Understanding:
• Arteries convey blood at high pressure from the ventricles to the tissues of the body
• Arteries have muscle cells and elastic fibres in their walls
Structure and Function
The function of arteries is to convey blood at high pressure from the heart ventricles to the tissues of the body and lungs
To this end, arteries have a specialised structure in order to accomplish this task:
- They have a narrow lumen (relative to wall thickness) to maintain a high blood pressure (~ 80 – 120 mmHg)
- They have a thick wall containing an outer layer of collagen to prevent the artery from rupturing under the high pressure
- The arterial wall also contains an inner layer of muscle and elastic fibres to help maintain pulse flow (it can contract and stretch)
Structure of a Typical Artery
Understanding:
• The muscle and elastic fibres assist in maintaining blood pressure between pump cycles
Flow of Blood
Blood is expelled from the heart upon ventricular contraction and flows through the arteries in repeated surges called pulses
- This blood flows at a high pressure and the muscle and elastic fibres assist in maintaining this pressure between pumps
The muscle fibres help to form a rigid arterial wall that is capable of withstanding the high blood pressure without rupturing
- Muscle fibres can also contract to narrow the lumen, which increases the pressure between pumps and helps to maintain blood pressure throughout the cardiac cycle
The elastic fibres allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen
- The pressure exerted on the arterial wall is returned to the blood when the artery returns to its normal size (elastic recoil)
- The elastic recoil helps to push the blood forward through the artery as well as maintain arterial pressure between pump cycles
Arterial Blood Flow
