Red blood cells are produced in the body and travel through arteries and
veins to all of the major organs. The
circulatory system is able to maintain
a relatively constant amount of red
blood cells because red blood cells
are regularly produced by -
F the bones of the skeletal system.
G the lymph of the circulatory
system.
H the glands of the endocrine
system.
J the neurons of the nervous
system.