Carrying blood at high pressure
Arteries carry blood away from the heart. Blood entering them has been forced out by ventricular contraction, so arteries must withstand relatively high pressure.
| Structural feature | Functional significance |
|---|---|
| Thick wall containing smooth muscle and elastic fibres | Provides strength so the artery can tolerate the high pressure generated by the heart. |
| Elastic fibres | Allow the wall to stretch as blood enters, then recoil as the heart relaxes, helping maintain blood pressure. |
| Narrow lumen | Helps maintain the high pressure of the blood. |
| Folded endothelial lining | Allows the inner lining to stretch when blood flow increases. |
The smooth muscle and elastic tissue form a substantial vessel wall around a relatively small lumen. This combination is suited to the pressure produced by repeated contractions of the heart.
Elastic recoil is particularly important between heartbeats because it helps maintain blood pressure as the ventricles relax.
Exam Tip: In a structure–function question, make the link explicit: thick elastic wall → withstands high pressure and recoils → helps maintain pressure between heartbeats.