Why is gaseous exchange in the circulatory system important to man's survival

The circulatory and respiratory systems absorb oxygen from the air and transfer it to all parts of the body while absorbing carbon dioxide from the body and releasing it into the air.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

answer; both surfaces of the membrane are nonpermeable