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 Life of "What Is Life" on his 2005 tribute CD "Something for George". "What Is Life" was performed live at George Fest 2014 by "Weird Al" Yankovic. The recording is available on YouTube. The following musicians are believed to have played on "What Is Life": What Is Life "What Is Life" is a song by the English musician George Harrison, released on his 1970 triple album "All Things Must Pass". In many countries, it was issued as the second single from the album, in February 1971, becoming a top-ten hit in the United States, Canada and elsewhere, and topping singles charts