A. Heart,
B. Atria
C. receiving
D. daoxygahated,
E. backward
F. Four
G. two
H. oxygenatad,
I.pumping
J. valve
K. forward
L. blood vassel

Your 11. ______ is as big as your fist It has 12. ______ chambers with specific tasks to do. These chambers are to 13. _______ at the upper part (left and right atrium); 14. _______ ventricles at the lower part (left and right ventricle). The atria are the 15. ______ chambers of the heart. Left atrium receives 16. ______ blood from the lungs and the right atrium receives 17. _________ blood from the body. The ventricles are the 18. ______ chambers. Left ventricle pumps the blood into the body and the right ventricle pumps the blood into the lungs. Another important part of the heart is the 19. _______, it is between each atrium and ventricle that prevents the blood from flowing 20. _______. They are like a one-way door that keeps the blood moving in one direction. In addition, aorta is the main artery connected to other major arteries that delivers oxygenated blood. When the upper part of the heart contracts the lower part relaxes and when the lower part contracts the upper part relaxes.​​