cardio-respiratory

• Pathway of air into the lungs

  1. Nose and mouth

  2. Trachea

  3. Bronchi

  4. Bronchioles

  5. Alveoli
• Trachea


  • Surrounded by rings of cartilage to keep its shape and prevent it collapsing
• Bronchi


  • The passage of air gets smaller and smaller
• Bronchioles


  • Branch out throughout the lungs and carry the air from the bronchi to the alveoli
• Alveoli


  • Tiny air sacs where the exchange of oxygen and carbon dioxide occurs
• Features that assist in gas exchange

  • Alveoli have very tiny air sacs with moist thin walls (only one cell thick)
  • Alveoli have a very large surface area
  • Alveoli are surrounded by capillaries
  • It provides a large blood supply
• Gases move from areas of high concentration to areas of low concentration


  Oxygen will move into the capillaries
• Gaseous exchange

  1. Oxygen is diffused into the blood

  2. Oxygen binds with the haemoglobin in the blood to form oxyhaemoglobin

  3. Oxyhaemoglobin is transported to the working muscles

  4. Carbon dioxide is produced and removed from the muscles by haemoglobin
• Vasoconstriction


  Blood vessels constrict to make them smaller. Chemical changes signal the nervous system to constrict blood vessels to inactive areas.
• Vasodilation


  Blood vessels dilate to make them bigger. Chemical changes signal the nervous system to dilate blood vessels that supply active areas.
• Artery


  • Thick muscular walls
  • Thick elastic walls
  • Small lumen (internal diameter)
  • Carry blood at high pressure
  • Carry blood away from the heart
  • Usually carry oxygenated blood (except the pulmonary artery)
• Vein


  • Thin walls
  • Large lumen (internal diameter)
  • Carry blood at low pressure
  • Contain valves
  • Mainly carry deoxygenated blood (except the pulmonary vein)
• Capillary


  • Very thin walls (one cell thick)
  • Small lumen (internal diameter)
  • Link smaller arteries with small veins
  • Allow gaseous exchange
  • Carry blood at low pressure
• When we exercise

  Blood is diverted away from inactive areas to the working muscles
• Cardiac cycle 1

  1. Right atrium contracts (systole) ejecting deoxygenated blood through a valve into the right ventricle

  2. Right ventricle is relaxed (diastole) and fills with deoxygenated blood

  3. Right ventricle contracts (systole) pushing deoxygenated blood through valves to the pulmonary artery

  4. Pulmonary artery carries deoxygenated blood away from the heart to the lungs where it becomes oxygenated
• Expiration

  • Diaphragm and external intercostal muscles relax
  • internal intercostals contract, lowering the ribs downwards and inwards
  • decreasing the volume of the chest cavity and causing the air to be forced out of the lungs
• Inhaling and exhaling during exercise

  1. During inspiration: Pectorals and sternocleidomastoid muscles raise the sternum allowing the lungs to expand further

  2. During expiration: Rib cage is pulled down quicker due to the contraction of the abdominal muscles
• Cardiac Output


  Amount of blood leaving the heart per minute
• Stroke Volume


  Amount of blood ejected from the heart per beat
• Heart Rate


  Number of times the heart beats per minute
• Cardiac Output

  Stroke Volume x Heart Rate
• Tidal volume during exercise increases. Breathing rate and depth increase to meet the demand of oxygen, and carbon dioxide is also removed
• Tidal Volume


  Amount of air inspired or expired in a normal breath
• Vital Capacity


  Maximum amount of air the lungs can expire after maximum inspiration
• Expiratory Reserve Volume


  Maximum volume of air that can be exhaled in addition to tidal volume
• Inspiratory Reserve Volume


  Maximum volume of air that can be inhaled in addition to tidal volume
• Residual Volume


  Amount of air that remains in the lungs even after a forced maximal exhalation
• Inspiration


  • Diaphragm and external intercostal muscles contract
  • external intercostal muscles raise the ribs upwards and outwards
  • increasing the volume of the chest cavity and causing air to rush into the lungs
• Cardiac cycle 2


  5. Vena cava brings the deoxygenated blood back to the heart and into the right atrium

  6. Pulmonary vein transports the oxygenated blood back to the heart and into the left atrium, which fills with oxygenated blood

  7. Left ventricle contracts (systole) pushing the oxygenated blood through valves to the aorta

  8. Left ventricle is relaxed (diastole) and fills with oxygenated blood

  9. Left atrium contracts (systole) ejecting oxygenated blood through a valve and into the left ventricle