1. The reaction of a muscle, nerve, gland, or other excitable tissue to a stimulus. 2. Any act or behavior, or its constituents, that a living organism is capable of emitting. Reflexes are usually excluded because they are typically elicited by a specifiable (unconditioned or natural) stimulus rather than emitted under circumstances in which the stimulus was not specifiable. [L. responsus, an answer]
- auditory brainstem r. (ABR) an electrophysiologic measure of auditory function utilizing computer-averaged responses produced by the auditory nerve and the central auditory pathways principally in the brainstem to repetitive acoustic stimuli. ABR is also used to locate the lesion and determine the type of hearing impairment (sensory versus neural). SYN: brainstem evoked r..
- automatic auditory brainstem r. a technique of ABR in which the stimulus modification is programmed on the basis of the electrical responses recorded. The device determines automatically if predetermined thresholds have been achieved. It is useful in newborn hearing screening.
- biphasic r. 1. two separate and distinct responses that are separated in time; 2. immediate reaction to an antigenic challenge followed by a recurrence of symptoms after an interval of quiescence.
- blink r. a r. elicited during nerve conduction studies, consisting of muscle action potentials evoked from orbicularis oculi muscles after brief electric or mechanical stimuli to the cutaneous area supplied by the ophthalmic branch of the trigeminal nerve. Characteristically, there is an early r. (approximately 10 ms after stimulus) ipsilateral to the stimulation site (labeled R1) and bilateral late responses (approximately 30 ms after stimulus; labeled R2); the latter are responsible for the visible twitch of the orbicularis oculi muscles.
- conditioned r. a r. already in an individual's repertoire but which, through repeated pairings with its natural stimulus, has been acquired or conditioned anew to a previously neutral or conditioned stimulus. See conditioning. Cf.:unconditioned r..
- depletion r. subnormal metabolic r. to trauma in a person whose physiologic processes are already depressed by disease.
- evoked r. an alteration in the electrical activity of a region of the nervous system through which an incoming sensory stimulus is passing; may be somatosensory (SER), brainstem auditory (BAER), or visual (VER). SEE ALSO: evoked potential.
- flight or fight r. emergency theory.
- galvanic skin r. (GSR) a measure of changes in emotional arousal recorded by attaching electrodes to any part of the skin and recording changes in moment-to-moment perspiration and related autonomic nervous system activity. SYN: galvanic skin reaction, galvanic skin reflex, psychogalvanic reaction, psychogalvanic skin reaction, psychogalvanic reflex, psychogalvanic skin reflex, psychogalvanic r., psychogalvanic skin r..
- Henry-Gauer r. inhibition of antidiuretic hormone secretion due to a rise in atrial pressure that stimulates atrial stretch receptors.
- immune r. 1. any r. of the immune system to an antigen including antibody production and/or cell-mediated immunity; 2. the r. of the immune system to an antigen (immunogen) that leads to the condition of induced sensitivity; the immune r. to the initial antigenic exposure (primary immune r.) is detectable, as a rule, only after a lag period of from several days to 2 weeks; the immune r. to a subsequent stimulus (secondary immune r.) by the same antigen is more rapid than in the case of the primary immune r..
- isomorphic r. a r. to trauma at sites of injury in previously uninvolved areas of patients with skin diseases such as psoriasis and lichen planus, typically with linear lesions at sites of scratching or a scar. SYN: Köbner phenomenon.
- late-phase r. recurrence of symptoms after an appreciable interval following challenge with an antigen; preceded by an initial early-phase r..
- level-dependent frequency r. one of several strategies used in hearing aid s to alter the balance in amplification between high- and low-frequency sounds.
- myotonic r. failure of muscle relaxation caused by repetitive discharge of muscle fiber action potentials.
- orienting r. SYN: orienting reflex.
- recruiting r. SYN: recruitment (2).
- relaxation r. an integrated hypothalamic reaction resulting in decreased sympathetic nervous system activity which, physiologically and psychologically, is almost a mirror image of the body's responses to Cannon emergency theory (flight or fight r.); can be self-induced through the use of techniques associated with transcendental meditation, yoga, and biofeedback. SEE ALSO: emergency theory.
- stringent r. the cellular r. to amino acid starvation that reduces the amount of ribosomes to what can be employed under the nutrient conditions.
- triple r. the triphasic r. to the firm stroking of the skin. Phase 1 is the sharply demarcated erythema that follows a momentary blanching of the skin and is the result of release of histamine from the mast cells. Phase 2 is the intense red flare extending beyond the margins of the line of pressure but in the same configuration, and is the result of arteriolar dilation; also called axon flare because it is mediated by axon reflex. Phase 3 is the appearance of a line wheal in the configuration of the original stroking.
- unconditioned r. a r., such as salivation, which is a part of the animal or human repertoire. Cf.:conditioned r..
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re·sponse ri-'spän(t)s n the activity or inhibition of previous activity of an organism or any of its parts resulting from stimulation <a conditioned \response>
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n.
the way in which the body or part of the body reacts to a stimulus. For example, a nerve impulse may produce the response of a contraction in a muscle that the nerve supplies.
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re·sponse (re-sponsґ) [L. respondere to answer, reply] an action or movement due to the application of a stimulus. Called also reaction.Medical dictionary. 2011.