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Exchange of Materials I - Coggle Diagram
Exchange of Materials I
Movement of substances
Cells need oxygen for aerobic respiration, and they need to remove carbon dioxide. These gases move between cells and the environment through diffusion
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Exchange surfaces
In single celled organisms, gases and dissolved substances can diffuse directly into the cell across the membrance
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This means they need an exchange surface for efficient diffusion and a transport system to move substances between the exchange surface and the rest of the body
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Alveoli
Gas exchange in mammals
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Blood arriving at the alveoli has just returned to the lungs from the rest of the body, so has a high CO2 concentration and low oxygen concentration
There's a higher concentration of oxygen in the air than in the blood, so oxygen diffuses out of the air into the alveoli and into the capillaries
Carbon dioxide diffuses in the opposite direciton, from a high concentration in the blood to a low concentration in the alveoli
Adaptations
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Moist lining from dissolving gases - gases need to be dissolved before they can diffuse through the alveoli
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Blood structure
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Red blood cells
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Adaptions
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No nucleus, so more room for haemoglobin
Transporting oxygen
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Oxygen enters the lungs when you breathe in, then red blood cells transport the oxygen from the lungs to all the cells in the body
Lungs - oxygen diffuses into the blood, oxygen combines with haemoglobin in red blood cells to become oxyhaemoglobin
In body tissues - oxyhaemoglobin spilts up into haemoglobin and oxygen to release oxygen to the cells
White blood cells
Help to defend against microorganisms that cause disease, part of the immune system
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Blood vessels
Arteries
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Heart pumps out blood at high pressure, so artert walls are strong and elastic
They contain thick layers of muscle to make them strong and elastic fibers to allow them to stretch and spring back
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Capillaries
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Walls are 1 cells thick, so low diffusion distance
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