Final answer:
A red blood cell travels from the right atria through the tricuspid valve into the right ventricle, then through the pulmonary valve to the pulmonary artery, the lungs, pulmonary veins, left atrium, mitral valve, left ventricle, and finally the aorta to the body.
Step-by-step explanation:
Imagine you are a red blood cell sitting in the right atria of the heart. As you begin your journey, the heart's rhythmic contractions nudge you through the tricuspid valve into the right ventricle. As the ventricle contracts, you're propelled up and out through the pulmonary valve and into the pulmonary artery. Now you're on your way to the lungs, where the pulmonary artery branches and takes you to the pulmonary capillaries. Here, you undergo a crucial exchange: you give up your carbon dioxide load and eagerly grab onto fresh oxygen molecules. Rich with oxygen, you then venture into the pulmonary veins, which usher you into the left atrium. Another contraction moves you through the mitral valve and into the muscular left ventricle. Finally, with a powerful push, the left ventricle sends you through the aorta, out into the vast network of vessels in the systemic circuit to deliver your precious cargo of oxygen to the body's cells, completing the cycle.