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0:00
Hello, I'm Jeremy Ward,
Emeritus Professor for
Respiratory Cell Physiology
at King's College London.
I was Head of the Department
of Physiology for
ten years and for two years was
Head of the Department of asthma,
Allergy and Lung Biology.
I'm going to be talking about
the respiratory system.
0:21
The topics I'm going
to cover include,
what is the respiratory system?
Why is it important?
The carriage of O_2 and CO_2
because that is one
of the main functions
of the respiratory system.
Basic structures and functions,
the process of breathing,
the mechanics of breathing,
and the control of breathing.
I'm going to finish off with
a very brief introduction
to some common diseases of
the respiratory system.
Before we go on, just
note that PO_2 or PCO_2
denotes the partial
pressure of that gas.
In other words, the
pressure that gas exerts
as a proportion of
atmospheric pressure.
If atmospheric
pressure is 100 kPa
and air contains 21%
O_2, the PO_2 is 21 kPa.
Note that confusingly,
by convention
blood pressure is
still expressed in
millimeters of mercury
(mmHg), not SI units.
1:25
What is the respiratory system?
You can see a cartoon of
the major components.
It includes a series
of conducting airways
which carry air from the
mouth, nose to the lungs,
which is where, of
course, gas exchange
of O_2 and CO_2 occurs.
The right side of
the heart pumps
deoxygenated blood from
the veins and tissue
through specialised blood
vessels in the lung
(called the pulmonary
circulation),
to enable gas exchange,
before returning the
reoxygenated blood
to the left side of the heart
for pumping around body
and to the respiring tissues.
The respiratory
system also includes
the muscles that
enabled breathing,
including, most
importantly, the diaphragm
and the intercostal
muscles between the ribs.
