This concise lesson describes the essential features of the alveolar epithelium as a surface over which gas exchange takes place. The engaging PowerPoint has been designed to cover the fourth part of point 3.2 of the AQA A-level Biology specification and also includes an introduction to ventilation which is covered in the following lesson.
Gas exchange at the alveoli is a topic that was covered at GCSE so this lesson has been written to challenge the recall of that knowledge and to build on it.
The main focus of the lesson is the type of epithelium found lining the alveoli and students will discover that a single layer of flattened cells known as simple, squamous epithelium acts to reduce the diffusion distance. Again, students will have met this in a lesson in topic 2 on specialised cells (and tissues) so a number of prior knowledge checks are used alongside current understanding checks.
The following features of the alveolar epithelium are also covered:
- Surface area
- Moist lining
- Production of surfactant
- The maintenance of a steep concentration gradient
As a constant ventilation supply is critical for the maintenance of the steep concentration gradient, the final part of the lesson considers the mechanism of ventilation to prepare the students for the next lesson.
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This bundle contains 7 lessons which are highly detailed and cover the following points in the surface area to volume ratio, gas exchange and digestion and absorption topics of the AQA A-level Biology specification: * The relationship between the size of an organism or structure and its surface area to volume ratio * The development of systems in larger organisms as adaptations that facilitate exchange as this ratio reduces * Adaptations of gas exchange surfaces in single-celled organisms, insects, bony fish and in the leaf of a dicotyledonous plant * The gross structure of the human gas exchange system * The essential features of the alveolar epithelium over which gas exchange takes place * Ventilation and the exchange of gases in the lungs * Digestion in mammals of carbohydrates, proteins and lipids * Mechanisms for the absorption of the products of digestion by cells lining the ileum If you would like to sample the quality of lessons in this bundle, then download the alveolar epithelium and absorption in the ileum lessons as these have been uploaded for free
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This bundle contains 4 lessons which cover the following content that's set out in topic 3.2 (Gas exchange) of the AQA A-level Biology specification: * Adaptations of gas exchange surfaces as shown by the gas exchange in single-celled organisms, insects, bony fish and the leaves of dicotyledonous plants * The gross structure of the human gas exchange system * The essential features of the alveolar epithelium as a surface over which gas exchange takes place * The mechanism of breathing All of the lessons are detailed and have been intricately planned to contain a wide range of tasks that will challenge the students on their understanding of the current topic as well as their recall of knowledge from previously-covered topics. In this way, the students are encouraged to make links between biological processes in different topics so they are prepared for assessment questions which do just that. Lessons covering topics 3.1, 3.3 and 3.4 are also uploaded
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