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THE EVOLUTION OF THE HEART
• Heartis a muscular organ .
As per evolutionary point of view the chamber of heart are,
1.SINGLE CHAMBER HEART
• It is found in primitive chordates like amphioxus.
• It is not a true heart.

2. TWO CHAMBER HEART
• It is found in pises.
• It is true heart chamber.
• 2heart chamber
                 a. Atrium- receving chmber
                 b. Ventricle-pumping chamber






• 2 chanber animals also contains gills for respiration.
• Heart of fish receive only deoxygenated blood.
• This type heart is calledbranchialheart or venus heart.
• It is a single circulation path or haert.

Sinus                                 atrium                    ventricle
venosus                                                               
                                     
                                                                        conus arteriosus 
deoxyganated
blood
                           oxygenated                                                 
      organ                                         gills              aorta
                                blood
3. THREE CHAMBER HEART
• 3 Chamber heart is found in amphibius and reptile.
• 3chamberheart,
              a. Auricles- divided 2 chamber
                   i. Right auricle
                   ii. Left auricle
              b. Ventricle

• Respiration for lungs.
• It is a dubble circulation path.
• This type of heart pumps mixed blood is known as atreovenius heart.

4. FOUR CHAMBER HAERT
4 Chamber heart found in birds and mammals.         
                             Human heart
• The ventricle divided 2 chamber , left and right ventricle.
• In birds ventricle is not purely divided.
• It is dubble circulation path.

                           

                                                                       

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