Photoreceptor Response

Photoreceptor cells do not respond in an all-or-nothing manner, instead their response is graded based on the intensity of light absorbed.

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Cone cells

Photoreceptor cells in the retina that respond to different wavelengths of light, allowing us to perceive color.

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Fovea

The center of the retina where the density of cone cells is highest, resulting in sharpest visual acuity.

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Uneven Cone Distribution

The distribution of cone cells, particularly short wavelength-sensitive cones, is not equal across the retina, with the fovea lacking these cones.

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Fovea's Color Sensitivity

The fovea centralis contains almost exclusively cone cells, making central vision predominantly color-sensitive.

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Foveal Dichromacy

The fovea is dichromatic, meaning it lacks short wavelength-sensitive cones, explaining its limited blue perception in the central field.

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Study Notes

Chapter 2: The First Steps in Vision: From Light to Neural Signals

  • Vision is a complex process.
  • Light is electromagnetic energy.
  • Light can be absorbed, scattered, reflected, transmitted, or refracted.
  • Light travels in waves or as photons.
  • Light interacts with matter depending on the type of matter and the wavelengths.
  • The eye has a specialized structure to capture and focus light.
  • The eye has different parts: cornea, aqueous humor, lens, pupil, iris, vitreous humor, retina.
  • The cornea is a transparent layer at the front of the eye.
  • The aqueous humor is a watery fluid in the anterior chamber.
  • The lens changes shape to focus light on the retina.
  • The pupil is a dark circular opening at the center of the iris, which allows light into the eye.
  • The iris controls how much light enters the eye.
  • The vitreous humor is a transparent gel-like fluid in the posterior chamber of the eye.
  • The retina is a light-sensitive tissue at the back of the eye.
  • Rods and cones are photoreceptors that respond to specific wavelengths of light.
  • Rods are important for night vision and for detecting low levels of light.
  • Cones are important for color vision, sharpness, and high levels of light.

Dark and Light Adaptation

  • The visual system adjusts to different light levels.
  • Pupil dilation regulates light entering the eye.
  • Photoreceptor regeneration adjusts to light levels over time.
  • The retina contains both rods and cones.

Retinal Information Processing

  • Light activates photoreceptors (rods and cones)
  • Photoreceptors send signals to bipolar cells.
  • Bipolar cells communicate with amacrine and ganglion cells.
  • Ganglion cells send signals to the brain.
  • The retina has a horizontal pathway for lateral inhibition (amacrine and horizontal cells)
  • The retina has a vertical pathway through bipolar and ganglion cells.
  • Ganglion cells have receptive fields that respond to specific regions of light.

Refractive Errors

  • Problems of refraction include emmetropia, myopia, hyperopia, and astigmatism.
  • Emmetropia: No refractive error (normal vision)
  • Myopia: Nearsightedness (light focused in front of retina)
  • Hyperopia: Farsightedness (light focused behind retina)
  • Astigmatism: Unequal curving of refractive surfaces (blurry vision)

Camera Analogy for the Eye

  • F-stop is pupil size
  • Focus is adjusting lenses
  • Film is retina

Visual Angle Measurement

  • Visual angle measures the size of an object, based on its size and distance from observer.
  • The visual angle is how large an object looks on the retina of the eye rather than its actual size.

Types of Ganglion Cells

  • P cells: High visual acuity, important in color vision and shape processing.
  • M cells: Excellent in motion detection, but poor in acuity and color processing.

Intrinsically Photosensitive Retinal Ganglion Cells

  • ipRGCs respond to light, are the first to mature, and don't require input from rods or cones.
  • They help regulate circadian rhythms.

New Retinal Prostheses

  • These devices aim to replace or improve damaged photoreceptors, using implanted electrodes.

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Related Documents

SP – Chapter 2 and Lecture 3 PDF

Description

Test your knowledge on the anatomy and function of the eye, particularly focusing on photoreceptors and visual pigments. This quiz covers key concepts such as the blind spot, neural structures involved in vision, and the components of visual pigments. Perfect for students studying biology or anatomy.

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