A noxious stimulus is a
stimulus strong enough to threaten the body's integrity (i.e. cause damage to
tissue). Noxious stimulation induces peripheral
afferents responsible for
transducing pain (including
A-delta and
C- nerve fibers, as well as
free nerve endings) throughout the
nervous system
In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...
of an organism.
The ability to perceive noxious stimuli is a prerequisite for
nociception, which itself is a prerequisite for
nociceptive pain.
A noxious stimulus has been seen to drive
nocifensive behavioral responses, which are responses to noxious or painful stimuli. These include
reflexive,
escape behaviors, to avoid harm to an organism's body.
Because of rare genetic conditions that inhibit the ability to perceive physical pain, such a
congenital insensitivity to pain and anhydrosis (CIPA) noxious stimulation does not invariably lead to tissue damage.
Noxious stimuli can either be
mechanical (e.g.
pinching or other tissue
deformation),
chemical
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...
(e.g. exposure to
acid
An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...
or
irritant), or
thermal (e.g. high or low
temperature
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
s).
There are some types of tissue damage that are not detected by any
sensory receptors, and thus cannot cause pain. Therefore, not all noxious stimuli are adequate stimuli of
nociceptors. The adequate stimuli of nociceptors are termed ''nociceptive stimuli''.
References
{{Pain
Pain
Nociception
Sensory systems