& x20;Which sensory receptor generates a hyperpolarizing receptor potential upon stimulation? - INI-CET EXAM -2026

INI-CET EXAM -2026

Applied Physiology

Easy

Appeared in: INI-CET EXAM -2026

Explanation

Visual receptors (rods and cones) are unique among sensory receptors because they hyperpolarize (become more negative) in response to their stimulus, which is light.
This hyperpolarization occurs because light initiates a biochemical cascade that leads to the closing of sodium (Na+) channels.
By stopping the constant inward flow of positive ions (the 'dark current'), while potassium efflux continues, the cell's internal membrane potential becomes more negative.

Option B: Gustatory (taste) receptors depolarize in response to chemical tastants. The binding of tastants opens various cation channels, leading to an influx of positive ions and depolarization.
Option C: Olfactory (smell) receptors depolarize when odorant molecules bind to them. This activates a G-protein pathway that opens sodium and calcium channels, causing an influx of positive ions and depolarization.
Option D: Auditory receptors (hair cells in the cochlea) depolarize in response to sound waves. The mechanical bending of their stereocilia opens potassium (K+) channels, causing an influx of K+ from the surrounding endolymph, which leads to depolarization.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Sensory receptor potential and phototransduction as background academic context rather than a clinical decision trigger.
Understanding photoreceptor hyperpolarization is fundamental for diagnosing and managing retinal diseases like retinitis pigmentosa, where the progressive loss of rods and cones disrupts this process, leading to vision loss.
Certain medications can interfere with ion channels in the retina, potentially causing visual disturbances. A nurse should be aware of these side effects when administering such drugs.
What if? - If a genetic defect prevented the breakdown of cGMP in photoreceptors, the sodium channels would remain open even in the presence of light. The cells would fail to hyperpolarize, leading to a condition like congenital stationary night blindness, as the brain would not receive a signal that light is present.

How to Approach the Question

First, identify the core concept of the question, which is the type of electrical potential change (hyperpolarization vs. depolarization) in sensory receptors.
Recall the general principle that most sensory receptors depolarize (become more positive) upon stimulation to generate a signal.
Remember the key exception to this rule: photoreceptors (visual receptors) in the eye are unique in that they hyperpolarize.
Analyze the options provided. Auditory, gustatory, and olfactory receptors all follow the general rule of depolarization.
Conclude that the visual receptor is the only one listed that hyperpolarizes, making it the correct answer.

Concept Tested & Keywords

Concept Tested: Sensory receptor potential and phototransduction
Stem keywords: sensory receptor, hyperpolarizing receptor potential, stimulation
Lead-in keywords: Which

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