Download File - Science at St. Dominics

The Breathing
System
Why breathe?
 We get oxygen by breathing it in
through our lungs.
 By burning food with oxygen in
our cells we make ENERGY
[respiration].
The Breathing system
Nasal cavity
Buccal Cavity
Pharynx (throat)
Epiglottis
Larynx (voice box)
Trachea
Ribs
Intercostal muscle
Bronchus
Bronchiole
Alveoli
Diaphragm
Part of system
Function (job)
Nose
Used to take air into our bodies. Hair and
mucus in nose trap the dirt and bacteria
Trachea
Carries air to the lungs. Held open by rings of
cartilage.
Tube which carries air from the trachea to our
lungs
Thin tubes which carry air to from the
bronchus to the alveoli.
Tiny air sacs were gas exchange takes place.
Bronchus
Bronchioles
Alveoli
Intercostal
muscles
Diaphragm
move the rib cage up or down.
Ribs
Bones which form a protective cage around the
lungs.
a sheet of muscle at the base of the rib cage
LEARNING CHECK
• What is metabolism?
• What is respiration?
• Your lungs are enclosed by what parts of the
body?
• What is the function of your ribs?
• What is your diaphragm?
Protection in the breathing system
 The lining cells of the nose,
trachea and bronchi produce a
sticky mucus that traps dust and
germs.
 White blood cells in the alveoli can
engulf bacteria and foreign
matter.
microbes travelling down
the trachea within inhaled
air
ciliated cells
microbes become stuck within
the mucus
mucus being made by the ciliated cells
Elevator action
coughed out
swallowed
The alveoli.
 Each alveolus is covered in
a net of thin-walled blood
capillaries.
 Oxygen passes from the
alveolus into the blood
capillaries by DIFFUSION
 Carbon dioxide passes from
the blood capillaries into the
alveolus by DIFFUSION
Adaptations of the Lungs for Gas Exchange
1. Alveoli have a large
surface area
2. Alveoli have thin walls
3. Walls of alveoli are moist
Transport of Oxygen in blood
• Red blood cells have the
chemical haemoglobin in
them
• Haemoglobin binds to
oxygen and carries it around
the body in the blood.
Transport of Carbon Dioxide
• Carbon dioxide is carried in the blood,
dissolved in plasma
Part of air:
Inhaled air
Exhaled air
Oxygen
21%
16%
Carbon dioxide 0.4%
4%
Water vapour
Variable
Nitrogen
78%
More than
inhaled air
78%
• Animation of air coming into the lungs
Exercise and breathing
1. Come up with a hypothesis
2. Design an experiment – control, fair
testing
3. Carry out experiment
4. Collect data and analyse it
5. Come up with some conclusions – was
your hypothesis supported?
The Effect of Exercise
Heart
rate/min
225
Breathing
rate/min
Rest
Exercise
Recovery
100
175
75
125
50
75
25
5 mins
10 mins
15 mins
20 mins
 the Intercostal muscles
and diaphragm
contract
 The ribs are pulled up
and out, and the
diaphragm flattens
downwards;
 the volume of the chest
increases, so air
pressure
drops and more air is
drawn into the lungs
and alveoli.
Click on the ‘Air Drawn in’ buttons to explore the
animation
 The Intercostal muscles
and diaphragm relax
 The ribs are pushed
down and in , and the
diaphragm travels
upwards.
 The volume of the lungs
decreases so air pressure
increases
 air is pushed out from
the alveoli.
Click on the ‘Passage of air’ buttons to explore the
animation
Mechanism of breathing
Bell Jar Model
Role of the Brain in Breathing
• Mostly breathing rhythm is unconsciously set by
the brain
• We can voluntarily change the rate at which we
breath
• You can’t hold your breath forever
• Your brain won’t let you
 We breathe
automatically by
involuntary reflex
action. It is
controlled by the
brain.
 The rate of breathing is continually adjusted to meet the body’s
needs (an example of homeostasis).
Higher Level only
 Receptors (nerves) in the brain are sensitive to changes in the
CO2 concentration of the blood.
If we are exercising,
 a rise in the CO2 levels in the
blood results in the brain
sending impulses to the
diaphragm and intercostal
muscles,
 causing an increased rate of
contraction and deeper
inspiration.
ASTHMA
Asthma is when the bronchioles are narrowed – making
it difficult to inhale enough oxygen.
http://www.abpischools.org.uk/lib/liInteractiveAnim/195/asthma_
attack.swf
Asthma: Causes
•Pollen
Animals
Smoke
•Exercise
Dust mites
Asthma -- Prevention and Treatment
•Identify triggers
-- avoid or remove
•Use specific drug
treatments
•Bronchodilators
•http://www.abpischools.org.uk/lib/liInteractiveAnim/205/salbutamol3.swf