- from Muscles
You inhale about 25,000 times a day, and you swallow dozens of times in a single meal.
Your heart beats between 60 and 100 times a minute, even when you aren’t doing much. Suppose you had to actually tell each and every muscle how and when to contract and relax. You wouldn’t have time to do anything else! But you don’t have to do that, thanks to involuntary muscles, which work without you thinking about them at all. They function while you live your life.
There are two types of involuntary muscles: smooth muscles and cardiac muscles.