The Respiratory System

• Correct composition of inhale air: Oxygen 21%, carbon dioxide 0.04%, nitrogen 79%.
• Correct composition of exhaled air: Oxygen 16%, Carbon dioxide 4%, 79% Nitrogen, 1% other gases.
• The air travels through the trachea to reach the lungs
• The order of breathing in: Mouth/nose -> Trachea -> Bronchi -> Bronchioles -> Alveoli.
• The diaphragm is responsible for inspiration. It moves to a flat position when inhaling in order to push the lungs up, enabling air to rush in. When exhaling it moves to a dome shape, allowing the lungs to lower & air to rush out.
• Gaseous exchange takes place so that oxygen is passed into the blood so it can supply the whole body.
• When blood passes through the capillary next to the alveoli and gain high concentration of oxygen, this is called the concentration gradient.
• The oxygen in the alveoli diffuses into the capillary and is transported to the working muscles.
• The carbon dioxide from the capillaries diffuses into the alveoli in order to be exhaled by the lungs.
• Use terms like diffusion & high/low concentration in gaseous exchange questions
• Alveoli have a capillary not an artery
• The importance of the cardio-respiratory system.

  • The respiratory and cardio vascular system must work together in order to provide your body with oxygen and energy.
  • If you had an illness or deficiency in your respiratory system, it would be sure to weaken your cardio-vascular system.
• Vital capacity, tidal volume and VO2 max are measures that feature in sports training and evaluation. Sports coaches and physiotherapists use them to estimate the efficiency of a sportsperson's respiratory system.
• Vital capacity - The greatest amount of air that can be made to pass into and out of the lungs by the most forceful inspiration and expiration. Normally this is about four to five litres.
• Tidal volume - the amount of air inspired & expired with each normal breath at rest or during exercise.
• VO2 MAX - The volume of oxygen an athlete can consume per minute while exercising at maximum capacity.
• 3 sports where performers would have a very high VO2 max: swimming the channel, football, running a marathon
• In order to make a gaseous exchange as efficient as possible the alveoli have a very large surface area.
• Haemoglobin is an iron containing protein in red blood cells. It is responsible for carrying oxygen around the body.
• Alveoli work best when moist and clean. The body ensures moisture & cleanliness by creating mucus to make the air moist, in the nose.