# Blood Pressure | Factors Maintaining Blood Pressure

What is Blood Pressure?
When your heart beats, it pumps blood around your body to give it the oxygen and energy it needs. It pushes against the sides of the blood vessels as the blood moves. The strength of this pushing is termed as your blood pressure. It puts extra strain on your arteries (and your heart) if your blood pressure is too high. Remember, this may lead to strokes and heart attacks.  There are some key factors that affect blood pressure.
 Fig: Blood pressure measurement process
Factors Controlling Blood Pressure:
There are some key factors which control or maintain blood pressure, those are listed in the below:

Central Factors:
It includes-
• Cardiac output,
• Heart rate.
Peripheral Factors:
It includes-
• Peripheral resistance,
• Blood volume,
• Venous return,
• The elasticity of blood vessels,
• The viscosity of blood flow,
• The diameter of blood vessels,
• The viscosity of blood.
All the above factors have discussed in the following:

1. Cardiac Output:
Systolic pressure is directly proportional to cardiac output. This means when cardiac output increases, the systolic blood pressure is increased and when cardiac output is less, the systolic blood pressure is reduced.

2. Heart Rate:
Marked alteration in the heart rate affects the blood pressure by altering the cardiac output.

3. Peripheral Resistance:
Diastolic pressure is directly proportional to peripheral resistance. This means, when peripheral resistance increases, diastolic pressure increases and when peripheral resistance decreases diastolic pressure decreases.

4. Blood Volume:
Blood pressure is directly proportional to blood volume. If the blood volume increases, there is an increase in venous and cardiac output, resulting in elevation of blood pressure.

5. Venous Return:
Blood pressure is directly proportional to venous return. When venous return increases, there is an increase in ventricular filling and cardiac output, resulting in an elevation of arterial blood pressure.

6. The elasticity of Blood Vessels:

Blood pressure is inversely proportional to the elasticity of blood vessels. This means when the elasticity of blood vessels is reduced (as in atherosclerosis) blood pressure increases.

7. The velocity of Blood Flow:
Blood pressure is directly proportional to the velocity of blood flow within blood vessels. If the velocity of blood flow increases, the resistance is increased. So, blood pressure is increased.

8. The diameter of Blood Pressure:
Blood pressure is inversely proportional to the diameter of the blood vessel. If the diameter decreases, the peripheral resistance increases, leading to an increase in blood pressure.

9. The viscosity of Blood:
Blood pressure is directly proportional to the viscosity of blood. When the viscosity of blood increases, the functional resistance is increased and this increases blood pressure.