Expansion
Elastic arteries store energy in systole and release it in diastole
Expansion
The aorta and great arteries are rich in elastin. During systole they distend and store about half the stroke volume as potential energy. During diastole their elastic recoil maintains forward flow and diastolic pressure.
The result is that intermittent ventricular ejection becomes continuous capillary flow, and the ventricle does less work than it would against a rigid tube.
With ageing, elastin is replaced by collagen and the arteries stiffen. Consequences:
- Systolic pressure rises, since the aorta cannot buffer the ejected volume
- Diastolic pressure falls, since recoil is reduced
- Pulse pressure widens, producing isolated systolic hypertension
- Reflected pressure waves return earlier, augmenting late systolic pressure and raising afterload
Because coronary perfusion depends on diastolic pressure, arterial stiffening simultaneously raises myocardial demand and reduces supply.