Download 2.-the-lungs-respiratory-system

National 5 Biology
Key Area 6:
The Need for Transport
(b) Animal Transport Systems
National 4 Biology
Key Area 4
Growth and Development of
different organisms
By the end of this lesson you will
be able to ....
• Name the different parts of the respiratory
system
• Describe the function of rings of cartilage in
the airways
• Describe the structure of the alveoli
• Describe the self-cleaning mechanism present
in the lungs.
Structure of the Lungs
• Windpipe (trachea)
• Has rings of
cartilage around it
• These rings help to
keep the windpipe
open!
Structure of the Lungs
• Bronchi
(plural)
• Bronchus
(singular)
• Connects the
windpipe to
the lungs
• Also contains
cartilage
Structure of the Lungs
• Bronchioles
• Smaller
tubes which
branch out
throughout
the entire
lung
• End in air
sacs
Structure of the Lungs
•
•
•
•
Air sac (alveolus)
SITE OF GAS
Air sacs (alveoli)
EXCHANGE!
As small as a grain of salt!
Completely surrounded by blood capillaries
http://www.footprintsscience.com/flash/Alveoli.swf
TASK: label your diagrams
Structure of the Lungs
•
•
•
•
•
•
WORD
BANK:
Trachea
Bronchus
Bronchiole
Alveoli (Air
sacs)
Lung
Rings of
cartilage
Air sacs are covered with blood capillaries
Oxygen
enters the
blood
Carbon
dioxide
leaves the
blood
Bronchioles
Air sacs
A single air sac
Each air sac is a
hollow, thin-walled
sac that is covered with
Capillaries.
This is where gas
exchange takes place
in the lungs
Gas Exchange in an Alveolus
Oxygen and carbon dioxide are exchanged through the
alveolar walls
Deoxygenated
blood enters
Alveolus is ONE CELL THICK
Alveolus
(air sac)
CO2 out
Dense blood
capillary network
O2 in
Layer of moisture
oxyhaemoglobin
Oxygenated
blood leaves
Alveolus
HIGH
CONCENTRATION
of CO2
LOW
CONCENTRATION
OF CO2
HIGH
CONCENTRATION
O2
Blood capillary
LOW
CONCENTRATION
of O2
Why are the alveoli so good at
Gas Exchange?
1. Alveoli have a large surface area
2. Alveoli have thin walls (only 1 cell thick!)
3. Alveoli have a good blood supply (surrounded
by a dense network of blood capillaries)
All of the above allow for more efficient
diffusion of gases.
Diffusion is the movement of a substance from
an area of high concentration to an area of low
concentration
Add the arrows to your diagram!
Add the arrows to your diagram!
HIGH
CONCENTRATION
of CO2 in blood
LOW
CONCENTRATION
OF CO2
HIGH
CONCENTRATION
O2
LOW CONCENTRATION
of O2 in blood
Diffusion of Gases in the alveolus
• There is a high concentration of carbon
dioxide in the blood capillary and a low
concentration in the alveolus, SO carbon
dioxide will diffuse OUT of the blood
capillary and INTO the alveoli
• There is a high concentration of OXYGEN
in the ALVEOLUS and a low concentration
in the BLOOD CAPILLARY, so OXYGEN
will diffuse OUT of the ALVEOLUS and
INTO the BLOOD CAPILLARY
Healthy lungs!
How are the
lungs kept clean?
MUCUS
•Why are the lungs
‘shiny’ looking?
•Are the lungs wet
or dry?
•What makes them
like this?
Mucus
• Mucus is a sticky substance that lines our
respiratory tract
• It traps dirt particles and micro-organisms
like bacteria and some viruses
Microscope Slides Of Cilia
light microscope slide
(X1000)
electron microscope slide
X500,000
movement of cilia
Cilia
hairs
Special features of the lungs
• Rings of Cartilage
– This helps to keep the main airways
(trachea and bronchi) open and prevent
them from collapsing
• Mucus and Cilia
– These help to keep the lungs clean
– Mucus traps dirt and microorganisms and
the rhythmic movement of the cilia beat
the mucus up and away from the lungs
Stick in your diagram!
How do the lungs keep
themselves clean?