Breathing system

• Benefits of breathing through the nose

  • Filtered by hairs and mucous
  • Moistened and warmed allowing it to diffuse into capillaries in lungs easier
• Pharynx (Throat)

  • Epiglottis: Flap of tissue that closes off the trachea when we swallow
  • Larynx: Vocal cords - produces sound by vibrations
• Trachea (windpipe)

  • Air passes through here into the bronchi
  • Rings of cartilage (protein) protect the trachea
  • Contains mucous for capturing harmful bacteria and dust
  • Tiny hairs called cilia allow for an upward movement of mucous up past the epiglottis and down the oesophagus
• Bronchi & Bronchioles


  • The trachea divides into the bronchi found in the lungs
  • The bronchi further divide into bronchiole (narrower)
  • If a person suffers from asthma then their bronchiole are restricted
  • Asthma inhalers work by dilating the bronchiole
• Alveoli

  • Function: Gas exchange by diffusion
  • Oxygen enters the capillaries in exchange for carbon dioxide
  • Large surface area
  • Thin walled (one cell thick)
  • Rich blood supply
  • Numerous
• Gas Exchange

  1. Diffusion

  2. Oxygen travels through the blood by haemoglobin in red blood cells

  3. Carbon dioxide travels through the blood by plasma
• Breathing rate control


  • Medulla oblongata part of brain is responsible for involuntary processes e.g. breathing
  • Carbon dioxide levels in the blood control breathing rate (homeostasis)
  • Increased carbon dioxide in blood increasing breathing rate
• Inhalation process

  1. Brain sends impulse to contract intercostal muscles and diaphragm

  2. Ribs move up and out. Diaphragm moves down

  3. Volume of the thoracic cavity (lungs) increases resulting in decreased pressure in the lungs

  4. The difference in pressure in the lungs and outside the body causes air to move in
• Asthma

  • Symptoms: Wheezy breathing and feeling of breathlessness
  • Cause: Dust or allergens
  • Prevention: Stay away from dusty areas and allergens
  • Treatment: Inhaler