High blood pressure mainly affects

High blood pressure leads to heart diseases and also affects vital organs like brain and kidney. 

High blood pressure may cause a weakened blood vessel to burst inside the brain, causing bleeding on and into surrounding tissues. This is called a haemorrhagic stroke.High blood pressure can also cause blood clots to form in the arteries of the brain, blocking blood flow and potentially causing an ischemic stroke. 

High blood pressure can constrict and narrow the blood vessels, which eventually damages and weakens them throughout the body, including in the kidneys. The narrowing reduces blood flow. When this happens, the kidneys are not able to remove all wastes and extra fluid from the body. Extra fluid in the blood vessels can raise your blood pressure even more, creating a dangerous cycle, and cause more damage leading to kidney failure.