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In physiology, a stimulus [1] is a change in a living thing's internal or external environment. This change can be detected by an organism or organ using sensitivity, and leads to a physiological reaction. [ 2 ]
A stimulus is something that causes a physiological response. It may refer to: Stimulation. Stimulus (physiology), something external that influences an activity; Stimulus (psychology), a concept in behaviorism and perception; Stimulus (economics) For government spending as stimulus, see Fiscal policy
Stimulation, in general, refers to how organisms perceive incoming stimuli. As such it is part of the stimulus-response mechanism. Simple organisms broadly react in three ways to stimulation: too little stimulation causes them to stagnate, too much to die from stress or inability to adapt, and a medium amount causes them to adapt and grow as they overcome it.
The stimulus is automatically decreased in steps of a set percentage until the response falls below the target (generation of an action potential). Thereafter, the stimulus is stepped up or down depending on whether the previous response was lesser or greater than the target response until a resting (or control) threshold has been established.
This occurs when a muscle's motor unit is stimulated by multiple impulses at a sufficiently high frequency. Each stimulus causes a twitch. If stimuli are delivered slowly enough, the tension in the muscle will relax between successive twitches. If stimuli are delivered at high frequency, the twitches will overlap, resulting in tetanic contraction.
The stimulus–response model emphasizes the relation between stimulus and behavior rather than an animal's internal processes (i.e., in the nervous system). [2] In experimental psychology, a stimulus is the event or object to which a response is measured. Thus, not everything that is presented to participants qualifies as stimulus.
The stimulus modality for vision is light; the human eye is able to access only a limited section of the electromagnetic spectrum, between 380 and 760 nanometres. [3] Specific inhibitory responses that take place in the visual cortex help create a visual focus on a specific point rather than the entire surrounding.
Physiology (/ ˌ f ɪ z i ˈ ɒ l ə dʒ i /; from Ancient Greek φύσις (phúsis) 'nature, origin' and -λογία () 'study of') [1] is the scientific study of functions and mechanisms in a living system.