How does skeletal and circulatory system work together

circulatory system delivers oxygen-rich blood to your bones.While , your bones are busy making new blood cells

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .