Gas exchange and transport

• arteries: carry blood away from heart (have thick muscular walls)
• veins: carry blood to the heart from the body
• capillaries: connect arteries to veins
• Heart diagram

  A) Vena Cava

  B) Pulmonary Valve

  C) Right atrium

  D) Right ventricle

  E) inferior vena cava

  F) descending artery

  G) septum

  H) left ventricle

  I) Left atrium

  J) pulmonary vein

  K) pulmonary artery

  L) Aorta

  
• Systemic circuit: left side of heart, blood to and from heart and body
• Pulmonary circuit: right side of heart, blood to and from lungs and heart
• Lymphatic system

  • is an open system
  • circulates lymph fluid
  • maintains osmotic and fluid balance in tissues, and supports immune defences
• Capillaries structural adaptations:

  • thin (one red blood cell) and permeable walls maximising nutrition, water, and gas exchange
  • carry blood at low pressure so they don't need muscular walls
  • moist walls allow gases to dissolve, allowing fast gas exchange
• Partial pressure: the pressure that a gas contributes to the total pressure of a gas mixture
• Haemoglobin: a protein containing iron found in red blood cells, bind oxygen molecules in red blood cells, allowing the transport of oxygen throughout the body
• Alveoli, capillaries, and bronchioles diagram

  A) Alveoli

  B) Capilaries

  C) Bronchioles

  
• Alveoli increase the surface area of the lungs for increased rate of diffusion of gases
• For efficient gas exchange:

  • large surface area
  • thin barrier to be crossed (cell membrane)
  • efficient removal of substance after transfer (blood flow)
  • adequate supply of gas (no ventilation means lower gas exchange)
• Fish have lamellae which have large surface area
• Pathway of air:

  1. Pharynx (back of mouth/throat)
  2. Trachea
  3. Bronchi
  4. Bronchioles
  5. Alveoli
• Alveoli is the site of gas exchange
• Alveoli and capillary gas exchange process:

  • oxygen dissolves in alveoli's moist inner surface
  • diffuses through capillary membrane into blood
  • carbon dioxide diffuses across capillary membrane into alveolus
• capillary and muscle tissue gas exchange process:

  • oxygen diffuses through capillary membrane into muscle tissue
  • carbon dioxide diffuses through capillary membrane into blood