Respiratory system

• Respiratory system


  The body's breathing system
• Functions of the respiratory system


  • Brings oxygen from the atmosphere into the lungs
  • Provides a method of gas exchange that allows oxygen to enter the blood and carbon dioxide to leave the blood
  • Removes carbon dioxide and some water vapour from the lungs into the atmosphere
  • Enables a person to speak through the movement of air from the lungs through the vocal cords
• Parts of the respiratory system

  • Air passages
  • Lungs
  • Diaphragm
• Nasal cavity


  The nostrils form the entrance, small hairs called cilia filter out dust, pollen and other impurities, and the cavity warms and moistens air
• Pharynx


  Allows the passage of air and food, food is swallowed into the oesophagus and air passes into the larynx
• Larynx


  Often called the "voice box", air passes through it into the trachea, the epiglottis prevents food from entering the larynx
• Trachea


  The windpipe through which air passes to the bronchi, it must remain open or the whole respiratory system fails, it consists of strong cartilage rings
• Bronchi


  The trachea branches into two bronchi, one for each lung, they divide into smaller and smaller branches called bronchioles which end in millions of microscopic air sacs called alveoli
• Alveolus


  The microscopic air sacs where the exchange of oxygen for carbon dioxide takes place, they are surrounded by capillaries
• Diaphragm


  A dome-shaped muscle found below the lungs that separates the chest from the abdominal cavity, its movement is responsible for the process of breathing
• Breathing


  1. Inspiration - breathing in

  2. Expiration - breathing out
• Breathing


  Automatically controlled by the brain, which monitors the level of carbon dioxide in the blood and signals the diaphragm to move
• Adult men breathe 12-18 times per minute, women breathe slightly faster, breathing is slower and shallower at rest than when active or excited
• Inspiration


  The chest cavity expands as the diaphragm contracts and moves downwards, the intercostal muscles move the ribs upwards and outwards, decreasing the air pressure in the chest cavity and forcing air into the lungs
• Expiration


  The chest cavity returns to its "at rest" size and shape as the diaphragm relaxes and returns to its dome shape, and the ribs return to their original position, increasing the pressure in the chest cavity and forcing the lungs to expel air
• Yawns are extended inspirations, hiccups are noisy inspirations caused by irregular spasms of the diaphragm muscle
• Coughing is forced expiration, the air is forced quickly through the vocal cords causing the noise, it can help clear the lungs and bronchi of congestion but the expelled droplets can spread infection
• During physical activity, active forced breathing takes place to increase the chest capacity and amount of air moved in and out of the lungs, the diaphragm and intercostal muscles work harder and other muscles from the upper body help to give greater chest expansion