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The Alveolar Epithelium. The exchange of oxygen and carbon dioxide occurs between the alveoli and the capillaries in the lungs. Oxygen and carbon dioxide are exchanged in a process of simple diffusion; (passive movement from high to low concentration) The air in the alveoli contains a high concentration of oxygen.
Adaptations of the Alveoli. The lungs are the gas exchange surface in humans and so are adapted to maximise the exchange of gas by diffusion. Inside the lungs there are many rounded alveolar sacs which give a very large surface area to volume ratio. These alveoli are highly specialised structures.
The alveoli are small sacs, surrounded by capillaries, which are adapted for efficient gaseous exchange. Oxygen diffuses from the alveoli to the blood in the capillaries, and Carbon Dioxide diffuses from the capillaries to the alveoli.
11 de feb. de 2021 · In this A level, IB Biology video Hazel talks you through the adaptations of the alveoli including their increased surface area to volume ratio and use of surfactant.
Each alveolus are adapted to make gas exchange as efficient as possible: Large surface area: there are approximately 700 million alveoli in our lungs with a combined surface area of 70 square meters. Good blood supply: lots of capillaries surround each alveolus.
Many exchange surfaces within organisms have adaptations that increase their surface area. A larger surface area provides more space over which the exchange of substances with the environment can occur. Root hair cells are specialised cells found in the roots of plants.
Alveoli have features that speed up the rate of diffusion so that gases can be exchanged quicly. They have a thin exchange surface - the alevolar epithelium is only one cell thick, which means there's a short diffusion pathway, which speeds up diffusion.
