Introduction to the respiratory system

1. Respiratory System

2. Respiratory System
O Why is the respiratory system important??
O What makes up the respiratory system?

3. Respiratory System
O In pairs you have a blank respiratory system.
O You need to label the respiratory system
Naso-pharynx (nasal cavity), ribs, pharynx, trachea, alveoli, lungs, nose,
diaphragm, larynx, bronchioles, bronchi, intercostal muscles (internal and
external) and mouth.

5. Ribs
Bronchus
Lung
Diaphragm
Trachea
(wind
pipe)
Alveoli
Bronchioles
Intercostal
muscles
(internal – lie inside
ribcage; external – lie
outside of ribcage)

6. Respiratory System
O Now you know where all the parts of the
respiratory system are you need to research
what each part does.

7. Upper Respiratory Tract
■ Nasal Cavity
■ Warms
■ Filters
■ Moistens
■ Epiglottis
■ Separates the food
pipe and trachea.
■ Pharynx
■ Is the throat and the
passage way for food
and air.
*

8. Respiratory System
■ Trachea (windpipe): travels down
the neck in front of the
oesophagus and is 12cm long by
2cm diameter.
■ Bronchi (plural): two tubes
branching form the trachea into
the lungs. The air at this point is
warm, clear and saturated with
water vapour.
■ Once inside the lung the
bronchus subdivides into lobar
bronchi (2nd order bronchus). 3
on the right and 2 on the left.
■ Lobar bronchi (3rd order
bronchus) then branch into
segmental bronchi.
*

9. *
Right lung
Left lung
Pulmonary artery
Trachea
Superior vena
cava
Heart
Bronchus
Aorta
The lungs are slightly different sizes and shapes. The
right lung is the larger, and is divided into three separate
parts. The smaller left lung is in two parts. In an adult,
the two lungs together weigh about 1kg.

10. Bronchioles and Alveoli
■ Bronchioles: smaller
branches of the bronchi and
are 1mm in diameter.
■ Alveoli – These are
responsible for the gaseous
exchange between the lungs
and the blood.
■ The walls of the alveoli
are thin with a film of
water which allows the
dissolving of oxygen
from inspired air.
*
Alveoli

11. *
THE ALVEOLI
■ The sacs look like bunches of
grapes at the end of the bronchial
tubes.
■ The alveoli are where the oxygen
from the air enters your blood,
and the carbon dioxide from your
body goes into the air.
■ Alveoli are very tiny, you have 300
million alveoli in each lung.
■ Enormous area for gaseous
exchange – roughly a size of a
tennis court.
McGuiness, H. (2006)

12. Pleural Membrane
■ The lungs are
surrounded
membranes called
pleura.
■ In between the
membranes is a fluid
called pleural fluid
which lubricates the
surfaces of the lungs
and the chest wall.
*

13. *
Functions of the
Respiratory System?

14. *
Functions of the
Respiratory System
■ Gaseous exchange
■ Mechanisms of breathing
■ Inspiration
■ Expiration
■ Lung volumes
■ Control of breathing.

15. Functions of the respiratory system
The Exchange of Gases within the Lungs
■ Within the lungs, we have alveoli (situated at
the end of bronchioles) – these are air sacs which
are large enough so that gaseous exchange can take
place
■ Gaseous exchange will take place when we
breathe oxygen in
■ This will be transported to our alveoli where it
will be exchanged with carbon dioxide
■ The oxygen will then be transported around
the body for use

16. *
Gaseous Exchange
■ Diffusion of
oxygen into
the blood
stream.
■ Diffusion of
carbon
dioxide out
of the blood
stream.
McArdle, W. et al (2000)

17. Alveoli
Alveoli are extremely tiny structures in the lungs where the
exchange of oxygen and carbon dioxide takes place.
■ Their walls are very thin
and moist to help oxygen and
carbon dioxide pass through.
This process is called
diffusion.
■ The bunches of alveoli are
surrounded by a dense
network of capillaries.
■ The capillaries also have very
thin walls, which again help the
diffusion of oxygen and carbon
dioxide into and from the
blood.
A Single Alveolus
Capillaries
Red Blood Cells
Thin wall,
one cell thick

18. How the Alveoli and Capillaries Work
1. Air containing oxygen
enters the lungs and
passes into each
alveolus from outside.
2. Deoxygenated blood
containing carbon
dioxide comes from
the rest of the body.
■ Oxygen is
diffused
into the blood
from
the alveoli.
■ Carbon dioxide
is
diffused from
the blood into
the alveoli.
■ The blood
becomes
oxygenated.

19. 3. Air containing more
carbon dioxide
leaves
the lungs.
4. The oxygenated
blood leaves the lungs
and is transported by
the circulatory system
for use throughout
the body.
How the Alveoli and Capillaries Work

20. The Mechanics of Breathing
Breathing in (inspiration) and breathing out
(expiration) are mechanical processes
involving the ribs, intercostal muscles and
the diaphragm.
External
intercostal
muscles
Internal
intercostal
muscles
The intercostal muscles
are antagonistic - the contraction
of the external muscles raises
the rib cage, whereas contraction
of
the internal muscles
lowers the rib cage.
The diaphragm is a
powerful sheet of muscle
that separates the chest
from the abdomen; it is
dome-shaped when relaxed
and flattens on contraction.
Diaphragm
Ribs

21. Inspiration - Breathing In
When inhaling…
■ The intercostal muscles contract
and pull the rib cage up and out.
■ The diaphragm
contracts
causing it to flatten.
■ The chest cavity gets
larger causing pressure
in the lungs to fall.
■ Air moves into the
lungs
from the higher
outside pressure.
Air
flowing
in

22. ■ The chest cavity gets
smaller and so pressure
in the lungs increases.
When exhaling…
Expiration - Breathing Out
■ The intercostal muscles relax
and so the rib cage returns
to normal.
■ The diaphragm relaxes
pushing it up.
■ Air flows out of the lungs.
Air
flowing
out
During periods of increased activity
the rate and depth of breathing increases due to an
increased demand of oxygen

23. *
Inspiration and
Expiration
Inspiration:
■ About 79% nitrogen
■ About 21% oxygen
■ Tiny amount of carbon
dioxide (0.04%)
■ Water vapour
■ Dust, air pollen, germs,
poisonous gases
Expiration:
■ About 17% oxygen
■ About 79% nitrogen
■ 3% carbon dioxide
■ A lot of water vapour

24. Common Terms

25. *
How Much Air do you
Breathe?
■ The respiratory rate is the number of breaths an
individual takes per minute.
■ Tidal volume can be described as the amount of air
breathed in and out with each breath.
■ At rest – 500cm3 of air:
■ Two thirds (350cm3) reaches the alveoli for
gaseous exchange.
■ The remainder fills the pharynx, larynx,
trachea, bronchi and bronchioles (150cm3).
Known as dead or stationary air.
■ The minute volume is the volume of air an individual
breathe in per minute.

26. *
Rest versus Exercise
Minute Volume (MV) = Tidal Volume (TV) x Breathing
Rate (BR)
At rest
■ MV = 0.5 litres x 12 breaths per minute = 6 litres per
minute
During exercise
■ MV = 2.5 litres x 30 breaths per minute = 75 litres per
minute.

27. *
■ Inspiratory reserve volume - maximum
inspiration at end of tidal inspiration.
■ 3 litres of fresh air breathed in as
well as the tidal volume.
■ Expiratory reserve volume – maximum
expiration at end of tidal expiration.
■ An additional 1.5 litres breathed out
after normal expiration.

28. *
Lungs Capacity
■ Vital capacity is the maximum of air an individual can
breathe out as deeply as they can. It is usually about
4.8 litres.
■ Residual volume is the amount of air an individual has
in their lungs after they breathe out as hard as they
can. It is usually about 1.2 litres.
■ Total lung capacity: after an individual has inhaled as
deeply and as maximally as they can.
Total lung capacity (6 litres) = vital capacity +
residual volume.

29. There are 6 key terms you need to understand…
■ Tidal Volume – amount of air breathed in
and out with each breath
■ Inspiratory reserve volume – deep
breathing allows you to take in more air than
usual so that it reaches the alveoli
(particularly important when exercising
Breathing - Key Terms
■ Expiratory reserve volume – additional air
breathed out after normal expiration
■ Vital Capacity – maximum air breathed out
with force
■ Residual Volume – air that remains in the
lungs as the lungs will never be empty
■ Total lung capacity – when breathing in as
deep as possible this is total volume of gas in lungs

30. *
Respiratory Volumes –
Graph, Label each
number?

31. Respiratory Volumes –
Graph.
*

32. *
Control of Breathing
Neural control:
■ Involves neurones, cells that conduct
nerve impulses, in the reticular
formation and pons, both parts of the
brain stem. Neurones in two areas of
the medulla are critical for respiration.
These are the dorsal respiratory (DRG)
and the ventral respiratory group
(VRG). The VRG is thought to be
responsible for the rhythm generation.

33. *
Chemical control:
■ Carbon dioxide and oxygen
are always changing levels.
Sensors responding to such
chemical fluctuations are
called chemoreceptors. These
are found in the medulla and
in the aortic arch and carotid
arteries.

34. Research Effects of
Exercise

35. Research Effects of
Exercise
O Increased TV (lower respiration rate at rest and submaximal
levels)
O Less breaths at submaximal levels, air stays in the lungs
longer, allowing more o2 extraction
O Increased ventilation at maximal levels
O Decreased use of o2 by respiratory muscles such as the
diaphragm frees o2 for use by other skeletal muscles involved
in exercise
O Alveolar-capillary surface area increases resulting in
increased pulmonary diffusion - more o2 is absorbed by red
blood cells