Retina in eyes acts as a

RRB Staff Nurse Jaipur-6th June 2018

Applied Physiology

Easy

Appeared in: RRB Staff Nurse Jaipur-6th June 2018

Explanation

'Film in the camera' because the retina serves as the light-sensitive layer at the back of the eye.
The retina contains photoreceptor cells (rods and cones) that detect light and convert it into neural signals, which are then sent to the brain for interpretation.
This function is directly analogous to how photographic film or a digital sensor in a camera captures light to form an image.
As stated in physiology textbooks, the eye is optically equivalent to a camera, where the retina corresponds to the film.

Option A: The lens in a camera is analogous to the eye's own crystalline lens, not the retina. Both structures are responsible for focusing light.
Option B: The shutter in a camera, which controls the duration of light exposure, is analogous to the eyelid. The iris and pupil, which control the amount of light, are analogous to the aperture.
Option D: This option is incorrect because a correct and well-established analogy exists between the retina and camera film, as described in option C.

Visual 1: Diagram - A side-by-side comparison showing a cross-section of the human eye next to a cross-section of a camera, with labels pointing to analogous parts (Retina-Film, Lens-Lens, Iris-Aperture).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Analogy between the human eye and a camera, specifically the function of the retina as background academic context rather than a clinical decision trigger.
Understanding the retina's function is fundamental for nurses in ophthalmology and general practice to educate patients about eye health.
Knowledge of retinal function helps in recognizing symptoms of serious conditions like retinal detachment (floaters, flashes of light), macular degeneration (central vision loss), and diabetic retinopathy (vision changes in diabetic patients).
What if? - If a patient presents with sudden 'floaters' and 'flashes of light' in their vision, a nurse should recognize these as potential signs of retinal tear or detachment. The priority action would be to ensure the patient receives an urgent ophthalmologic evaluation, as delaying treatment can lead to permanent vision loss. This is different from the gradual blurring associated with cataracts.

How to Approach the Question

First, identify the key term in the question, which is 'Retina'.
Recall the primary function of the retina in the process of vision. It's the light-sensitive tissue at the back of the eye.
Next, consider the analogy presented: the eye as a camera.
Evaluate each option by comparing the function of the camera part to the function of the retina.
The lens focuses light. The shutter controls exposure time. The film captures the image. The retina captures the image. Therefore, retina is analogous to film.
Select the option that provides the most accurate functional comparison.

Concept Tested & Keywords

Concept Tested: Analogy between the human eye and a camera, specifically the function of the retina.
Stem keywords: Retina, eyes, acts as
Lead-in keywords: BEST, MOST RELEVANT CLUE
Negative lead-in flag: false

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