Human Anatomy and Physiology : Help with Visual Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #1 : Help With Visual Physiology

Which of the following describes the function of rod cells in vision?

Possible Answers:

 Circular shapes

Fine detail, which is why they are located at the fovea centralis

Vibrant colors

Peripheral motion, especially in low light situations

Angles

Correct answer:

Peripheral motion, especially in low light situations

Explanation:

Rods are located in every part of the retina except the fovea centralis, which is where the cones that allow us to see most colors and detail are located. Rods are responsible for our peripheral vision, and are very sensitive to motion. Rods do not provide very good spatial differentiation, but their sensitivity to light is essential to providing definition.

Example Question #1 : Sensory Organs

The ciliary muscle is responsible for which function in the eye?

Possible Answers:

Moving the eyeball left and right

Closing the eyelid

Varying the size of the pupil

The shaping of the lens

Opening the eyelid

Correct answer:

The shaping of the lens

Explanation:

The ciliary muscle surrounds the lens in a circular fashion. When contracted, the ciliary muscle will decrease in size, which allows the lens to become more convex in shape. This allows the eye to focus on closer objects.

The iris, or pupillary sphincter, is capable of constricting and dilating the pupil. The main muscle responsible for raising the eyelid is the levator palpebrae superioris. The orbicularis oculi is responsible for closing the eyelid.

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