Respiratory system (MYP3)
Efficient gas exchange in the
human respiratory system
Unit 3: Out with the old and in with the new: exchange systems.
Grade level: MYP 3 (grade 9)
Lesduur is: 45 minOnderdelen in deze les
Efficient gas exchange in the
human respiratory system
Unit 3: Out with the old and in with the new: exchange systems.
Grade level: MYP 3 (grade 9)
Lesson objectives
At the end of this lesson you can:
Outline four conditions needed for efficient gas exchange in the human respiratory system.
Describe the relationship between form and function in the human respiratory system.
Explain the effect of asthma on the function of the human respiratory system.
Why do you think people with asthma struggle to breath during an asthma attack?
In your lungs, gases are exchanged with the air you inhaled.
Which gas needs to go out of your body, and which gas needs to go into your body?
What needs to go IN?
What needs to go OUT?
Nitrogen
Carbon dioxide
Carbon mono-oxide
Oxygen
Conditions for gas exchange
For efficient gas exchange between the air and your blood, several conditions need to be met. Today, you will learn what these conditions are and how form meets function!
We are not stirring the water and the glasses are standing still. Do you think the yellow dye will fully mix with the water?
Yes, the dye will fully mix.
No, the dye will not fully mix.
In what direction does the dye move?
From low to high concentration
From high to low concentration
Condition 1: Big concentration gradient
Because your body uses a lot of oxygen, the O2 concentration in the air is higher and the oxygen moves into your lungs through diffusion.
Because your body produces a lot of CO2, the CO2 concentration in the air is lower and the CO2 moves out of your lungs through diffusion.
Bigger concentration gradient
→ faster gas exchange!
Which object do you think absorbs water the fastest?
Flat sheet of paper
Crumpled paper
Sponge
Condition 2: Large surface area
Larger surface area
→ faster gas exchange.
Your lungs have about 300-500 million alveoli, all covered with capilaries. This creates an extremely large surface area for gas exchange between the air and your blood.
Condition 2: Large surface area
Larger surface area
→ faster gas exchange.
Connection: do you remember the folds in small intestine to create a large surface area earlier in this unit?
Form: lot of vesicles or folds to create a large surface area.
Function: efficient exchange of gases (lungs) or nutrients (small intestines).
Do you think a thin or a thick wall allows for faster diffusion of gases between the lungs and the blood?
Thin wall
Thick wall
Condition 3: Thin exchange area
Thinner exchange area
→ faster gas exchange!
A thin exchange barrier makes it is easier for CO2 to move out and for O2 to move into the bloodstream.
Both the lung alveoli and the blood capillaries are only one cell thick! This thin layer between your blood and the air makes gas exchange very efficient!
Condition 3: Thin exchange area
Thinner exchange area
→ faster gas exchange!
Connection: in your digestive system, the wall of the small intestines is also one cell thick. So this thin layer of one cell only allows for efficient exchange of gases in your lungs and nutrients in your small intestines.
Form: one cell thick
Function: efficient exchange of gases.
What is the function of the diaphragm and the intercostal muscles in the respiratory system?
They increase and decrease the volume of the chest cavity to allow breathing.
They open the airways to allow more air to flow inside the lungs during excersise.
Condition 4: Continuous air flow
More air flow
→ faster gas exchange!
Breathing is the process that allows fresh air into the lungs, and keeps up the concentration gradient for gas diffusion.
The faster the air flow, the more gas exchange takes place. This is why you breath faster when you need more oxygen, for example while running.
Form: rib cage that can expand and contract.
Function: continuous airflow trough the lungs.
Drag all conditions needed for efficient gas exchange in the human respiratory system to the box on the bottom right.
Efficient gas exchange system
Large concentration gradient
Continuous air flow
Small surface area
Large surface area
Thick gas exchange area
Obstructed air flow
Thin gas exchange area
Small concentration gradient
Now that you know the four conditions needed for efficient gas exchange in your lungs, it's time to think about how asthma affects these conditions!
Which condition for efficient gas exchange in the lungs is mostly affected by asthma?
The concentration gradient.
The surface area.
The thickness of the exchange area.
The continuous airflow.
Asthma reduces mostly the continuous flow of air through the lungs. This is the main cause of asthma symptoms !
The main problem in asthma is the
limited flow of air through the
lungs, particularly in the airways.
This has three different causes:
1. Inflamed airways swell up.
Inflamed airways produce mucus.
Smooth muscles of airways are tightened.
→ This makes the airways more narrow, and blocks the airflow towards the lungs.
Does it affect the other conditions too?
Mostly not, because the alveoli and the capillary are both only 1 cell thick. However, in some severe cases of chronic asthma, fluid can build up between the alveoli and the capillaries.
Concentration gradient:
Yes, asthma reduces the concentration gradient, because blocked airways allow less fresh air to reach the lungs.
Surface area:
No, people with asthma have the same amount of lung alveoli as other people, so the surface area is the same.
Thickness of exchange area
An asthma attack can be life threatening, and treating a patient with the right medicines can save lives.
How do you think a reliever inhaler works?
It provides medicines that reduce the inflammation and open up the airways.
It provides cold air that reduces inflammation and open up the airways.
It provides medicines that help to relax the smooth muscles and open up the airways.
It provides medicines that dissolve the mucus and open up the airways.
Reliever inhalers contain bronchodilators, which help to relax smooth muscles and open up the airways.
If this doesn't work, ambulance personal has additional options to stop the attack:
Oxygen mask that provides oxygen rich air.
Higher dose of bronchodilators to relax smooth muscles.
Steroids to stop inflammation.
In some severe cases, a patient needs to go to the hospital. Here, they can place an intubation tube into the trachea to help with breathing until the inflammation has stopped.
When the ambulance arrived, Nathan received a nebulizer Mask, with a higher dose of medicine than his inhaler could provide. This helped to open up his airways. He went to the hospital for a check-up, but he was fine afterwards.
Thanks a lot for your participation!
Please share your opinion about this lesson, so I can keep improving.
To what extent did you feel engaged during the lesson?
To what extent where the explanations of the teacher clear? you?
To what extent did you learn something new today?
Anything else you would like to share?
