lungs & gas exchange

• oxygen is needed around the body as cellular respiration needs to take place
• 1. mouth/nose
  2. trachea
  3. bronchi
  4. bronchioles
  5. alveoli
• gas exchange happens in the alveoli
• how the alveoli is adapted for its function

  • made up of one layer of very thin cells making a short diffusion pathway
  • has a large surface area
  • walls are moist allowing gases to dissolve which increases the rate of diffusion
• deoxygenated blood from the body passes by and is then oxygenated by the lungs
• CO2 is exchanged as it diffuses from the blood in the capillaries into the air in the alveoli
• breathing rate= no. of breaths/no. of minutes
• bronchi- large branches
• bronchioles- small branches
• oxygen binds to the haemoglobin in the red blood cells
• Smoking causes lung disease, heart disease and certain cancers.
• Nicotine is the addictive substance in tobacco.
• Pathogens are microorganisms that cause disease.
• Sticky mucus in the lungs traps pathogens rather than being swept out of the lungs by the cilia on the epithelial cells lining the trachea, bronchi and bronchioles.
• Cigarette smoke contains harmful chemicals that paralyse the cilia, this leads to smokers cough as it guilds up mucus and less air can come in/out of the lungs.
• Smoke irritates the bronchi leading to bronchitis.
• Smoke damages the walls of the alveoli by breaking down the walls they join together leading to larger air spaces. This reduces the amount of oxygen in the blood. This can put strain on the heart and increases risk of coronary heart disease and strokes.
• Carbon monoxide combines with the haemoglobin in the red blood cells which reduces the ability for the blood to carry oxygen, putting a strain on the heart.
• Tobacco smoke contains carcinogens, including tar.
• Smoking increases the risk of lung cancer and cancer of the mouth, throat and oesophagus.