Anything which evokes a response in the organism is called the?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

A stimulus is formally defined as a change in the environment that evokes a response from a living cell or organism.
This concept is the foundation of the Stimulus-Response (S-R) model in both physiology and behavioral psychology.
Stimuli are detected by sensory receptors, which convert the environmental change into a nerve impulse, initiating a response.
Examples include physical stimuli (like touch or light), chemical stimuli (like taste or smell), and electrical stimuli.

Option A: The word 'Thing' is too general and lacks the precise scientific meaning required. In science, specific terminology is used to avoid ambiguity.
Option B: A 'Situation' refers to the overall context or a set of circumstances. While a situation contains many potential stimuli, it is not the specific agent that directly causes the response.
Option D: 'Incidence' is a term used in epidemiology and public health. It refers to the rate of new occurrences of a disease or condition in a population over time.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition of Stimulus as background academic context rather than a clinical decision trigger.
Understanding the stimulus-response mechanism is crucial for nurses when assessing a patient's neurological status, such as checking reflexes (e.g., pupillary response to light, deep tendon reflexes).
In patient care, nurses often manipulate stimuli to achieve desired responses, such as using calming sounds (auditory stimulus) to reduce anxiety or applying pressure (tactile stimulus) to control bleeding.
What if? If a patient shows no response to a painful stimulus (like a pinprick), it indicates a severe neurological deficit, requiring immediate medical intervention. A normal response would be withdrawal from the stimulus.

How to Approach the Question

First, analyze the question stem to identify the core concept. The key phrase is 'evokes a response in the organism'.
This is a definition-based question. Your task is to find the scientific term that matches this definition.
Evaluate each option against the definition.
Option A ('Thing') is too general. Option B ('Situation') is the context, not the trigger. Option D ('Incidence') is from a different field (epidemiology).
Option C ('Stimulus') directly matches the definition of something that causes a response.
Therefore, select the most precise and scientifically accurate term.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 1 p. 108-109

Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.