Could a doctor please explain to me how is renal related to hypertension?

Kidneys: kidneys give out a hormone that controls blood pressure. meds block that chemical. some water pills reduce blood pressure by letting fluids pass thru kidneys. sometimes blood flow is blocked to kidney circulation and BP rises.

Mechanisms: Excessive high blood pressure will damage the kidneys over time. Poor blood flow through the kidneys (as in renal artery stenosis) will cause the kidneys to increase BP through secretion of hormones, in order to maintain adequate flow.

Ok, here goes....: The kidney is known to be involved with blood pressure (BP) regulation through a hormone system in the body called the renin-angiotensin system. The kidney senses the BP coming through and releases more of these hormones if it detects a lowering in the BP. These hormones clamp down on blood vessels in the body there by raising the BP. Certain BP meds work to block this system thereby lowering BP.