respiratory system

• Structure of the respiratory system : • larynx trachea

  • bronchi

  • bronchioles

  • alveoli

  • diaphragm

  • intercostal muscles

  • pleural membranes
• Parts of the respiratory system :

  • Larynx : connects the back of the nose and the trachea, forming an air passage to the lungs. It is covered by a flap called the epiglottis which prevents food from entering the trachea.

  • The larynx also contains the muscles and ligaments that form the vocal cords allowing us to speak.
• Parts of the respiratory system

  • Trachea
  • Bronchi
  • Bronchioles
• Trachea


  Also known as the windpipe, leads from the larynx and divides to form 2 bronchi
• Bronchi


  Supply the left and right lungs
• Bronchioles


  Form a network reaching into the lungs
• Trachea and bronchi


  • Protected by rings of cartilage to prevent them from collapsing
  • Rings of the trachea are C-shaped to allow food to pass down the oesophagus
• Walls of the tubes


  • Contain muscles which can cause the tubes to dilate or constrict, altering the amount of air entering or leaving the lungs
  • Can cause the symptoms of asthma
• Lining of the tubes


  • Contains globular cells that produce mucus
  • Contains ciliated cells - the cilia are like microscopic hairs and together they work like a conveyor belt to remove particles back up the throat to be swallowed
  • Cilia are paralysed by chemicals in cigarette smoke - smoker's cough
• Alveoli are found at the ends of the smallest bronchioles. They are sacs found in clusters. A single sac is called an alveolus. Each is surrounded buy a capillary network where oxygen and carbon dioxide are exchanged across the alveolar membrane. There are about 300 million alveoli in the lungs.
• Diaphragm :

  This is a muscle attached to the lower ribs that separated the chest cavity from the abdomen.
• the intercostal muscles are located between and attached to the ribs. there are 2 sets : internal and external
• Pleural membranes cover the outside of the lungs and line the inside of the chest wall. Between the membranes is a narrow space filled with pleural fluid. This causes the membranes to stick together and move to prevent friction. One is attached directly to the lung and the other is attached to the ribcage and diaphragm.