Key Area 5
(b) Structure and function of arteries, capillaries and veins
During your N5 biology lessons, you will have learned about arteries, capillaries and veins. In this section, you will expand this knowledge to learn more about their structure and the functional implications of this.
Something to Read...
Open the document below and read the mandatory course notes provided by SQA for this Key Area. You may wish to use your home learning time to copy these notes into a jotter or choose a digital presentation format that suits your learning style.
Something to Watch...
Something to look at...
The diagram to the right highlights some of the key differences in the different blood vessels, most of which you should remember from National 5 Biology.
Veins have an outer layer of connective tissue containing elastic fibres but a much thinner muscular wall than arteries. They contain valves to prevent the backflow of blood.
Capillaries allow exchange of substrates with tissues through their thin walls.
This diagram highlights the structural differences between an artery and a vein. The endothelium lining the central lumen of blood vessels is surrounded by layers of tissue.
In arteries, there is an outer layer of connective tissue containing elastic fibres and a middle layer containing smooth muscle with more elastic fibres. These elastic fibres allow for stretch and recoil as blood surges following heart contractions.
Controlling blood flow
To control blood flow, the smooth muscle surrounding arteries can:
contract causing vasoconstriction
relax causing vasodilation.
You are now ready for your in-class lesson on blood vessels.
You are now ready to move onto Key Area 5c: Exchange of materials.
