Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Heather on 06/09/2008 15:42:59

Title: Why do some drugs cause the pupils to dilate?
Post by: Heather on 06/09/2008 15:42:59

Heather asked the Naked Scientists:

I recently discovered your podcast (http://www.thenakedscientists.com/HTML/podcasts/) and am trying to catch up and listen to all
of the previous downloads!

In a recent show you talked about why our eyes dilate in the dark.  Does
the explication that it has to do with a chemical process also apply to why
people who take hallucinogenic drugs have dilated pupils?

What do you think?

Title: Why do some drugs cause the pupils to dilate?
Post by: RD on 06/09/2008 16:00:54

"Street" drugs can cause large dilated pupils and tiny constricted "pinpoint" pupils...

Quote

Signs of [opiate] intoxication are decreased respiratory rate and pinpoint pupils.

http://www.emedicine.com/EMERG/topic20.htm

Title: Why do some drugs cause the pupils to dilate?
Post by: Bored chemist on 06/09/2008 18:28:02

The drugs mimic or block the chemicals that the body uses as messengers to tell the eye's muscles to contract or relax.
There's more about those messengers here
http://en.wikipedia.org/wiki/Neurotransmitters