• Question: how does crying work?

    Asked by jayjay to Jo, Mark, Tim on 24 Jun 2010 in Categories: .
    • Photo: Joanna Buckley

      Joanna Buckley answered on 24 Jun 2010:

      Apparently, on average, men cry once every month and women cry at least five times per month, jayjay 🙂

      Crying requires something to make us cry and that’s different from person to person. When that happens, the nervous system stimulates the cranial nerve in the brain which sends signals via neurotransmitters to the tear glands.

      What’s weird is that we produce 3 different kinds of tears. Basal tears keep our eyes lubricated so they don’t try out. Reflex tears are produced when our eyes get irritated, like when you get a bit of grit in your eye. Man, that’s annoying! The third kind is the emotional type and the most amazing thing is that each type of tear contains different amounts of hormones and chemicals.


    • Photo: Tim Craggs

      Tim Craggs answered on 24 Jun 2010:

      Hi Jayjay,

      In each eye there is a tear gland, located over the outer corner of the eye. There are also ducts which carry the tears to the upper eyelid and canals which carry off the tears from the front of the eye. Every time we blink our eyelids, suction is exerted on the opening of the tear ducts which takes out some fluid. The purpose of this is to irrigate the cornea of the eye and prevent it from drying out. But, mechanically speaking, this is no different from crying.

      When we cry we get more of the liquid from these tear glands. It can be triggered by lots of different things, like the chemicals released when you chop an onion (http://www.loc.gov/rr/scitech/mysteries/onion.html) or emotions (both happy and sad).