>>12313887Blood pressure is what ages our arteries and makes them stiff when they should be flexible. The higher your blood pressure, the faster your arteries harden. The next logical question is, why is it a problem if your arteries are stiff? There are 2 broad reasons:
1. Elastic arteries dampen the pulsatile flow of the heart: during systole your heart pumps hard and your arteries expand to collect that blood, and during diastole your arteries relax, which maintains the flow through your organs.
i. The microcirculation needs blood all the time (since it needs oxygen all the time), if you don't dampen the pulsatile flow, then every time your heart enters diastole, your microcirculation will be hypoxic. This can worsen the function of your organs over time.
ii. The microcirculation is fragile, if you don't dampen the high systolic blood pressure pumped from the heart, you may damage the microcirculation. Over time the arterioles and microcirculation adapt by becoming "sclerotic" and fibrotic, which in the end causes all other sorts of things (atherosclerosis, arteriolosclerosis; both of which can cause stroke, heart attacks, kidney disease, etc.).
2. Elastic arteries decrease the load your heart has to pump against. Imagine if you were pumping blood through steel tubes, this would be harder than filling up a balloon.
i. Long term increases in blood pressure can increase the load of the heart causing concentric hypertrophy. This concentric hypertrophy results in greater myocardial oxygen demand and sometimes the excess heart muscle can diminish the filling capacity of the heart causing decrease in cardiac output (and hence myocardial oxygen supply), so, it is a double whammy on your heart.
These are the reasons why high blood pressure ages you faster. and hence why it is called the "silent killer". "Hypertension" is only a simplistic or summary of basically saying "higher blood pressure than you need".
