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Respiratory System
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Respiratory System
• The respiratory system is mainly concerned with
breathing
• The function of the respiratory system is to get
oxygen into the body and carbon dioxide out of
the body.
• The parts of the respiratory system are:
 air passages
 lungs
 diaphragm
Respiratory system
Respiratory System
Passage of Air
• Enters the nasal cavity, here the air warms,
moistens & is filtered.
• Air then passes into the larynx
• Air is then passed down the trachea (windpipe)
• Air then moves through the bronchi (left & right
bronchus)
• Air then passes into the bronchioles
• Air then goes into the alveoli
Gaseous Exchange
Gaseous exchange
• The O² breathed in goes through the mouth or nose, down the
trachea, into the lungs and into the alveoli.
• The O² passes through the alveoli walls into the red blood cells, via
the capillaries.
• The O² joins with haemoglobin to make oxyhaemoglobin.
• The oxyhaemoglobin is used by the working body and is transported
by the circulatory system to cells needing to release energy.
• CO² is produced as a waste product
• This is converted into a gas and passes back through the alveoli
walls, via the capillaries into the blood plasma.
• Blood takes it back to the capillaries in the lungs.
• CO² passes through the capillary and alveoli walls into the alveoli.
• It is then exhaled from the body.
Mechanism of Breathing
Inspiration
Expiration
• Diaphragm pulls down
• Intercostal muscles
contract
• Air pressure is reduced
• Air is sucked through the
tubes into the lungs
• Chest expands
• Diaphragm relaxes into
its dome position
• Intercostal muscles relax
• Chest becomes smaller
• Pressure increases on
lungs
• Air is forced out
Composition of Air
Inhaled
• 79% = Nitrogen
• 20% = Oxygen
• Trace = Carbon Dioxide
Exhaled
• 79% = Nitrogen
• 16% = Oxygen
• 4% = Carbon dioxide
Definitions
Vital Capacity
The maximum amount of air that can be forcibly exhaled,
after breathing in as much as possible.
Residual Volume
The amount of air left in the lungs after a maximal breath.
Respiratory Rate
Number of breaths per minute
Tidal Volume
Amount of air breathed in or out at rest
Minute Volume
Volume of air breathed in, in 1 minute.
Respiratory System during exercise
• Tidal volume increases
• Breathing rate increases and becomes
deeper and more regular
• Heart beat increases, supplying the
demand for more O² in the working
muscles
• Gaseous exchange in alveoli increases
Respiratory System
Long-term effects of training on the
respiratory system
Endurance
• Increased training makes gaseous exchange in the alveoli
more efficient.
• Muscles are able to work at a harder level for longer
without tiring – increasing the vital capacity of the lungs.
Interval over short distances at high speeds
• New capillaries are formed, heart muscle is strengthened
and delivery of O² improves.