The human cardiovascular system is considered closed because

There are no holes for blood to enter or leave the system

just put in mind that others aren't perfect. we all have problems that we feel makes us low of the low. but know that you are special and unique, that is what makes you out of this world : ). you might think and feel that others judge you, but mostly other people are scared if people judge them. just be happy, spend time with family, smile because that is the greatest medicine. a happy life. hope this : ))

is this a real question