Respiratory System and Ventilation

• Label the parts of the lungs.

  1] Larynx 2] Trachea 3] Bronchi 4] Alveoli 5] Bronchioles 6] Lung 7] Ribs 8] Diaphragm 9] Intercostal muscles 10] Thorax 11] Abdomen

  
• Why is inhaled air usually at a lower temperature than exhaled air?

  Air is warmed in the lungs because body temperature is 37 degrees celsius.
• In a road accident, a broken rib punctured a hole through the chest wall of a person, it was possible to hear air being sucked in and out of the wound. Explain why it is important to block the hole as soon as possible.

  The thorax must be airtight so when the diaphragm and intercostal muscles contract it causes the pressure to decrease in the chest cavity and air to flow into the lungs (otherwise air flows into the chest cavity not the lungs).
• Find out and describe briefly how to carry mouth to mouth ventilation (the ‘kiss of life’) which is given to someone whose breathing may be stopped.

  Ventilation is achieved through manual inflation of the lungs either by the rescuer blowing into the patient's lungs, or by using a mechanical device to do so.
• Breathing in

  • The intercostal muscles contract and the rib cage lifts. 
  • The diaphragm contracts and moves downwards. 
  • The volume inside the chest increases. 
  • The pressure inside the chest decreases and air flows into the lungs through the mouth.
• Breathing out

  • The intercostal muscles relax and the rib cage returns to its resting position. 
  • The diaphragm relaxes and moves upwards. 
  • The volume inside the chest decreases. 
  • The pressure inside the chest increases and air flows out of the lungs through the mouth.
• The Thorax and the Lungs

  • The diaphragm separates the thorax from the abdomen.
  • Alveoli has a good blood supply.
  • Ribs protect the lungs.
  • Trachea is supported by rings of cartilage.
  • Trachea divides to form two bronchi.
• Ventilation


  The process that moves air in and out of the lungs.
• Trachea


  The windpipe connects the mouth/nose to the lungs.
• Bronchioles


  The smallest air passages found in the lungs.
• Bronchus


  An air passage linking the trachea to the bronchioles.
• Diaphragm


  Dome shaped muscle at the base of the lungs.
• Intercostal Muscles


  Muscles between the ribs which contract to pull the ribs up when we breathe in.
• What are the similarities between the bell jar model and the thorax? 

  • Lungs (balloons), rib cage (bell jar), trachea (glass tube at the top), diaphragm (rubber sheet) are represented
  • The model is air tight
  • The lungs expands and relax
  • The whole of the rubber sheet diaphragm can contract in the model
• What are the differences between the bell jar model and the thorax?

  • In the human thorax, the lungs fill the space, whilst in the model, they do not fill the jar.
  •  In the human thorax, the ribcage moves: upwards and outwards (when breathing in) and downwards and inwards (when breathing out). The jar is unable to move in the model.
• What are the differences between the bell jar model and the thorax?

  • In the human diaphragm, blood vessels pass through the diaphragm, which does not happen in the model.