Ambulatory blood pressure monitoring: analyzing the normal physiological fluctuations of blood pressure

Blood pressure is not constant throughout a person's life, and the blood pressure of the same person will not be exactly the same on different days or at different times of the same day. Such fluctuations and differences in blood pressure are a normal physiological phenomenon, as long as they are within the normal range. (1) Age: Blood pressure increases with age in children and adolescents, with systolic blood pressure increasing more significantly. After age 40 for men and after age 35 for women, arterial blood pressure increases more significantly, with systolic blood pressure increasing more prominently than diastolic blood pressure. Men's blood pressure is slightly higher than women's, but women experience a more significant increase after menopause. (2) Day and night: Blood pressure is generally higher during the day; it drops to its lowest level during sleep at night. Blood pressure begins to rise after waking up, reaching its highest point between 8:00 and 10:00 am, and then gradually decreases; about 1 hour after lunch, blood pressure begins to rise again, with a small peak between 6:00 and 8:00 pm, but slightly lower than in the morning, and then gradually decreases again. It can be seen that human blood pressure has two peak periods and two troughs during the day, with the difference between the highest and lowest blood pressure reaching 40 mmHg. (3) Season: Generally, blood pressure tends to rise in winter and slightly decrease in summer. However, if it is too hot and the body sweats a lot, the loss of body water increases the viscosity of the blood and the pressure on the blood vessels will also increase accordingly. These factors will cause blood pressure to rise slightly. (4) Body position: Generally, blood pressure is higher when sitting than when standing. In addition, the blood pressure of the four limbs of a normal person may not be exactly the same. The blood pressure of the right upper limb is about 10 mmHg higher than that of the left upper limb. Also, because the femoral artery of the lower limb is thicker and has a larger blood flow, the blood pressure of the lower limb is 20-40 mmHg higher than that of the upper limb when lying flat under normal circumstances, while there is no difference between the blood pressure of the left and right lower limbs. Due to this difference in blood pressure between the left and right upper limbs, it is stipulated that the blood pressure of the right upper limb is used as the standard when measuring blood pressure. (5) Other: Physical activity, mental stress, anger, excitement, insomnia, anxiety, tension, fullness of food or straining during defecation can all cause blood pressure to rise temporarily. The degree of blood pressure rise caused by these conditions is 10-30 mmHg or greater. For healthy individuals, there are no noticeable symptoms, and recovery is usually achieved with rest. However, for those with hypertension, these conditions can easily lead to acute cardiovascular and cerebrovascular events. In my country, the resting systolic blood pressure of healthy young adults is typically 100-120 mmHg, diastolic blood pressure is 60-80 mmHg, and pulse pressure is 30-40 mmHg. Individuals within these ranges generally do not develop hypertension by modifying their lifestyle (quitting smoking, limiting alcohol and high-fat, high-sugar foods, maintaining a regular lifestyle, and increasing exercise). Therefore, hypertension is preventable. Millimeters of mercury (mmHg) is the commonly used unit for blood pressure, while kilopascals (kPa) are used internationally. The conversion is 1 mmHg = 0.133 kPa. Lipids are divided into two main categories: true lipids and lipid phospholipids. True lipids, also known as triglycerides, are the main component of lipids. Lipid phospholipids have a similar structure to fats and mainly consist of phospholipids and steroids. (1) Triglycerides: Triglycerides are the most abundant lipids in the human body, with over 98% stored in adipose tissue, mainly distributed in the subcutaneous tissue, around internal organs, and in the greater omentum and mesentery. The main physiological functions of triglycerides are as follows: ① Energy source for the body: Fat is the most efficient heat-producing substance in the body and is considered a "concentrated energy source" in the diet. All human activities are powered by heat energy and consume calories. 1g of fat can provide 37.6kJ of energy through oxidation in the body, equivalent to 2.25 times that of protein or glucose. ② Supply of essential fatty acids: Essential fatty acids have important physiological functions, promoting development and maintaining the health of the skin and capillaries. They cannot be synthesized in the body and must be obtained from food; hence, they are called essential fatty acids. ③ Insulation: Fat is a poor conductor of heat, thus hindering the loss of body surface temperature and helping to keep warm. Furthermore, it stays in the stomach for a longer time, so eating foods high in fat makes one less likely to feel hungry. ④ Protection: The human body's adipose tissue is distributed under the skin and around the internal organs, acting like a cushion to protect the internal organs and muscles when the body is subjected to mechanical impact from external objects.