The Respiratory System
Effects of Acute & Long Term Exercise
• P1 – U1
• A4 not A5
• Key Verbs & Spelling/Punctuation – Donkey
• Effects of Exercise
• Wider Reading
• Specification
• Put Old Work in For Submission as Well
Nasal Cavity
Lobes - 3 on
Right & 2 on
Thoracic Cavity – Chamber of
chest protected by the
thoracic wall. Separated from
abdominal cavity but
Visceral Pleura
The visceral pleura is the innermost of the two
pleural membranes. It covers the surface of
the lung and dips into the spaces between the
Pleural Fluid
The pleural membrane produce pleural fluid which fills the space
between them. This acts a lubricant to allow to glide over the
thoracic wall during respiration
Whilst membranes slide easily over each other, their separation
is resisted by the surface tension of the pleural fluid that keeps
the lung surface in contact with the chest wall
Gaseous Exchange
• This happens by a process called DIFFUSION.
• DIFFUSION is the name given to the process of exchanging gases in
the tissues in the body
Diffusion Is When –
• Air comes into the body
• Oxygen separated out and passed around the body.
• Carbon dioxide removed and expelled.
• This happens every time you breathe.
• The blood in these capillaries passes its
carbon dioxide into the capillaries before
taking in oxygen from the alveoli.
• Alveoli ---------oxygen-----------capillaries
• Whilst the oxygen is taken in, carbon dioxide is
given out into the alveoli and breathed out.
Mechanisms of Breathing
Breathing is when air transported in and out of
the lungs, and can be split into two phases
Inspiration & Expiration
Within inspiration the intercostals muscle contract
to lift the ribs upwards and outwards, while the
diaphragm is forced downwards and the sternum
This expansion of the thorax in all directions causes
a drop in pressure which encourages air to flood
into the lungs. At this point oxygen is exchanged
for carbon dioxide through the capillary walls
Expiration follows inspiration as the intercostals
muscles relax, the diaphragm extends
upwards and the ribs and sternum collapse
At that point, pressure within the lungs is
increased and air is expelled. When the body
is in action, greater amounts of oxygen are
required, meaning the intercostal muscles and
diaphragm need to work harder
Lung Volumes
Respiratory Rate – Amount you can breathe in in one
Equal to approx 12 BPM = 6 Litres of air passes through
During exercise = 30 – 40 BPM
Other measurements include, Tidal Volume, Inspiratory &
Expiratory Reserve Volume, Vital Capacity, residual
Volume, Total Lung Capacity, Chemical Control
Tidal Volume
Tidal volume is the lung volume representing
the normal volume of air displaced between
normal inspiration and expiration when extra
effort is not applied. Typical values are around
500ml or 7ml/kg bodyweight
Mechanisms of Breathing
The volume of air which you normally breathe in and out is called the tidal volume. This is
normally about 500 cm3 when you are at rest
However if you breathe in as much as you can you can breathe in more than 500 cm3. The
extra volume of air breathed in (inspiration) is called the inspiratory reserve volume
Similarly when you breathe out as much as you can, the extra volume of air breathed out
(expiration) is called the expiratory reserve volume
These three volumes added together give you your vital capacity: the maximum volume of
air you can breathe in or out
When you have breathed out as much as you can there is still some air left in your lungs i.e.
you cannot empty your lungs completely. This volume is called the residual volume
The vital capacity plus the residual volume equals your total lung capacity
Vital Capacity
Vital Capacity is the amount of air that can be
forced out of the lungs after maximal
inspiration. The volume is around 4,800cm3
Residual Volume
The amount of air remaining in the lung at the
end of a maximal exhalation
Control of Breathing – Neural &
Chemical Control
Breathing rate is primarily regulated by neural and chemical mechanisms. Respiration is
controlled by spontaneous neural discharge from the brain to nerves that innervate
respiratory muscles. The primary respiratory muscle is the diaphragm, which is innervated by
the phrenic nerve. The rate at which the nerves discharge is influenced by the concentration
of oxygen, carbon dioxide and the acidity of the blood
Chemical Control
There are chemoreceptors in the brain and the heart that sense the amount of oxygen,
carbon dioxide and acid present in the body. As a result, they modulate the respiratory rate
to properly compensate for any disruptions in balance of any of these chemicals. Too much
carbon dioxide or acidity and too little oxygen cause the respiratory rate to increase and vice
versa. Carbon dioxide chemoreceptors are much more sensitive than oxygen chemoreceptors
and, thus, exert an effect with smaller changes.
Neural Control
There are two neural mechanisms that govern respiration -- one for voluntary breathing and
one for automatic breathing. The voluntary impulse originates in the cerebral cortex region of
the brain and the automatic impulse originates in the medulla oblongata.