Download 10 Respiratory System SB Powerpoint

Objectives
• By the end of the lesson you will be
able to:• Identify the gross structures of the
respiratory system;
• Describe the function of 4 of the
gross structures;
• Produce a model to demonstrate the
respiratory system.
The Respiratory System
The purpose of the respiratory system is to…
“bring the air we breathe into close contact
with the blood so that oxygen can be
absorbed and carbon dioxide removed.”
Basically it consists of:

A pair of lungs connected
to the mouth via the
trachea and bronchi.

The ribs and intercostal
muscles of the chest which
protect the lungs, trachea
and bronchi.
The Thoracic Cavity
This chest X-ray shows the organs within the thoracic cavity.
Ribs
Air-filled
lung
Position
of
the heart
Position of the diaphragm
The lungs are in the thoracic cavity
and are also protected by 12 pairs
of ribs that articulate with the
vertebrae towards the back
of the body. The sternum
(breastbone) is at the
front of the rib cage.
The portions of the ribs
that articulate with the
breastbone are made
of cartilage rather
than bone.
Sternum
Cartilage
Cartilage is softer
and more pliable
than bone and this
helps the movement
of the rib cage during breathing.
Sets of
antagonistic
muscles are found
between the ribs the intercostal muscles.
The Respiratory System
Trachea
(wind pipe)
Ribs
Alveoli
Bronchus
Bronchioles
Intercostal
muscles
Lung
Diaphragm
The trachea or windpipe is
about 10 cm long and is
supported by C-shaped
rings of cartilage to
prevent the tube from
collapsing during
breathing.
The trachea
subdivides into
the left and right
bronchus.
The bronchi are
also strengthened
by cartilage.
The two bronchi
subdivide to form
an extensive
network of
Bronchioles that
deliver air to the
gas exchange
surfaces – the alveoli.
Air enters the body through
the nasal passages and
mouth, and passes via the
pharynx and larynx
to the trachea.
Air is delivered to
the alveoli as the
trachea branches
into bronchi and
bronchioles.
A photomicrograph of a cross-section through the trachea
showing the C-shaped ring of cartilage.
C-shaped
cartilage ring
The Exchange of Gases within the Lungs

The 2 bronchi, which lead to each lung divide into many bronchioles.

These are less than 1mm in diameter and terminate in grape-like
clusters of tiny sacs called alveoli.
Thorax
Section of
lung
Single alveolus
Alveolar Tissue
A photomicrograph of a section of alveolar tissue
showing the delicate nature of the lungs and the
'one cell thick' walls of the alveoli.
The Mechanics of Breathing
Breathing in (inspiration) and breathing
out (expiration) are mechanical
processes involving the ribs,
intercostal muscles and the
diaphragm.
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 thorax from the
abdomen; it is domeshaped when relaxed and
flattens on contraction.
Two sets of antagonistic
muscles are located
between the ribs - these
are the external and
internal intercostal
muscles.
External
intercostal
muscles
Internal
intercostal
muscles
Ribs
Diaphragm
The Mechanics of Breathing
The external and
internal intercostal
muscles are responsible
for the movements of
the rib cage during
breathing.
Internal
intercostal
muscles
Rib
External
intercostal
muscles
Contraction of the
external intercostal
muscles moves the ribs
upwards and outwards
during inspiration.
Relaxation of the external intercostal muscles causes the ribs
to move downwards and inwards during expiration at rest.
Expiration at rest is a passive process. However, expiration during
periods of exercise is an active process - it involves contraction of
the internal intercostal muscles and abdominal muscles to produce
more forceful expirations.
During periods of increased activity such as exercise,
the rate and depth of breathing increases.
The more forceful,
downward and inward
movements of the rib
cage during expiration
of exercise are
achieved through the
contraction of the
internal intercostal
muscles.
As the diaphragm
pushes further into
the thorax, the
volume of the chest
cavity decreases
more significantly
and the increased
thoracic pressure
helps expiration.
At the same time,
contraction of the
abdominal muscles just
below the thorax,
pushes the diaphragm
into a more domed
position.
During periods of exercise, expiration is
forced - it is now an active process.
How we Breathe
Breathing is achieved by making the chest larger or smaller,
which results in a change in pressure within the lungs.
This forces air either in or out.
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
Expiration - Breathing Out
When exhaling…
Air
flowing
out

The intercostal muscles relax
and so the rib cage returns
to normal.

The diaphragm relaxes
pushing it up.

The chest cavity gets
smaller and so pressure
in the lungs increases.

Air flows out of the lungs.

During periods of exercise, expiration becomes an active process,
involving the forced expulsion of air.
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
Thin wall,
one cell thick
Capillaries
Red Blood Cells
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.
How the Alveoli and Capillaries Work
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.
Diffusion of Carbon Dioxide into the Alveoli
Inside Capillary
Capillary Wall
Alveolus Wall
Decreasing
concentration
concentration
concentration
gradient
gradient
gradient
concentration
Inside Alveolus
Carbon dioxide
Oxygen
Diffusion of Carbon Dioxide into the Alveoli
Inside Capillary
Capillary Wall
Alveolus Wall
Decreasing
concentration
concentration
concentration
gradient
gradient
gradient
concentration
Inside Alveolus
Carbon dioxide
Oxygen
Diffusion of Oxygen into the Capillaries
Inside Capillary
Capillary Wall
Alveolus Wall
Decreasing
concentration
gradient
concentration
Inside Alveolus
Carbon dioxide
Oxygen
Diffusion of Oxygen into the Capillaries
Inside Capillary
Capillary Wall
Alveolus Wall
Decreasing
concentration
gradient
concentration
Inside Alveolus
Carbon dioxide
Oxygen
Diffusion of Oxygen into the Capillaries
Inside Capillary
Capillary Wall
Alveolus Wall
Decreasing
concentration
gradient
concentration
Inside Alveolus
Carbon dioxide
Oxygen
The Difference between Inhaled
and Exhaled Air
Inhale
air into the lungs (%)
Exhale
air out of the lungs (%)
Oxygen 20.95 %
Oxygen 16%
Nitrogen 79%
Nitrogen 79%
Carbon Dioxide 0.04%
Carbon Dioxide 4.0%
Water vapour 0.01%
Water vapour 1%
End of Show