COMPARATIVE ANATOMY: HEART OF RABBIT AND FROG

Rabbit

Frog

1. The heart of rabbit is four chambered with two auricles and two ventricles

1. The heart of frog is three chambered with two auricles and one ventricle.

2. Sinus venosus is absent as it is fused into right auricle

2. Sinus venosus is triangular chamber present on the dorsal side of heart and opens into right auricle.

3. Truncus arteriosus is absent and it is absorbed into the right ventricle

3. Truncus arteriosus is present on the ventral side of heart and it emerges from the right side of ventricle.

4. The right auricle receives blood from different organs of the body by two superior venae cavae (precavals)and one inferior vena cava (post - caval)

4. The blood from different organs of the body is collected by two precavals and one post caval which drain the blood into sinus venosus and then into right auricle.

5. Valves are absent at the opening of precavals into the right auricle. But the opening of posterior vena cava is guarded by Eustachian valve.

5. A pair of sinu-auricular valves guard the opening of sinus venosus into the right auricle.

6. The right auricle and left auricle open into right and left ventricles by auriculo-ventricular apertures which are guarded by tricuspid and bicuspid valves respectively

6. The auriculo - ventricular aperture is guarded by two pairs of auriculo- ventricular valves.

7. A large carotico-systemic trunk arises from the left ventricle and supplies blood to different organs.

7. A large truncus arteriosusoriginates from the right side of ventricle and divides into carotid, systemic and pulmocutaneous arches on either side.

8. A pulmonary aorta originates from right ventricle that supplies deoxygenated blood to the lungs.

8. The deoxygenated blood is carried to the lungs and skin by pulmo-cutaneous arch on either side of truncus arteriosus.

9. Three semilunar valves arepresent at the base of pulmonary aorta and also at the base of carotico systemic trunk.

9. Three semilunar valves arepresent at the base of truncus arteriosus.

10. Any valve is absent in the caro­tico systemic trunk

10. Truncus arteriosus consists of a longitudinal spiral valve to give mechanical strength to it.

11. Two pace makers namely S.A node and A.V. node are present in the wall of the heart.

11. Only a single pace maker namely S.A node is present on the wall of heart.

12. Bundle of His and purkinje fibres are present for transmi­ssion of impulses to the wall of myocardium of ventricles.

12. Bundle of His and purkinje Fibers are absent.