# What is pressure?

If you feel a headache, as if something is squeezing your head, or, conversely, tearing it from the inside, then, most likely, you have problems with blood pressure. What is pressure? What is it like? Now consider this question.

Pressure is a physical quantity that characterizes the force acting on an object. The pressure value depends on the force of action (F) and the area of ​​interaction (S).

## Pressure of the outside world

Maybe you didn’t think about it, but a huge layer of air presses on us all the time. This is atmospheric pressure. It affects all bodies on Earth. There are no exceptions.

The higher you go uphill, the lower will be the value of atmospheric pressure, measured in Pascals or millimeters of mercury.

Imagine the force with which the air presses on us, it is difficult. This is a very big power. So why do we feel completely normal in such conditions? And this happens for two reasons: firstly, the pressure of the air column acts on us evenly from all sides, and secondly, there is pressure inside us that is opposite to the atmospheric pressure along the vector.

## Pressure inside us

Blood flows through our veins, which is set in motion by contractions of the heart. The pressure that blood exerts at the time of contraction is called arterial. It is also measured in millimeters of mercury.

Blood pressure has two indicators: systolic pressure (upper, first number) and diastolic (lower, second number). To calculate the systolic pressure, use the formula: 109 + (0.5 × age) + (0.1 × weight). There is another formula for determining diastolic pressure: 63 + (0.1 × age) + (0.15 × weight). The two numbers received are your normal pressure.

To learn how to measure blood pressure in the human body at the moment, read this article.

Over the course of evolution, living beings with blood adapted to the pressure of air masses. Thus, the arterial pressure (BP) in theory is equal to atmospheric - 1 kgf / cm2. However, there are moments when the heart is working in an extreme mode, which leads to pressure surges.

At any given time, you experience pressure from the outside and inside. Atmospheric pressure (external pressure) is the force with which air masses affect your body area.The higher you are above sea level, the lower is atmospheric pressure. The normal figure is 760 millimeters of mercury.

Simultaneously with the pressure of the external you are experiencing and internal. If we are talking about the pressure of blood on the walls of blood vessels, then this is blood pressure. It is also measured in millimeters of mercury, but consists of two parameters: the pressure of the upper (inside the arteries) and the pressure of the lower (inside the veins). It is very important to monitor this indicator at the age of 12 to 19 years old (active growth) and from 45 years old (aging).

If you experience frequent headaches, then contact your local health center. Perhaps something is wrong with your heart.