Hypertension: An introduction

Hello. My name’s Dr Alister McNeish from Reading School of Pharmacy. And today I’m going to talk about hypertension, or high blood pressure. And the reason that this is such an important topic is that high blood pressure is the largest risk factor for the development of cardiovascular disease. It affects around about 25% of the adult population in the UK, and its incidence increases with age such that about 50% of the population will suffer from hypertension over the age of 60. So how can we describe high blood pressure? Well, you could imagine your cardiovascular system like a central heating system, with the heart as the pump, and the blood vessels, particularly the arteries, as the pipes.

Now, the blood flowing through this system exerts pressure on the pump and the pipes. And you can imagine if the pump works harder, the pressure will build up in the system. Similarly, if the pipes get narrower, the pressure will build up. And this is exactly what happens when we begin to age. Our arteries begin to narrow and begin to fuzz up with atherosclerotic plaques. And that increases resistance to the blood flow and makes our hearts work harder. And that leads to development of heart damage and the development of high blood pressure. So as the blood pressure increases, that leads to extra strain on the heart. That can lead to heart damage.

And the increase in blood pressure can also lead to rupturing of atherosclerotic plaques. And that in turn will cause thrombotic events. So the body can regulate blood pressure by altering the heart rate, by altering arterial diameter to decrease the resistance, and also to reduce the blood volume. There are specialised cells in the walls of the blood vessel in the aortic arch called the carotid body. Now, the carotid body senses changes in blood pressure, sends nervous impulses to the brain. The brain then sends nervous impulses to the heart, telling the heart to slow down and telling the blood vessels to relax.

Therefore, that will decrease the amount of work the heart has to do and decrease the resistance to blood flow, therefore reducing blood pressure.