[C] Heart

• Label the basic vertebrate heart

  A) Ductus Cuvier

  B) Hepatic vein

  C) Sinus Venosus

  D) Sino-atrial valve

  E) Atrium

  F) Atrio-ventricular valve

  G) Ventricle

  H) Conus valves

  I) Bulbus cordis

  
• Conus arteriosus - with cardiac muscles

  Bulbus arteriosus - without cardiac muscles
• Gas exchange is fulfilled by blood passing through myocardium lumen
• Involuntary contraction is done by cardiac muscle

  • Started by the sinoatrial node or pacemaker in Sinus venosus
  • Mammals:
  • Atrioventricular node with Purkinje fibers
• Frank-Starling reflex

  • Venous return increases as muscles increase pressure on veins within
  • Returning venous blood to heart stretches heart chambers, leads to stronger contraction
• Sheet of tissue that encloses the heart

  Pericardium
• Lampreys

  • 3 chambered
  • Sinus venosus
  • Atrium
  • Ventricle
  • Prominent bulbus arteriosus
  • One-way valves
  • Sinoatrial valves
  • Atrioventricular valves
  • Semilunar valves

  
• Hagfishes

  • 3 chambered
  • Sinus venosus
  • Atrium
  • Ventricle
  • Branchial heart + Accessory hearts
• Lungfishes

  • 4 chambered
  • Sinus venosus
  • Atrium
  • ventricle
  • Bulbus or conus arteriosus
  • Incomplete internal septation
  • Ventricle divided only partially
  • One-way valve
  • Sinoatrial valve
  • Atrioventricular plug
  • Spiral valve

  
• Amphibians

  • 4 chambered
  • Sinus venosus, atrium, bulbus arteriosus
  • Ventricle without internal division
  • Incomplete internal septation
  • One-way valves
  • Sinoatrial valves
  • Atrioventricular plug
  • Spiral valve
  • Compensation of pulmonary respiration via cutaneous respiration during diving
• Chelonians/Squamates

  • Sinus venosus reduced, contains pacemaker
  • Atrium divided into left and right
  • Bulbus cordis divided into pulmonary trunk + left and right systemic trunks
  • Ventricle compartments:
  • Cavum venosum
  • Cavum pulmonare
  • Cavum arteriosum - connects to venosum via interventricular canal
  • Cardiac right-to-left shunt
  • Blood returns to left side directly, moves to systemic circuit

  
• Crocodilians

  • Sinus venosus reduced
  • Atrium divided into left and right
  • Bulbus cordis divided into pulmonary trunk + left& right systemic trunks
  • Ventricle divided into left and right
  • Foramen of Panizza connects left and right AA
• Birds and Mammals

  • 4 chambered
  • Sinus venosus reduced in birds
  • Patch of Purkinje fibers (sinoatrial node) in mammals
  • Conus arteriosus → pulmonary trunk, aortic trunk
  • Parallel pumps
  • Left: Pulmonary circuit → systemic tissues
  • Right: Deoxygenated blood → pulmonary circuit
  • No cardiac shunting