All synthetic materials ultimately come from

Factories-i.e. created from humans

Explanation:

Synthetic materials, like polyester, nylon and acrylic, don't exist naturally but are made in factories. Synthetics are created through an industrial manufacturing process in which petroleum, a fossil fuel, is extracted from the earth and mechanically transformed into fibers for clothing.

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.

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explanation: