Respuesta :
Answer:
Our heart is divided into four chambers. The upper two chambers are called atria and the lower two chambers are called ventricles.
Explanation:
The right atrium receives deoxygenated blood through two large veins called venae cavae. The left atrium receives oxygenated blood from lungs through two pairs of pulmonary veins. Once both the upper chambers are filled, pressure develops and the valves between atria and ventricles open (AV valve). Opening of these valves allows blood to enter ventricles. Now ventricular contraction begins during which the AV valve close to prevent the back flow of blood into atria. When the pressure in ventricles increase it results in opening of semilunar valves allowing the blood from right ventricle (deoxygenated) to pass through pulmonary artery to lungs and blood from left ventricle (oxygenated) to pass through aorta to various body parts.
