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Questions and Answers
Under which lighting condition does the human iris contract, and what is the approximate diameter of the pupil under average lighting conditions?
Under which lighting condition does the human iris contract, and what is the approximate diameter of the pupil under average lighting conditions?
- Bright light; ≈ 8 mm
- Dim light; ≈ 3 mm
- Dim light; ≈ 4 mm (correct)
- Bright light; ≈ 4 mm
If a person transitions from a brightly lit environment to a dimly lit environment, what change occurs in the iris and pupil?
If a person transitions from a brightly lit environment to a dimly lit environment, what change occurs in the iris and pupil?
- Iris contracts, pupil size decreases.
- Iris relaxes, pupil size decreases.
- Iris contracts, pupil size increases. (correct)
- Iris relaxes, pupil size increases.
Why does the pupil appear black?
Why does the pupil appear black?
- The pupil reflects most of the light that enters eye.
- The pupil transmits all the light that enters the eye.
- The pupil refracts all the light that enters the eye.
- The pupil absorbs almost all the light that enters the eye. (correct)
What is the approximate range of pupil diameter change in response to varying light conditions, from bright to dim?
What is the approximate range of pupil diameter change in response to varying light conditions, from bright to dim?
A person's pupils are measured to be approximately 3 mm in diameter. What is the most likely ambient lighting condition?
A person's pupils are measured to be approximately 3 mm in diameter. What is the most likely ambient lighting condition?
Flashcards
What is the pupil?
What is the pupil?
The opening in the center of the iris through which light enters the eye's lens.
Why is the pupil black?
Why is the pupil black?
Mostly appears black because the light that enters is absorbed inside the eye.
Pupil size in average light
Pupil size in average light
Averages ≈ 4mm in diameter under normal light conditions.
Pupil size range
Pupil size range
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Iris's Response to Light
Iris's Response to Light
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Study Notes
- The pupil is the small opening in the center of the iris
- Light enters the lens through the pupil
- The pupil appears black because almost all light that enters is absorbed inside the eye
- Under average light conditions, the pupil opening is about 4mm
- The pupil's diameter can change from 3mm in bright light to 8mm in dim light
- The physiologic reason for the change in size isn't clear
- In bright light, the iris relaxes
- In dim light, the iris contracts
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Description
The pupil is the opening in the center of the iris that allows light to enter the lens. It appears black because light that enters is absorbed inside the eye. The pupil's diameter changes from 3mm in bright light to 8mm in dim light.
