3 stages of heart action:
stage 1 - when heart is relaxed between beats, blood flows into it. deoxygenated blood from body enters right atrium through superior and inferior vena cava. AT THE SAME TIME newly oxygenated blood from lungs enters left atrium through the pulmonary veins
stage 2 - muscles in right atrium contract to pump blood through the tricuspid valve into right ventricle. AT THE SAME TIME muscles in the left atrium contract to pump blood throughbicuspid valve into the left ventricle
stage 3 - muscles in right ventricle contract to pump blood through semilunar valves into pulmonary artery to travel to the lungs. muscles in left ventricle contract to pump blood through the semilunar valves into aorta, to travel around body again.
Comments
No comments have yet been made