Understanding blood pressure

DOC, what is hypertension? I’m sure every physician is often faced with this question. We also call it high blood pressure.  

Every time I water my plants, which is not very often, I am reminded of a simplistic view of hypertension. In its simplest form, understanding hypertension is a bit like understanding the water that flows through the garden hose. The pressure within the hose will depend on the size of the hose, the material and the amount of water flowing within it.