smooth muscle

any muscle that is not striated and is under the control of the autonomic nervous system (i.e., it is not under voluntary control). Smooth muscles are able to remain in a contracted state for long periods of time or maintain a pattern of rhythmic contractions indefinitely without fatigue. Smooth muscle is found, for example, in the digestive organs, blood vessels, and the muscles of the eyes. Also called involuntary muscle. Compare cardiac muscle; skeletal muscle.

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Psychology term of the day

February 23rd 2025

testis

n. (pl. testes) the principal male reproductive organ, a pair of which is normally located in the scrotum. The testes produce sperm in the seminiferous tubules (see spermatogenesis) and male sex hormones (androgens) in interstitial cells. See testicle. See also cryptorchidism; hypermobile testes.