Capillaries, arteries & veins (Edexcel Int. A-level Biology)

This fully-resourced lesson explores how the structure of capillaries, arteries and veins relate to their functions. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 1.7 of the Edexcel International A-level Biology specification.

This lesson has been written to build on any prior knowledge from iGCSE or earlier in this topic to enable students to fully understand each type of blood vessel has its particular features. Students will be able to make the connection between the narrow lumen and elastic tissue in the walls of arteries and the need to maintain the high pressure of the blood. A quick version of GUESS WHO is used to introduce smooth muscle and collagen as the substances that are found in the tunica media and externa and again the reason for their presence is explored and explained. The next part of the lesson looks at the role of the capillaries in exchange and links are made to diffusion to ensure that students can explain how the red blood cells pressing against the endothelium results in a short diffusion distance. The remainder of the lesson considers the structure of the veins and students are challenged to explain how the differences to those observed in arteries is due to the lower blood pressure found in these vessels. Valves are introduced and important mechanisms like the skeletal muscle pump are discussed to ensure that students can understand how the return of blood to the right atrium of the heart is maintained.