reflex (redirected from rectosphincteric reflex)

reflex: see nervous system.

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reflex

In biology, an automatic and inborn response to a stimulus that involves a nerve impulse passing from a sensory nerve cell to a muscle or gland without reaching the level of consciousness. Simple reflexes include sucking, swallowing, blinking, scratching, and the knee jerk. Most reflexes consist of complex patterns of many unconsciously coordinated muscular actions that form the basis of much instinctive behavior in animals. Examples include walking, standing, the cat's righting reflex, and basic sexual acts.

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reflex

1. 

a. an immediate involuntary response, esp one that is innate, such as coughing or removal of the hand from a hot surface, evoked by a given stimulus

b. (as modifier): a reflex action

2. 

a. a mechanical response to a particular situation, involving no conscious decision

b. (as modifier): a reflex response

3. a reflection; an image produced by or as if by reflection

4. Maths (of an angle) between 180? and 360?

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Reflex

A simple, unlearned, yet specific behavioral response to a specific stimulus. Reflexes are exhibited by virtually all animals from protozoa to primates. Along with other, more complex stimulus-bound responses such as fixed action patterns, they constitute much of the behavioral repertoire of invertebrates. In higher animals, such as primates, where learned behavior dominates, reflexes nevertheless persist as an important component of total behavior.

The simplest known reflexes require only one neuron or, in the strictest sense, none. For example, ciliated protozoa, which are single cells and have no neurons, nevertheless exhibit apparently reflexive behaviors. However, most reflexes require activity in a large sequence of neurons. The neurons involved in most reflexes are connected by specific synapses to form functional units in the nervous system. Such a sequence begins with sensory neurons and ends with effector cells such as skeletal muscles, smooth muscles, and glands, which are controlled by motor neurons. The central neurons which are often interposed between the sensory and motor neurons are called interneurons. The sensory side of the reflex arc conveys specificity as to which reflex will be activated. The remainder of the reflex response is governed by the specific synaptic connections that lead to the effector neurons. A familiar reflex is the knee-jerk or stretch reflex. It involves the patellar (kneecap) tendon and a group of upper leg muscles. Other muscle groups show similar reflexes.