Stimulus (physiology)

The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism—directional growth (2.) toward the light stimulus.

In physiology, a stimulus[1] is a detectable change in the physical or chemical structure of an organism's internal or external environment. The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity (excitability).[2] Sensory receptors can receive information from outside the body, as in touch receptors found in the skin or light receptors in the eye, as well as from inside the body, as in chemoreceptors and mechanoreceptors. When a stimulus is detected by a sensory receptor, it can elicit a reflex via stimulus transduction. An internal stimulus is often the first component of a homeostatic control system. External stimuli are capable of producing systemic responses throughout the body, as in the fight-or-flight response. In order for a stimulus to be detected with high probability, its level of strength must exceed the absolute threshold; if a signal does reach threshold, the information is transmitted to the central nervous system (CNS), where it is integrated and a decision on how to react is made. Although stimuli commonly cause the body to respond, it is the CNS that finally determines whether a signal causes a reaction or not.

  1. ^ Prescriptivist's Corner: Foreign Plurals Archived 17 May 2019 at the Wayback Machine: "Biologists use stimuli, but stimuluses is in general use."
  2. ^ "Excitability – Latest research and news | Nature". www.nature.com. Archived from the original on 5 November 2021. Retrieved 8 August 2021.

From Wikipedia, the free encyclopedia · View on Wikipedia

Developed by Nelliwinne