The right atria→ right ventricle→ pulmonary trunk→ left or right pulmonary artery→ capillary bed of the lungs→ pulmonary veins→ left atrium→ left ventricle→ aorta→ capillary beds of the body.
Explanation:
Blood poor n oxygen enters into the heart through the inferior and superior vena cava into the Right Atria, as the atrium contracts the blood flows into the Right Ventricle through the open tricuspid valve which shuts when full in order to prevent the blood from flowing back into the right atria. The ventricle contracts and blood enters into the Pulmonary trunk and into the Left of Right Pulmonary Arteries and then into the Capillary beds of the lungs where it is oxygenated (CO2 is exchanged for O2).
The oxygenated blood then flows from the capillary beds of the lungs into the Pulmonary veins and then into the Left atrium. The atrium contracts and blood flows into the Left ventricle through the open mitral valve which thereafter shuts to prevent backflow of blood into the atrium while the ventricle contracts. As the ventricle contracts, the blood enters into the Aorta and to the arteries and spread to Capillary beds of the body.
