Reflex action

In medicine, a reflex is an involuntary reaction of the body to a stimulus.

A 1913 edition of Webster's Dictionary defines reflex as meaning

"Of, pertaining to, or produced by, stimulus or excitation without the necessary intervention of consciousness."

and a reflex action as

"any action performed involuntarily in consequence of an impulse or impression transmitted along afferent nerves to a nerve center, from which it is reflected to an efferent nerve, and so calls into action certain muscles, organs, or cells."

Ivan Pavlov unintentionally launched the study of conditioning by establishing a way of producing what he called "conditional reflexes", i.e. reflexes that would only be seen conditional on previous experiences of the subject.

Reflex actions seen in humans include:

accommodation reflex
Achilles reflex
Babinski reflex
biceps stretch reflex
brachioradialis reflex
mammalian diving reflex
gag reflex
Gastroc-Soleus reflex
light reflex
patellar reflex
photic sneeze reflex
pupillary reflex
quadriceps reflex
salivation
triceps stretch reflex

Processes such as breathing. digestion and the maintenance of the heartbeat can also be regarded as reflex actions, according to some definitions of the term.

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