threshold

threshold /thresh·old/ (thresh´old) the level that must be reached for an effect to be produced, as the degree of intensity of a stimulus that just produces a sensation, or the concentration that must be present in the blood before certain substances are excreted by the kidney (renal t.) .

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thresh·old (thrshld, -hld)

n.

1. The place or point of beginning; the outset.

2. The lowest point at which a stimulus begins to produce a sensation.

3. The minimal stimulus that produces excitation of any structure, eliciting a motor response.

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threshold (thresh´ōld),

n the lowest limit of stimulus capable of producing an impression on the consciousness or evoking a response in irritable tissue.

threshold dose,

n See dose, threshhold.

threshold, high pain,

n higher than average capacity to withstand pain; exceptional pain tolerance.

threshold, low pain,

n lower than average capacity to withstand pain; minimal pain tolerance.

threshold, swallowing,

n the minimal stimulation required to initiate the reflex action of deglutition.

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threshold

the level that must be reached for an effect to be produced, as the degree of intensity of stimulus which just produces a sensation.

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threshold phenomenon

a theory explaining pruritus which states that some degree of pruritus is tolerated by a patient, but a small increase from an additional source raises the patient above their threshold and causes clinical signs.

renal threshold

that concentration of a substance in plasma at which it begins to be excreted in the urine.

threshold traits

heritable traits which have specific thresholds, e.g. four rather than three toes on a guinea pig's hindfeet, alive or dead at a specific age.

threshold unit

the distance between two thresholds when an inherited abnormality can occur at a number of levels, e.g. completely patent ductus arteriosus, through partial closure (ductus diverticulum) and complete closure. See also threshold traits (above).