Blood Pressure

Blood Pressure

Blood pressure is a critical physiological parameter that reflects the force exerted by circulating blood on the walls of blood vessels. It is one of the principal vital signs and is essential for maintaining adequate blood flow to the body's organs and tissues.

Physiology

Blood pressure is determined by the cardiac output, the resistance of the blood vessels, and the volume of blood. It is typically measured in millimeters of mercury (mmHg) and is expressed as two numbers: systolic and diastolic pressure.

Systolic Pressure

Systolic pressure is the higher of the two numbers and represents the pressure in the arteries when the heart ventricles contract. It is a crucial indicator of cardiovascular function and is influenced by factors such as heart rate, stroke volume, and arterial compliance.

Diastolic Pressure

Diastolic pressure is the lower number and indicates the pressure in the arteries when the heart is at rest between beats. It reflects the resistance of the peripheral blood vessels and the elasticity of the arterial walls.

Measurement

Blood pressure is commonly measured using a sphygmomanometer and a stethoscope. The cuff of the sphygmomanometer is inflated around the upper arm to constrict the artery, and then slowly deflated while listening for the sounds of blood flow using a stethoscope.

Korotkoff Sounds

The sounds heard during blood pressure measurement are known as Korotkoff sounds. The first sound indicates the systolic pressure, while the disappearance of the sound marks the diastolic pressure.

Normal and Abnormal Blood Pressure

Normal blood pressure is typically around 120/80 mmHg. However, it can vary based on age, sex, and other factors.

Hypertension

Hypertension, or high blood pressure, is a condition where the blood pressure is consistently elevated above normal levels. It is a major risk factor for cardiovascular diseases such as stroke and myocardial infarction.

Hypotension

Hypotension, or low blood pressure, can lead to symptoms such as dizziness and fainting. It may occur due to dehydration, blood loss, or certain medical conditions.

Regulation

Blood pressure is regulated by a complex interplay of neural, hormonal, and renal mechanisms. The autonomic nervous system, the renin-angiotensin-aldosterone system, and the kidneys play significant roles in maintaining blood pressure homeostasis.

Clinical Significance

Monitoring blood pressure is crucial in diagnosing and managing various medical conditions. It is a key component of routine health assessments and is used to evaluate the effectiveness of treatments for hypertension and other cardiovascular disorders.

Also see

• Cardiovascular system
• Hypertension
• Hypotension
• Heart rate
• Stroke volume

Classification
External resources