Before we talk about HIGH blood pressure and how it affects your body, we should first talk about blood pressure in general.
"Blood pressure" is simply the pressure inside your blood vessels.
When your heart relaxes in between heartbeats, the pressure inside your blood vessels goes down. You need healthy, elastic blood vessels, that stretch and shrink as the pressure goes up and down, in order to push the blood to your vital organs.
As blood vessels travel away from the heart, they branch off and get gradually smaller, just like the branches of a tree. One branch may go to the brain while another may go to your kidneys. As blood is pumped from your heart into your blood vessels, enough pressure is created to send your blood to all other parts of your body.