Blood pressure: A barometer of life – Exploring the dynamics of blood circulation and the definition of normal values

Fluctuating Blood Pressure: Blood pressure reflects a person's health status and is a barometer of whether life activities are normal. Both excessively low and high blood pressure can have serious effects on the body. If you frequently experience palpitations, fatigue, dizziness, or other symptoms, you should be careful.

By carefully reading this article, you will gain comprehensive and systematic theoretical knowledge. In addition, numerous case studies and anecdotes will not only bring you interest but also provide an accessible analysis of blood pressure, a crucial indicator of health. Blood Pressure is a Vital Indicator: For life to survive, it must maintain its own orderly state, and a key indicator of this orderly state is blood pressure. We say that blood pressure is the lateral pressure exerted by blood on the walls of blood vessels per unit area. Blood pressure requires two factors: first, the cardiovascular system must be filled with blood; the other important factor is the heart's pumping of blood. Under normal circumstances, the amount of blood in the body remains relatively constant. For example, a man weighing 70 kg has a total blood volume of approximately 5.5 L. In other words, a normal adult male has an average of 75-80 ml of blood per kilogram of body weight, while a normal adult female has about 70 ml of blood per kilogram of body weight. If a person loses a small amount of blood at once, not exceeding 10% of their total blood volume, it will not cause significant cardiovascular dysfunction or discomfort.

If a person loses a large amount of blood at once, reaching 20% ​​of their total blood volume, the cardiovascular system will be affected, leading to dizziness, paleness, weakness, and many other discomforts. If a person loses a large amount of blood at once, reaching or exceeding 30% of their total blood volume, it will be life-threatening. At this time, blood pressure is often below 50 mmHg or even lower. Knowing the relevant values ​​for total blood volume and blood loss, let's learn about the heart's ejection of blood. The heart is a hollow organ composed of cardiac muscle tissue and has valves. It is the driving force of blood circulation. During life, the heart constantly performs alternating contractions (arterial blood ejection) and relaxations (venous blood return), working like a "pump," circulating blood in a single direction, generating blood pressure, and sustaining life. The amount of blood ejected with each heartbeat varies depending on gender, age, and other physiological conditions. In a healthy adult male at rest, the average heart rate is 75 beats per minute, and the cardiac output is 5 liters per minute, which can reach 25-35 liters per minute during strenuous exercise. These figures show that exercise can increase the amount of blood ejected from the heart, thus promoting health. Note: Blood flows in blood vessels; the heart's pumping power and the resistance of the blood vessels create blood pressure. Blood pressure reflects a person's health status, which is why medicine considers it one of the most important indicators of life. What should normal blood pressure be? In the midst of a stressful life and work, people often experience transient dizziness, headaches, and some even feel palpitations and fatigue. These symptoms are often related to blood pressure. Both higher and lower than normal blood pressure can cause these symptoms. What should normal blood pressure be? This is a topic of concern. First, it's important to know the unit of measurement for blood pressure. Blood pressure is usually measured in millimeters of mercury (mmHg), but now it's transitioned to kilopascals (kPa). 1 mmHg = 0.133 kPa. When reading blood pressure, read the systolic pressure first, then the diastolic pressure. For example, when blood pressure is 120/80 mmHg, it should be read as 120 first, then 80. People often read it backwards, 80, 120—this is incorrect. Blood pressure classification (mmHg) for adults over 18 years of age at rest: Low blood pressure: Systolic pressure <90, Diastolic pressure <60; Normal blood pressure: Systolic pressure <130, Diastolic pressure <85; Borderline blood pressure: Systolic pressure 128–146, Diastolic pressure 84–89; Mild hypertension: Systolic pressure 147–159, Diastolic pressure 90–104; Moderate hypertension: Systolic pressure 160–180, Diastolic pressure 105–114; Severe hypertension: Systolic pressure above 180, Diastolic pressure above 114. Blood pressure in healthy individuals at rest is relatively stable, but there are individual differences, as well as differences based on gender and age. Generally speaking, obese people have slightly higher blood pressure than people of average build.