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In general, cellular response to stimuli is defined as a change in state or activity of a cell in terms of movement, secretion, enzyme production, or gene expression. [9] Receptors on cell surfaces are sensing components that monitor stimuli and respond to changes in the environment by relaying the signal to a control center for further ...
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction.
Irritability is the excitatory ability that living organisms have to respond to changes in their environment. [1] The term is used for both the physiological reaction to stimuli and for the pathological , abnormal or excessive sensitivity to stimuli.
The perception begins when thermal stimuli from a homeostatic set-point excite temperature specific sensory nerves in the skin. Then with the help of sensing range, specific thermosensory fibers respond to warmth and to cold. Then specific cutaneous cold and warm receptors conduct units that exhibit a discharge at constant skin temperature. [15]
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.
External receptors that respond to stimuli from outside the body are called exteroreceptors. [4] Exteroreceptors include chemoreceptors such as olfactory receptors and taste receptors, photoreceptors (), thermoreceptors (temperature), nociceptors (), hair cells (hearing and balance), and a number of other different mechanoreceptors for touch and proprioception (stretch, distortion and stress).
Nociceptors respond to potentially damaging stimuli by sending signals to the spinal cord and brain. This process, called nociception, usually causes the perception of pain. [16] They are found in internal organs, as well as on the surface of the body. Nociceptors detect different kinds of damaging stimuli or actual damage.
Response to stimuli: a response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion; for example, the leaves of a plant turning toward the sun (phototropism), and chemotaxis.