Vertebrates, and a few invertebrates, have a closed circulatory system. Closed circulatory systems have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities.
I dont know if this is a true or false question but im going to go with false because anything you do that is physical is consider a exercise because you are using your body the muscles in your body to do physical things so basically doing physical activities is consider an exercise
It depends on the person, but I know that the average cycle is about 28 days long, and it only occurs once a month, in normal situations.
Hope this helps! :)
Stay smart,
~Mistermistyeyed.
