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Eye Anatomy in Dim Light

• Diagram B Representation

  • Illustrates the view of the eye under dim light conditions.

  • Structures depicted may include the cornea, pupil, lens, retina, and rods/cones.

Changes in the Eye in Dim Light

• Pupil Dilation

  • In response to low light, the pupil dilates to allow more light in.

• Rod Activation

  • The retina contains photoreceptor cells: rods (for low light) and cones (for color vision).

  • In dim light, rods are the primary receptors utilized.

  • They become more sensitive, enhancing vision in low-light scenarios.

• Retinal Changes

  • The composition of photopigments in rods alters, changing how they react to light.

  • More photopigments are used up in the dark (bleaching) and replenished as light enters the eye.

Importance of Changes

• Visual Adaptation

  • Necessary for functioning in varying lighting conditions, allows for survival: an ability to see in the dark can aid in avoiding predators.

• Energy Conversion Process

  • When light rays cross the eyeball, they are absorbed by cells (specifically photoreceptors) in the retina.

  • The light energy is converted to electrical energy.

  • This electrical energy becomes a nerve impulse.

  • The nerve impulse in the rod cells travels along a sensory nerve.

  • This nerve links the eye to the brain.

  • The signal is interpreted as an image by the brain, allowing visual perception.

Sentence Completion

• Complete sentences with correct terminology:

  • When light rays cross the eyeball they are absorbed by cells in the retina.

  • The light energy is converted to electrical energy.

  • This becomes an electrical signal.

  • Energy in the rod travels along a sensory nerve.

  • This nerve links the eye to the brain.

  • An electrical signal is interpreted as an image.