Blood pressure

Your heart pumps blood through your body.

This blood pushes against the walls of your tubes. This push is called blood pressure.

Doctors check this push to see if you are well. They look at two numbers. One number is for the big push. The other is for the small push.

Your pressure can change. It changes when you move or feel stress. It can even change with the weather.

If the push is too high, it is called hypertension. If it is too low, it is called hypotension. Keeping it normal helps your heart stay strong.

Your heart pumps blood through your body. This blood pushes against the walls of your tubes. We call these tubes blood vessels.

This push is called blood pressure.

Doctors check this push to see if you are well. They look at two numbers. The first is systolic pressure. This is the big push during a heartbeat. The second is diastolic pressure. This is the small push between heartbeats.

Your pressure changes often. It can change if you move or feel stress. It can even change with the weather. Some people use a tool called a sphygmomanometer. This tool helps measure the push.

If the push is too high, it is called hypertension. This can be a risk for many diseases. It can hurt your heart or kidneys. If the push is too low, it is called hypotension. Keeping your pressure in a normal range helps you stay healthy.

Blood pressure is the force of your blood pushing against the walls of your blood vessels. Most of this force comes from your heart pumping blood through your whole body.

Doctors call this one of the vital signs to check your health. They look at it alongside your heart rate and body temperature. It is very important to know if your pressure is in a healthy range. A normal resting pressure for an adult is about 120/80 mmHg.

When doctors measure this, they look at two main numbers. The first number is called systolic pressure. This is the maximum pressure when your heart beats. The second number is called diastolic pressure. This is the minimum pressure between your heartbeats.

The difference between these two numbers is called pulse pressure. The average pressure during a whole heartbeat is called mean arterial pressure. You can measure this using a tool called a sphygmomanometer.

In the past, healthcare workers used a method called auscultation. This means they used a stethoscope to listen to your arm artery. They would use a sphygmomanometer to squeeze the artery. This is still considered a gold standard for measuring pressure in clinics. Today, many people use semi-automated tools instead. These tools are easier to use and do not use mercury. This is helpful because mercury can be toxic to people and the earth.

Your blood pressure changes all the time. It can change based on your activity or how you feel. It even changes with the temperature or the noise around you.

Your pressure is usually highest in the morning and evening. It is usually lowest while you are sleeping at night. If your pressure is consistently too high, it is called hypertension. If it is too low, it is called hypotension. Long-term hypertension can lead to serious problems like heart disease or kidney failure.

Blood pressure is different for everyone based on age and size. For example, babies have much lower pressure than adults. A full-term infant might have a systolic pressure between 65 and 95 mmHg. As people get older, their systolic pressure often rises. This can happen because the arteries become more stiff.

Even in a baby, the heart works hard to drive blood through the body. Understanding these numbers helps doctors keep everyone healthy and strong.

Blood pressure refers to the force of circulating blood against the walls of blood vessels.

This pressure is primarily created by the heart pumping blood through the circulatory system. In medical settings, the term usually describes the pressure found in a brachial artery. Healthcare professionals consider blood pressure one of the vital signs. They evaluate it alongside respiratory rate, heart rate, oxygen saturation, and body temperature. Understanding these measurements is essential for assessing a person's overall health status.

To understand the mechanism, one must look at the cardiac cycle. This cycle consists of two distinct phases: systole and diastole.

Systolic pressure is the maximum pressure reached during a single heartbeat. Diastolic pressure is the minimum pressure recorded between heartbeats. When doctors record blood pressure, they express it as systolic over diastolic. For example, a normal resting pressure for an adult is approximately 120/80 mmHg. The difference between these two values is called pulse pressure. The average pressure during the entire cycle is the mean arterial pressure.

Blood pressure is not a static number; it is influenced by several biological factors. These include cardiac output, systemic vascular resistance, blood volume, and arterial stiffness.

The body uses baroreceptors to regulate pressure in the short term. These sensors send signals to the brain. The brain then influences the nervous and endocrine systems to adjust pressure. Over longer periods, pressure can vary based on age, sex, and even posture. It also follows a circadian rhythm, meaning it fluctuates over a 24-hour period. Readings are typically highest in the early morning and evening. They are usually lowest during the night.

Clinicians use different classifications to determine if blood pressure is healthy. A person with normal pressure is described as having normotension. If pressure is consistently too low, the condition is called hypotension. If pressure is consistently too high, it is called hypertension.

Guidelines for these categories change depending on the setting. There are different thresholds for office readings, home measurements, and 24-hour ambulatory monitoring. For instance, the American College of Cardiology uses different numbers for home use than for a clinic. For example, stage 1 hypertension in an office is 130–139 mmHg systolic. However, for 24-hour ambulatory monitoring, the threshold is 125–129 mmHg.

Historically, the standard method for measuring pressure was auscultation. This involves using a stethoscope to listen to sounds in an arm artery. A device called a sphygmomanometer is used to compress the artery during this process.

While auscultation is still a gold standard, semi-automated methods are now very common. These newer tools are often used for home monitoring. They are preferred because they are easy to use and avoid the use of mercury. This shift occurred due to concerns regarding mercury toxicity and the cost of traditional equipment.

Blood pressure levels vary significantly across different stages of life. For example, fetal blood pressure is driven by the fetal heart rather than the mother's. At 20 weeks of gestation, fetal aortic pressure is about 30 mmHg. By 40 weeks, it increases to approximately 45 mmHg. Full-term infants have a systolic range of 65–95 mmHg. In children, normal ranges depend on their height, age, and sex. As adults age, systolic pressure tends to rise, often up to age 70. This rise is frequently attributed to increased stiffness in the arteries. This can lead to isolated systolic hypertension in older populations.

Maintaining healthy blood pressure is critical because high pressure causes mechanical stress.

This stress can damage arterial walls and increase the heart's workload. Over time, it can cause unhealthy tissue growth called atheroma. Persistent hypertension is a major risk factor for stroke, heart disease, and kidney failure. Even moderate elevations can shorten a person's life expectancy. In extreme cases, such as a hypertensive emergency where pressure exceeds 180/120 mmHg, the risks are very high. Monitoring these levels helps prevent these serious cardiovascular events.