Respiratory system

• What is the trachea?

  The trachea is the tube that connects the larynx to the bronchi, allowing air to pass in and out of the lungs.
• What are the lungs?

  Organs responsible for respiration. The lungs are found in the upper part of the chest called the thorax
• What is the bronchi?

  Airway in the respiratory system.
• What are the bronchioles?

  Small airways in the lungs.
• What are the alveoli?

  Tiny air sacs in the lungs where gas exchange occurs.
• What are the pleural membranes?

  The pleural membrane is a thin, slippery sack that covers the lungs and the inside of the chest cavity. It separates the two lungs and provides a barrier to keep them air tight
• What are the ribs?

  • They surround the chest cavity and protect vital organs such as the heart and lungs.
• What are the intercostal muscles?

  Muscles between the ribs.
• What is the diaphragm?

  The diaphragm is a dome-shaped muscle located below the lungs that helps with breathing.
• Alveoli

  • The wall is a single layer of epithelial cells
  • The wall of a capillary is a single layer of endothelial cells
  • Short diffusion distance for oxygen from the air in the alveoli to the red blood cells in the capillary
  • Easier for oxygen to get into the red blood cells
• Alveoli

  • Many alveoli mean there is a large surface for gas exchange
  • About 75m (squared) in an adult
• Ventilation of the lungs

  Maintains a high concentration of oxygen and low concentration of carbon dioxide in the air in the alveoli
• Blood supply

  1. Ensures that carbon dioxide is continually brought to the lungs and oxygen is carried away

  2. Helps maintain the high concentration gradient
• How gas exchange happens

  1. Oxygen and carbon dioxide are constantly being supplied and removed via breathing

  2. Oxygen can diffuse across the membrane of the cells that line the alveoli, to the outside of the cell

  3. The same applies for the lining of the capillaries, until oxygen eventually diffuses into the red blood cells, where it can bind with haemoglobin to make oxyhemoglobin

  4. Carbon dioxide can also diffuse across these membranes and enter the alveoli sacks to then exit the body via the alveolar duct

  5. While oxygen is being supplied, it's also being taken away due to blood flow

  6. This means we're constantly maintaining a concentration gradient which allows gas exchange to continue
• Explain the structure of the respiratory system.

  • The two lungs fill the thorax.

  • The mouth and nose lead to the trachea.

  • The trachea splits into two bronchi, one leading to each lung.

  • Bronchi divide into many bronchioles.

  • Bronchioles lead to alveoli.
• What 2 muscles does the process of inspiration involve?

  • The diaphragm contracts causing it to move down.

  • The external intercostal muscles contract causing the rib cage to move up and outwards.
• How does elastic tissue assist in expiration?

  It recoils, increasing the pressure in the lungs, helping to force air out.
• What muscles are involved in forced expiration?

  The internal intercostal muscles contract causing the rib cage to be pulled in and down more forcefully, expelling air more rapidly from the lungs.
• What 2 muscles are involved in expiration?


  • The rib cage relaxes causing it to move in and down.

  • The diaphragm relaxes causing it to move up.
• What are two other factors that help maximise the rate of diffusion?

  • Alveoli walls are coated in a film of moisture. Oxygen dissolves in the water before diffusing across the epithelium of the alveoli. Pulmonary surfactant, produced by some cells in the wall of the alveoli, coats the epithelial cells and reduces the surface tension of water. This makes it easier for the lungs to inflate and stops the surfaces of the alveoli sticking together.

  • Rate of diffusion increases with temperature, so body temperature helps to ensure maximum rate of diffusion.
• What is COPD?

  Chronic obstructive pulmonary disease is the name given to a group of lung diseases that cause difficulty breathing.

  COPD is a long-term, progressive lung condition. COPD is incurable, cannot be reversed and affects life expectancy.

  Treatment can keep the condition under control though.
• What causes COPD?

  • Smoking is the main cause of COPD and is responsible for about 90% of cases. Passive smoking may also increase the risk.

  • Exposure to types of dust and chemicals can increase the risk: cadmium dust, grain and flour dust, silica dust, welding fumes, isocyanates and coal dust.

  • It is additionally caused by genetic factors.

  • Air pollution
• What are the symptoms of COPD?

  • Shortness of breath (in early stages) this may only happen when exercising, but will gradually get worse. May also wake up at night feeling breathless.

  • Persistant chesty cough that produces large amounts of phlegm.

  • Frequent chest infections.

  • Persistant wheezing.
• What are steroid tablets and how do they treat COPD?

  Steroid tablets can be used in a bad flare up to reduce airway inflammation. This is usually a 5-day course treatment, as long-term use of steroids can cause weight gain, mood swings and weakened bones. You may also be prescribed steroid tablets if you have a chest infection.
• What lifestyle changes can help treat COPD?

  Stopping smoking prevents the disease from progressing.
• What is pulmonary rehabilitation?

  This is a programme is designed to help people with lung problems, by increasing the amount of exercise they can do. This is done in groups. The programme includes physical exercise, education, dietary advice, and emotional support.

  This is usually one or more group sessions per week, for 6 weeks.

  This is delivered by professionals like physiotherapist, dieticians and nurse specialists.
• What is a bullectomy?

  A bullectomy is when a pocket of air is removed from one of the lungs, so they can work better making breathing easier.
• What is a lung volume reduction surgery?

  A lung volume reduction surgery is when you remove a damaged section of the lung so the healthier parts to work better making breathing easier.