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
I Wouldn't Normally Do This Kind of Thing I Wouldn't Normally Do This Kind of Thing "I Wouldn't Normally Do This Kind of Thing" is the third single from Pet Shop Boys' fifth album "Very". It was released in the UK by Parlophone Records on 29 November 1993, where it eventually reached number 13 in the chart. It reached number 2 on the US Club chart where it was released in January 1994. It appears to describe a person, normally hesitant to unwind and show his feelings, who—because of some event in his life (possibly a love interest)—suddenly becomes willing to let it all hang out. It is