(p. 743) Physical factors in arterial ageing 

Arterial structure and function change progressively with advancing age. Owing to long-lasting repetitive stretch with intermittent cardiac contraction, elastic fibres in the tunica media of large arteries progressively degenerate and are replaced by collagenous fibres. Such degeneration causes elastic arteries to stiffen and dilate. Stiffening of the large arteries not only increases amplitude of the incident pressure wave but also hastens the return of the reflected pressure wave, thereby widening the pulse pressure in the central aorta. This widening increases the cardiac afterload during systole, while it decreases coronary flow during diastole, thus predisposing to heart failure and coronary ischaemia. Also, the excessive pulsatile pressure is transmitted deeply into the renal and cerebral microvasculature causing microalbuminuria and lacunar infarction. Although arterial ageing is considered an inevitable and irreversible process, it can be delayed through optimal blood pressure control.