In other words, contraction of radial smooth muscle causes dilation of the pupil. This explains the autonomic actions: 1  Increased release of acetylcholine by the parasympathetic nervous system causes contraction of circular smooth muscle. 2  This makes the pupil (the dark hole) smaller.he pupil is contricted or dilated by the contraction of smooth muscle in the iris. There are two types. One type is arranged in the circle near the pupil. When a circle of muscle contracts, the circle becomes smaller. Thus contraction of the circular muscle causes constriction of the pupil.
forÂ·evÂ·er. adv. 1. For everlasting time; eternally: No one can live forever.2. At all times; incessantly: was forever complaining about the job.. forever-for a very long or seemingly endless time; she took forever to write the paper; we had to wait forever and a day. forever and a day. colloquialism-a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech.
Infinite describes things that are endless, like the universe, or your Uncle Phil's jokes. Finite means something with an end, and when you add the prefix, in- meaning not, you get infinite: something that never, ever ends. If someone has read every single book about pyramids, you might say he as an infinite knowledge of ancient Egyptian culture, even though that's an exaggeration. He will sure stop talking about them at some point.