Circulatory and Respiratory

• RESPIRATORY SYSTEM and CIRCULATORY SYSTEM

  work together to ensure that cells receive the oxygen and nutrients they need for cellular respiration and function, while efficiently removing waste products like carbon dioxide
• RESPIRATORY SYSTEM

  an organ system responsible for the respiration, the process of obtaining oxygen from the external environment and eliminating carbon dioxide.
• Chondrichthyes - Comparative Anatomy Vertebrate Circulatory System

  • Single-circuit heart with 4 chambers
  • (Sinus venosus, Atrium, Ventricle, Conus arteriosus)
  • Atrium: thin-walled muscular sac
  • Ventricle: thick, muscular walls
  • Conus arteriosus leads into the ventral aorta
  • Sinus venosus receives blood & fills by suction when ventricle contracts, enlarging pericardial cavity
• Osteichthyes - Comparative Anatomy Vertebrate Circulatory System

  • Heart structure similar to cartilaginous fishes
  • Presence of a bulbus arteriosus instead of a conus arteriosus
  • Most teleosts are "cold-blooded" likely due to this heart structure
• Lungfish - Comparative Anatomy Vertebrate Circulatory System

  • Modifications enable separation of oxygenated blood from lungs and deoxygenated blood from elsewhere.
  • Formation of a spiral valve
  • Spiral valve alternately blocks & unblocks entrances to left and right pulmonary arches, sending unoxygenated blood to the skin & lungs.
  • Shortening of ventral aorta helps ensure oxygenated & unoxygenated blood remains separate in the heart, moving directly into appropriate vessels
• Reptiles - Comparative Anatomy Vertebrate Circulatory System

  • Lizards have a muscular septum partially dividing the ventricle.
  • When the ventricle contracts, opening in septum closes, momentarily dividing ventricle into two separate chambers.
  • Left half of ventricle pumps oxygenated blood (from left atrium) to body.
  • Right half pumps deoxygenated blood (from right atrium) to lungs.
• Atria empty into


  Single ventricle
• Ventricle


  • Divided into narrow chambers to reduce mixing of blood
• Amniotes - Comparative Anatomy Vertebrate Circulatory System

  • Heart consists of 2 atria & 2 ventricles, with a sinus venosus except in adult birds & mammals.
  • Complete interatrial septum. and interventricular septum found only in crocodilians, birds, & mammals
• Aves + Mammals - Comparative Anatomy Vertebrate Circulatory System

  • 4 chambers in the heart
  • Complete septum with no mixing of blood
  • Pulmonary for gas exchange with the environment
  • Systemic for gas exchange (and all other exchange needs) of the rest of the body
• Complete interventricular septum + division of ventral aorta into 2 trunks


  1. Pulmonary trunk takes blood to the lungs

  2. Aortic trunk takes blood to the rest of the body
• Result of modifications: All blood returning to right side of heart goes to the lungs; blood returning from lungs to the left side of heart goes to systemic circulation
• Arterial Channel - supply most tissues with oxygenated blood (but carry deoxygenated blood to respiratory organs)
• Basic Pattern of Arterial Channel:

  • the ventral aorta emerges from the heart and passes beneath pharynx
  • the dorsal aorta emerges to the body and passes above digestive tract
  • 6 pairs of aortic arches connects the dorsal and ventral aortas
• Fishes - Aortic Arch

  • Ventral aorta extends forward below the pharynx & connects developing aortic arches. The first pair of arches develop first.
  • Segments of the first pair are lost & remaining sections become different pseudo branchial arteries.
  • Arches 2 - 6 become occluded
  • dorsal segments = efferent branchial arteries
  • ventral segments = afferent branchial arteries
  • Capillary beds develop within nine demi branches
• Tetrapods Aortic Arch

  • embryos have 6 pairs of aortic arches
  • but the 1st & 2nd arches are temporary & not found in adults
  • the 3rd aortic arches & the paired dorsal aortas anterior to arch 3 are called the internal carotid arteries
  • the 4th aortic arches are called the systemic arches
  • the 5th aortic arch is usually lost
  • the pulmonary arteries branch off the 6th arches & supply blood to the lungs
• FISHES

  Respiratory Organ - Gills

  Heart - 2 chambered

  Type of Circulation - Single circulation
• AMPHIBIANS

  • Respiratory Organ - Cutaneous Respiration and Lungs
  • Heart - 3 chambered
  • Type of Circulation - Double circulation (Pulmonary and Systemic)
• AMPHIBIANS

  • Respiratory Organ - Cutaneous Respiration and Lungs
  • Heart - 3 chambered
  • Type of Circulation - Double circulation (Pulmonary and Systemic)
• REPTILES

  • Respiratory Organ - Lungs and Other Accessory Breathing Organs
  • Heart - "5 chambered heart"
  • Type of Circulation - Double circulation (Pulmonary and Systemic)
• BIRDS

  • Respiratory Organ - Lungs and Air sacs (undirectional)
  • Heart - 4 chambered
  • Type of Circulation - Double circulation (Pulmonary and Systemic)
• MAMMALS

  • Respiratory Organ - Lungs (bidirectional)
  • Heart - 4 chambered
  • Type of Circulation - Double circulation (Pulmonary and Systemic)