2. The mammalian support system is an
with an branches

osteocytes, nerves

Explanation:

The mammalian support system includes many of the osteocytes which are trapped within the bone matrix. The osteocytes maintain a connection through tiny channels also called canaliculi. Through these channels, the nerves pass through in the form of branches supplying water, and nutrients to the bone. This entire system is supportive of mammalian structure.

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.