spasm

n. a sudden, involuntary muscle contraction. It may be continuous or sustained (tonic) or it may alternate between contraction and relaxation (clonic). A spasm may be restricted to a particular body part; for example, a vasospasm involves a blood vessel, and a bronchial spasm involves the bronchi. —spasmodic adj.

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Psychology term of the day

March 11th 2025

retinal densitometry

a method of measuring the absorptance characteristics of retinal photopigments. A light that is shone into the eye travels through the retina, is reflected back out of the eye by tissues behind the retina, and is measured. The light that emerges is compared to the original light to determine how much was absorbed.