Respiratory system

• Respiration


  Taking in of oxygen and the removal of carbon dioxide
• Respiration


  1. Ventilation - getting air in and out of the lungs

  2. External respiration - gas exchange between the lungs and the blood

  3. Transport of gases

  4. Internal respiration - exchange of gases between the blood in the capillaries and the body cells

  5. Cellular respiration - the metabolic reaction and the process that takes place in the cell to obtain energy from the fuel sources such as glucose
• Structure of the respiratory system


  • Nostril
  • Mouth
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
  • Pleural membranes
  • Intercostal muscles
  • Diaphragm
  • Esophagus
  • Epiglottis
• Air is a mixture of gases and is drawn into the body through the nose
• Passage of air


  1. Nose

  2. Larynx

  3. Trachea

  4. Bronchi

  5. Bronchioles

  6. Alveoli
• Diffusion


  Movement of gas molecules from an area of high concentration or partial pressure to an area of low concentration or partial pressure
• Gaseous exchange


  Movement of oxygen from the air in the blood and the carbon dioxide from the blood into the air
• The alveoli are responsible for the exchange of gases between the lungs and the blood
• Structure of the alveoli


  • Very thin walls for short diffusion pathway
  • Extensive capillary network for excellent blood supply
  • Huge surface area with millions of alveoli
• Gaseous exchange in the alveoli


  Occurs via diffusion from high to low partial pressure
• Mechanism of breathing


  • Air moves from high pressure to low pressure via diffusion
  • Increasing volume of thoracic cavity reduces pressure in lungs
  • Decreasing volume of thoracic cavity increases pressure in lungs
• Ventilation - Inspiration


  1. Diaphragm contracts and external intercostal muscles contract

  2. Ribcage moves upwards and outwards
• Ventilation - Expiration


  1. Diaphragm and external intercostal muscles relax

  2. Ribcage falls

  3. Lungs reduce in volume
• Tidal volume


  Volume of air breathed in or out per breath
• Inspiration reserve volume


  Volume of air that can be forcibly inspired after a normal breath
• Expiration reserve volume


  Volume of air that can be forcibly expired after a normal breath
• Residual volume


  Amount of air that remains in the lungs after maximum expiration
• Residual volume remains in the lungs due to air in alveoli, bronchioles and trachea held open by cartilage
• Lung volumes/capacities


  • Tidal volume
  • Inspiration reserve volume
  • Expiration reserve volume
  • Residual volume
• Minute ventilation


  Volume of air inhaled or exhaled from the lungs per minute
• Minute ventilation increases during exercise to meet extra oxygen demand
• Spirometer


  Device used to measure the volume of air inspired and expired by the lungs
• Spirometer trace shows changes in tidal volume, inspiration reserve volume and expiration reserve volume during exercise