Circulatory System

• The heart is myogenic, it triggers its' own beat
• The chambers of the heart:

  • Right Atrium
  • Left Atrium
  • Right ventricle
  • Left ventricle

  
• The heart has AV valves.

  • The left AV valve is known as the bicuspid valve
  • The right AV valve is known as the tricuspid valve

  A) Bicuspid valve

  B) Tricuspid valve

  
• In humans and mammals blood flows in a double circuit.

  Oxygenated and deoxygenated blood are separate

  
• Blood leaves via pulmonary artery or Aorta
• The sino-atrial node (SAN) is located in the wall of the right atrium.

  Function: The pacemaker for the heart.

  
• The AVN is connected to conducting fibres called Purkyne fibres. Purkyne fibres are bundled together - 'Bundle of His'. The AVN detects the electrical excitation passing over the atria and transmits the electrical excitation down the Purkyne fibres. After a slight delay, which allows for the atria to contract first, this causes the ventricles to contract.

  
  

  Link:https://youtu.be/mKuBj2j_Hl0?feature=shared

  
• Transport System helps to bring substances from one exchange site to another quickly
• Types of circulatory system

  • Single circulatory system
  • Double circulatory system
• Multicellular organisms require transport systems to reduce diffusion distance and help supply all the requirements needed by the body.
• Open Circulatory System

  • No tissue fluid
  • Blood is NOT enclosed in blood vessels, flows freely through cavities
• Single Circulatory System


  • Blood passes through the heart once in a full circuit
  • Low pressure-limits delivery of oxygen/glucose - low activity levels

  
• Double Circulatory system

  • Blood passes through the heart twice in a single circuit of the whole body
  • Low pressure - blood doesn't travel very far, avoids bursting capillaries and surrounding alveoli
  • System circuit is high pressure due to travelling a greater distance