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Learning Objectives• Can you label a diagram of the thorax, including the
ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes?
• Can you explain how the intercostal muscles and the diaphragm are used in ventilation?
• How is diffusion involved with gas exchange?• Can you explain how alveoli are adapted for gas
exchange?• What kind of experiment could you do to investigate
the effect of exercise on breathing rate in humans?
Copyright © 2014 Henry Exham
The Gaseous Exchange System
Pleural membranes
Bronchi
Bronchiole
Alveoli
Ribs
Intercostal muscles
Lungs
Nose
Mouth
Trachea
Diaphragm
Copyright © 2014 Henry Exham
Structure Function
Trachea Tube with incomplete rings of cartilage carries air to lungs; lined with cells making mucus, and cells with cilia to move the mucus away.
Bronchi Carries air to lungs
Bronchioles Carry air to lungs
Alveoli Tiny air sacs adapted for gas exchange
Diaphragm Sheet of muscle with a fibrous middle part which is domed; it helps make breathing movements and separates the thorax from the abdomen
Ribs Bones that protect and ventilate the lungs
Intercostal muscles Move ribs for ventilation
Pleural membranes Thin moist membranes forming an airtight seal around the lungs and separating inside of thorax from lungs
The Gaseous Exchange SystemCopyright © 2014 Henry Exham
Ventilation of the lungs• Ventilation means moving air in and out of the
lungs.• This requires a difference in air pressure and
relies on the thorax being an airtight cavity.• Movements of the intercostal muscles and
diaphragm change the volume inside the cavity and therefore the air pressure.
• This causes the air to move in or out.
Copyright © 2014 Henry Exham
Inhalation
∂∂
∂∂
∂∂
Side view of thorax
Diaphragm
Lungs
Ribs
Intercostal muscles
Copyright © 2014 Henry Exham
Inhalation
∂∂
∂∂
∂∂
1
2
3
4
5Intercostal muscles contract
Ribs pulled up and out
Diaphragm contracts and flattens
Volume of thorax increases which reduces the pressure.
Therefore air moves into lungs.
Copyright © 2014 Henry Exham
Exhalation
∂∂
∂∂
3
4
Diaphragm relaxes and returns to dome shape.
Volume of thorax decreases which increases the pressure.
Therefore air forced out of lungs.
51
2
Intercostal muscles relax
Ribs move down and in
Copyright © 2014 Henry Exham
Gas exchange in the alveoli• The lungs contain 700,000,000 tiny air sacs called
alveoli.• They are surrounded by a network of blood capillaries. • Carbon dioxide diffuses from the blood into the air in
the alveoli. • Oxygen diffuses from the air in the lungs into the
blood.• The oxygenated blood then travels back to the heart to
be pumped around the body.
Copyright © 2014 Henry Exham
Structure of the alveoli• Each alveoli is surrounded
by blood capillaries. • These carry deoxygenated
blood.• The carbon dioxide that is
carried by the blood diffuses into the alveoli to be exhaled.
• The oxygen diffuses into the blood from the alveoli and binds to the red blood cells.
air in and out
Oxygen
Carbon dioxide
Oxygenated blood
Deoxygenated blood
Red
bloo
d ce
ll
Capillary
Copyright © 2014 Henry Exham
Adaptations of the alveoli• They have a large surface area for diffusion.• Fluid to help dissolve gases and increase diffusion rate.• A rich blood supply to maintain a steep diffusion
gradient between the alveoli and the blood.• Due to both the alveoli and the capillary only having
walls one cell thick there is a short diffusion distance between the air and the blood which increases diffusion rate.
Copyright © 2014 Henry Exham
Exercise and BreathingWhat I know What I want to know What I learned
Investigate the effect of exercise on breathing rate.
• It is also interesting to see what happens to breathing rate immediately after exercise.
Click on the above image to see some typical results for a normal and fit person.
Copyright © 2014 Henry Exham
Investigate the effect of exercise on breathing rate.
• First you must determine your resting breathing rate.
• Count how many times you inhale in a minute.• Do this three times and take an average. • This will make your data more reliable.
Copyright © 2014 Henry Exham
Investigate the effect of exercise on breathing rate.
• Then you must calculate your breathing rate carrying out exercise.
• Jog on the spot for one minute and count the breaths you inhale in that time.
• Then take a minute to rest.• Once again repeat the experiment two more times and take the average of all three results.
Copyright © 2014 Henry Exham
Investigate the effect of exercise on breathing rate.
• You should find that breathing rate increases as you exercise.
• This is to provide your muscles with more oxygen which it can use for aerobic respiration to release energy.
Copyright © 2014 Henry Exham
The question I am investigating is………..
My independent variable (what I am changing) is…
We will change our independent variable by….I plan to test these values/this range…..because….
My dependent variable (the one I am measuring) is…
I will measure my dependent variable by….
The units I will measure it in are…
The variables I will need to control (keep the same) are…..
I will keep these variables the same, to make it a fair test, in this way….
Variables that I might not be able to control properly are…Because…
I predict that….
Because….
The step-by-step method I plan to follow is…
1.
2.
Method is in correct orderMethod contains more than one approach
Diagrams to help explain the method….
Labelled, detailed, accurate
The safety features of my experiment are….
The reasons I need these safety features are…
To make my investigation experiment reliable I will….
More than one suggestion
My results table will look like this….
Have included units
The equipment I need for this experiment is….
Sizes/ details /correct equipment names
The scientific knowledge we have used to make our prediction is…
DETAIL! JUSTIFY YOUR METHOD! NAME YOUR SOURCESB
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B
M/H
M
M
M
B
B
B
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BIOLOGYI am hoping to find out……….. M
H
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B
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Final Product• You are a qualified G.P. and you have a patient that has been
diagnosed with a mild case of emphysema. The patient is a smoker and is reluctant to stop because they think it’s cool. Create an informative and persuasive argument to present to your patient next time you see them.– The chemicals in smoke and their effects on the body– Emphysema – short and long term effects– Other effects of smoking e.g. lung cancer and coronary heart diseaseYou may work in pairs or individually and present your argument how you wish e.g. presentation, poster ...You must have a printed version for your exercise book or as a classroom display.
DUE MONDAY OCTOBER 12.