By Heather Brown

MINNEAPOLIS (WCCO) — It’s Friday, and Heather Brown went to the mailbag to answer some of your burning Good Questions about the human body.

Gina from Lino Lakes asked: “Why do we twitch?”

St. Kate’s physiology professor Dr. Mark Blegen helped out with this answer. He says muscle twitching is caused by little muscle contractions. Those contractions happen when electrical impulses are conducted down a nerve. The twitching happens when there’s some kind of a disruption in the nerve.

He says it can happen spontaneously and there’s really no point to it. Eye twitching works the same way because it’s the muscle in your eyelid that twitches.

Haley from Minneapolis asked: “What is the purpose of tears?”

Scientists will tell you the tears that protect our eyes — by keeping them moist or keeping out dirt — are different from emotional tears. As for why we cry when we’re sad, the experts don’t all agree. But, the main theories are that tears are a signal, whether for empathy, protection or to get what we want.

Tears also have some chemicals in them the body makes when it’s stressed and crying is a way to get rid of them.

Tristan, 10, from Independence asked: “Why do your fingers and toes become wrinkled after we’ve been swimming for long time?”

According to Dr. Lisa Carney Anderson, a physiology professor at the University of Minnesota, our skin is good at being waterproof, but when we stay in water for a long time, the oils that protect us wear off. So, she says the water can creep into the skin and the blood vessels in our fingers and toes squeeze up to make those spots wrinkly.

Some scientists also believe there’s an evolutionary reason. They argue wrinkles give us a better grip in slippery conditions, so we can pick stuff up better or won’t fall or trip when we’re wet.


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