10.2.6 Regulation of Blood Pressure

1. Pressure is how much force exerted on one unit area of a surface.
2. Blood pressure is the pressure exerted by the blood on the walls of the blood vessels.
3. Sometime, it is also called the arterial blood pressure as it is the pressure in the arteries.

Normal Blood Pressure

1. When measuring blood pressure, we measure the
1. systolic pressure (highest pressure measured in the aorta and the arteries during ventricular contraction)
2. diastolic pressure (lowest pressure measured after the contraction of the heart while the chambers of the heart refill with blood.)
2. For an adult, the normal systolic pressure is 120 mm Hg whereas the diastolic pressure is 80 mm Hg.
3. However, blood pressure may varies throughout the day.

Factors Affecting Blood Pressure

1. Blood pressure can be affected by the following factors:
1. Rate of heart beat
   Higher heart rate, higher blood pressure.
2. Volume of blood in the body
   Bigger volume, higher blood pressure.
3. Rate and volume of blood flow
   Higher rate and volume of blood flow, higher rate of heart pumping, higher blood pressure.
4. Resistance of blood vessels
   Higher resistance (smaller blood vessels, rough blood vessel wall), higher blood pressure. 

Regulation of Blood Pressure