Humans blink once every five or six seconds, and each blink lasts about one-sixth of a second. If you add it up, you blink more than three million times per year. The main purpose of blinking is to moisten and clean the cornea and the conjunctiva, two membranes of the eye. In fact, your eyes would dry out if they stayed open all the time. But the eye also blinks if an object or person approaches quickly.
- What are the five main senses?
- Why do people get wrinkles and gray hair as they get older?
- Why do zits always form in the middle of the forehead?
- What causes goose bumps?
- Why do I have a belly button?
- Why is the skin between my toes sometimes red and itchy?
- Will a wart go away if I wrap it in duct tape?
- What is a seed drill?
- My grandmother has a lump on her chin that sprouts hair. What is this?
- Why doesn’t it hurt to cut my hair?
- Why do my fingers get all pruney in the bathtub?
- How does the body cool off?
- Why do some people have freckles?
- Why do people have different color skin?
- Which hair grows the fastest?
- How many hairs do I have on my head?
- What is pus?
- Why do scabs form?
- Who invented the earliest milking machines?
- What causes a bruise?
