Lungs as an exchange organ

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  • Created by: Steff06
  • Created on: 08-04-16 12:31
Describe the route the air takes through the lungs
Trachea, bronchi, bronchioles, alveoli.
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What is gaseous exchange?
The movement of gases by diffusion between an organism and its environment across a barrier such as the alveolus wall.
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Describe the passage of oxygen and carbon dioxide in the lungs
Gases pass both ways through the thin walls of the alveoli. Oxygen passes from the air in the alveoli to the blood in the capillaries. Carbon dioxide passes from the blood to the air in the alveoli.
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How are the lungs adapted for exchange?
Large surface area, a barrier permeable to oxygen and carbon dioxide, thin barrier to reduce diffusion distance, maintaining the diffusion gradient.
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How does a large surface area help with exchange?
Provides more space for molecules to pass through.
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How does a thin barrier help with exchange?
Reduce diffusion distance as alveolus wall and capillary wall are one cell thick and walls consist of squamous cells. Capillaries in close contact with alveolus wall, capillaries are narrow so red blood cells squeezed against wall making them closer.
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How does a barrier permeable to oxygen and carbon dioxide help with gaseous exchange?
Readily allow diffusion of oxygen and carbon dioxide.
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How does maintaining the diffusion gradient help gaseous exchange?
For diffusion to be rapid,a steep diffusion gradient is needed.High conc of molecules on the supply side + low conc on demand side.Fresh supply of molecules on 1 side needed to keep conc high,way of removing molecules from other side keeps conc low.
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What must the lungs produce to reduce cohesive forces between water molecules and what would happen without it?
Produce a surfactant. Without it, alveolus wold collapse due to cohesive forces between water molecules lining the air sac.
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What is this achieved by?
Action of the blood transport system and the ventilation movements.
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Describe the role of blood in exchange of CO2 and oxygen
Blood brings CO2 from tissues to lungs to ensure conc of CO2 in blood is higher than that in air of alveoli. Carries oxygen away from lungs to ensure conc of oxygen in blood is kept lower than conc in air in alveoli.
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Where does the heart pump blood?
Pumps blood along pulmonary artery to lungs. in the lungs, artery divides up to form finer vessels which carry blood into finer capillaries.
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What do the breathing movements of the lungs do?
Ventilate the lungs and replace the used air with fresh air. Brings more oxygen into lungs+ensures conc of oxygen in air of alveolus remains higher than conc in blood.
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What does ventilation do?
Removes air containing CO2 from the alveoli which ensures conc of CO2 in alveoli remains lower than that in the blood.
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What does constant supply of gas to 1 side of exchange surface and removal from other side ensure?
Ensures diffusion and exchange can continue.
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Other cards in this set

Card 2

Front

What is gaseous exchange?

Back

The movement of gases by diffusion between an organism and its environment across a barrier such as the alveolus wall.

Card 3

Front

Describe the passage of oxygen and carbon dioxide in the lungs

Back

Preview of the front of card 3

Card 4

Front

How are the lungs adapted for exchange?

Back

Preview of the front of card 4

Card 5

Front

How does a large surface area help with exchange?

Back

Preview of the front of card 5
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