Blood Pressure

Blood pressure is the force exerted by circulating blood on the walls of blood vessels. It constitutes one of the critically important signs of life or vital signs which include heart rate, breathing, and temperature. Blood pressure is generated by the heart pumping blood into the arteries modified by the response of the arteries to the flow of blood.

An individual's blood pressure is expressed as systolic/diastolic blood pressure, for example, 120/80. The systolic blood pressure (the top number) represents the pressure in the arteries as the muscle of the heart contracts and pumps blood into them. The diastolic blood pressure (the bottom number) represents the pressure in the arteries as the muscle of the heart relaxes following its contraction. Blood pressure always is higher when the heart is pumping (squeezing) than when it is relaxing.

• Low blood pressure, also called hypotension, is blood pressure low enough that the flow of blood to the organs of the body is inadequate and symptoms and/or signs of low blood flow develop shock.
• Low pressure alone, without symptoms or signs, usually is not unhealthy.
• The symptoms of low blood pressure include lightheadedness, dizziness, and fainting. These symptoms are most prominent when individuals go from the lying or sitting position to the standing position (orthostatic hypotension). 
• Low blood pressure that causes an inadequate flow of blood to the body's organs can cause strokes, heart attacks, and kidney failure. It's most severe form is shock.
• Common causes of low blood pressure include a reduced volume of blood, heart disease, and medications.
• The cause of low blood pressure can be determined with blood tests, radiologic studies, and cardiac testing to look for heart failure and arrhythmias. 
• Treatment of low blood pressure is determined by the cause of the low pressure.
• Low blood pressure, also called hypotension, is blood pressure low enough that the flow of blood to the organs of the body is inadequate and symptoms and/or signs of low blood flow develop shock.
• Low pressure alone, without symptoms or signs, usually is not unhealthy.
• The symptoms of low blood pressure include lightheadedness, dizziness, and fainting. These symptoms are most prominent when individuals go from the lying or sitting position to the standing position (orthostatic hypotension). 
• Low blood pressure that causes an inadequate flow of blood to the body's organs can cause strokes, heart attacks, and kidney failure. It's most severe form is shock.
• Common causes of low blood pressure include a reduced volume of blood, heart disease, and medications.
• The cause of low blood pressure can be determined with blood tests, radiologic studies, and cardiac testing to look for heart failure and arrhythmias. 
• Treatment of low blood pressure is determined by the cause of the low pressure.

Source: medicinenet.com