Mydriasis iris sphincter, composed of circularly arranged muscle fibers, and the iris dilator, composed of radially arranged muscle fibers. The sphincter is innervated by (signaled by nerves of) the parasympathetic nervous system, and the dilator by the sympathetic nervous system. Sympathetic stimulation of the adrenergic receptors causes the contraction of the radial muscle and subsequent dilation of the pupil. Conversely, parasympathetic stimulation causes contraction of the circular muscle and constriction of the pupil. The mechanism of mydriasis depends on the agent being used. It usually involves either a disruption of the parasympathetic nerve supply to the eye (which normally constricts the
(What Is) Love? (What Is) Love? "(What Is) Love?" is a song recorded by American entertainer Jennifer Lopez. Originally entitled "What Is Love?", the song appeared on the soundtrack to "The Back-up Plan" (2010), a film in which Lopez stars. The song was later included on Lopez's seventh studio album "Love?" (2011), as the album's title track. "(What Is) Love?" is a midtempo electropop song written by Diana "Wynter" Gordon, with the song's producer Emile "D'Mile" Dernst II. The song is about "not knowing what love is," according to Gordon. A remix of "(What Is) Love?", entitled "What Is Love? Part II", was