Back to AI Flashcard MakerBiology /Edexcel Biology GCSE - Gas Exchange in Animals Part 2
Edexcel Biology GCSE - Gas Exchange in Animals Part 2
This deck covers key concepts related to gas exchange in animals, focusing on the structure and function of the respiratory system, diffusion, and factors affecting gas exchange efficiency.
The effectiveness of exchange surfaces in plants and animals is increased by having a short distance required for diffusion:
the membranes of cells the flattened shape of structures such as leaves the walls of blood capillaries are one cell thick the epithelia of alveoli in the respiratory system and the villi in the small intestine are only one cell thick
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Key Terms
Term
Definition
The effectiveness of exchange surfaces in plants and animals is increased by having a short distance required for diffusion:
the membranes of cells the flattened shape of structures such as leaves the walls of blood capillaries are one cell thick the epithelia of alveoli in ...
In animals an efficient blood supply to transport molecules to and from the exchange surface increases effective exchange. Examples of this include:
the network of blood capillaries that surrounds each alveolus in the lungs the network of blood capillaries in each villus in the small intestine
What does the process of ventilation do?
In the lungs, the process of breathing, or ventilation, brings air to, and removes air from the exchange surface - the alveoli.
How can a steep concentration gradient be maintained?
The moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained.
The human lungs provide an exchange surface adapted for:
Absorbing oxygen - needed for respiration - into the blood from the air in the lungs Transferring carbon dioxide - produced by respiration - from the ...
Where are the lungs in the body?
The lungs are enclosed in the thorax, surrounded and protected by 12 pairs of ribs. The ribs are moved by two sets of intercostal muscles. There is a ...
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| Term | Definition |
|---|---|
The effectiveness of exchange surfaces in plants and animals is increased by having a short distance required for diffusion: | the membranes of cells the flattened shape of structures such as leaves the walls of blood capillaries are one cell thick the epithelia of alveoli in the respiratory system and the villi in the small intestine are only one cell thick |
In animals an efficient blood supply to transport molecules to and from the exchange surface increases effective exchange. Examples of this include: | the network of blood capillaries that surrounds each alveolus in the lungs the network of blood capillaries in each villus in the small intestine |
What does the process of ventilation do? | In the lungs, the process of breathing, or ventilation, brings air to, and removes air from the exchange surface - the alveoli. |
How can a steep concentration gradient be maintained? | The moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained. |
The human lungs provide an exchange surface adapted for: | Absorbing oxygen - needed for respiration - into the blood from the air in the lungs Transferring carbon dioxide - produced by respiration - from the blood into the lungs (which then goes into the air) |
Where are the lungs in the body? | The lungs are enclosed in the thorax, surrounded and protected by 12 pairs of ribs. The ribs are moved by two sets of intercostal muscles. There is a muscular diaphragm below the lungs. The lungs are sealed within two airtight pleural membranes. These wrap around the lungs and line the rib cage. |
What is the human respiratory system adapted to do? | The human respiratory system is adapted to allow air to pass in and out of the body, and for efficient gas exchange to happen. |
Structure of the trachea | The trachea, or windpipe, branches into two bronchi - one bronchus to each lung. Rings of cartilage in the walls of the trachea help to keep it open as air is drawn in. |
Structure of the bronchi | The bronchi split into smaller branches and then into smaller tubes called bronchioles. Each bronchiole ends in a cluster of microscopic air sacs called alveoli. |
Where does gaseous exchange take place? | The exchange of gases occurs between the alveoli and blood in the capillaries that supply the lungs. |
The alveoli are adapted to provide a very large surface area for gaseous exchange: | small size: each alveolus is a small sphere about 300 μm in diameter, giving it a larger surface area to volume ratio than larger structures number: there are around 700 million alveoli - ie 350 million per lung the total surface area of the alveoli is around 70 m2 - capillaries cover 70 per cent of the surface of the alveoli |
Gaseous exchange | diffusion | There is also a short diffusion path - the walls of blood capillaries and alveoli are just one cell thick. The alveoli are also lined with a thin film of moisture. Gases dissolve in this water, making the diffusion path even smaller. |
Gaseous exchange | ventilation | The ventilation of the lungs and the blood flow through the surrounding capillaries mean gases are being removed continually, and steep concentration gradients are set up for gases to diffuse. |
The rate of diffusion depends on three factors: | distance concentration gradient surface area |
How distance effects the rate of diffusion. | If the diffusion distance is small, diffusion happens faster because the particles do not have as far to travel |