Exchange and transport
- Created by: Freja
- Created on: 08-04-21 18:52
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- Exchange and Transport
- Reasons for Exchange Systems
- Large multicellular organisms have a small surface area to volume ratio
- Metabolic rate- multicellular organisms have a high metabolic rate
- there is a need to exchange lots of materials fast
- Cells in the centre of the organisms would not receive any materials if multicellular organisms survived on diffusion alone
- Surface Area: Volume
- The larger the surface area to volume ratio of an organism, the easier the exchange of substances by diffusion is
- Multicellular organisms have a small surface area to volume ratio, so require a gas exchange system
- Features of Efficient Gas Exchange
- Large Surface Area
- Provides a large area over which the exchange of materials can occur
- Thin Layers
- This creates a short diffusion pass for gases, increasing the speed of exchange
- Blood Supply
- Good, constant blood supply maintains a large diffusion gradient and ensures the exchanged substances are constantly moving to the area needed
- Ventilation
- Maintains the diffusion gradients, this makes the process faster and more efficient
- Large Surface Area
- Components of the Lung Volume
- Spirometer
- Measures lung volume
- A person breathes in and out of the airtight chamber, thus causing it to move up and down, leaving a trace on the graph
- Tidal Volume
- The volume of air that moves into and out of the lungs with each resting breath
- Vital Capacity
- The volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath
- Inspiratory Reserve Volume
- Maximum volume of air that you can breathe in over and above a normal inhalation
- Expiratory Reserve Volume
- The extra volume of air you can force out of your lungs over and above the normal tidal volume of air you breathe out
- Residual Volume
- The volume of air that is left in your lungs when you have exhaled as hard as possible
- Total Lung Capacity
- The sum of the vital capacity and the residual volume
- Spirometer
- Ventilation
- The pressure changes in the thoracic cavity bring about ventilation
- The rib cage provides a cage in which pressure can change to facilitate breathing
- Inspiration
- Active process
- The diaphragm moves down
- There if air flow into the lungs to equalise the pressure difference
- Expiration
- Diaphragm move up
- Air moves out of the lungs to equalise the pressure
- Reasons for Exchange Systems
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