Blood pressure

Blod pressure is the force that causes the blood to circulate on the walls of blood vessels. As the blood moves through the arteries and veins, it decreases. Blood pressure can be measured by sphygmomanometer, and it uses a coulumn of mecury to reflect the circulating pressure."The average pressure throughout the cardiac cycle is reported as mean blood pressure(arterial pressure); the pulse pressure reflects the difference between the maximum and minimum pressures measured."
"All levels of arterial pressure put mechanical stress on the arterial walls." High blood pressure increases the work of the heart and progresion of unhealthy tissue growth. The higher the pressure, the higher the stress that is presen. Then the heart muscles tend to thicker enlarge and become weak;over time. High blood pressure is also the result of stroke, heart attacks and heart failure. Blood pressure that is too low is known as hypotension. Low blood pressure is a sign of severe disease;the perfusion of the brainbecomes critically decreased, causing lightheadedness, weakness and fainting.



Refrence:http://en.wikipedia.org/wiki/Blood_pressure#High_arterial_pressure