Frog Function of Heart

1. The chambers of the heart beat in a rhythmic way.
2. First of all sinus venosus contracts. Then, the two atria contract. After this ventricle and finally truncus arteriosus is contracted.
3. The deoxygenated blood from the whole body except lungs is carried to sinus venosus by two precavals and one post caval.
4. Sinus, venosus opens into the right atrium through an opening.
5. Oxygenated blood from the lungs is brought into the the left atrium by two pulmonary veins.
6. Both the atria open into the ventricle and push their blood collectively into the ventricle by a common aperture, which is guarded by a valve.
7. This valve maintains the unidirectional flow of blood in the heart and prevents the back flow of blood.
8. In the middle of ventricle some mixing of oxygenated and deoxygenated blood takes place. On the two sides the blood remains unmixed due to rapid flow of blood.
9. When ventricle contracts the blood goes to the truncus arteriosus through an aperture. This aperture controls the speed and direction of the blood by a spiral valve present at the start of truncus arteriosus.