Helium has an atomic number of two so for its outer energy level is full. Helium is considered

Helium is considered as noble gas or inert gas because it belongs to noble family in the periodic table.

Explanation:

Helium is stable atom because it has complete outermost shell i. e. 2 electrons. Except noble gases, all the elements are reactive because they have incomplete outermost shell so for attaining stability, they form bonds with each other and attain the electronic configuration of noble gases. Helium has given the name of noble gas due to stability.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.