A-level Biology Notes

Structure of arteries and arterioles?

- narrow lumen = maintains pressure

- lining made of squamous epithelial cells = smooth lining to reduce friction

- thick walls = withstand pressure

- elastic tissue in wall, 

ventricles contract- elastic tissue stretches to withstand pressure, 

ventricles relax- elastic tissue recoils to maintain pressure and smooth out flow.

- smooth muscles in wall [particularly in arterials],

 smooth muscle contracts- lumen narrows and arteriole constrict, 

smooth muscle relaxes- lumen widens and arteriole dilates

- collagen in wool prevents artery from tearing