Why does your heart never tire of constantly beating to pump blood throughout your body?

Our hearts beat every day for all our lives!!! It is made to not get tired. Its the stuff that you control that makes it work harder or normal.... If you want your heart to work normal though, stay away from clolestreol. THat makes your heart pump more things. ______________________________________________________________________ Cardiac muscle or NEVER get tired because cardiac muscle does not use produce lactic acid as a wate productHow_heart_works e-mail@hotmail.co.uk Elliottcollins