Chain Reflex


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Chain Reflex

 

a complex reflex action consisting of a regular succession of comparatively simple reflex responses that together enable an organ or system of organs to perform their integral functions. The connections between the elementary reflex responses are conditioned by the functions of their reflex arcs. The reflex response of the effector of a given arc is a source of stimulation for the reflexogenic zone of another arc that is part of the chain reflex system. Consequently, chain reflexes are the result of a “chain” of simple reflex arcs based on the connection between the arcs’ receptor and effector endings. The central nervous system is informed of the completed reflex action by means of reverse signaling (feedback).

The term “chain reflex” was first used in 1899 by J. Loeb. Among those who elaborated the theory of chain reflexes were C. Sherrington, I. P. Pavlov, A. A. Ukhtomskii, and P. K. Anokhin. The concept of chain reflexes evolved from studies of the reflexes of the digestive, circulatory, respiratory, and excretory organs. Some examples of chain reflex action are swallowing, evacuation of the stomach’s contents into the duodenum, intestinal movement, and reflex respiratory activity. For all these organic functions, chain reflexes are the principal form of automatic self-regulation.

The chain reflex principle also plays a part in the innervation of the skeletal musculature. The muscles, tendons, and articular capsules contain a branched system of receptors that are stimulated by the reflex action of the effectors (such as muscle contraction, stretching of the tendons, or sliding of the joints’ surfaces) and are capable of eliciting new reflex actions both in their “own” and in other reflex arcs. However, the chain relations and the corresponding reflexes are of secondary significance for the somatic, or motor, reflex arcs; such relations and reflexes are subordinate in importance to the integrative action of the central nervous system that is the basis of complex motor activity in the organism, including both complex simultaneous and successive movement.

REFERENCES

See references under REFLEX and CONDITIONED REFLEX.

P. A. KISELEV