- Blood pressure is defined as the pressure of the blood against the walls of the main arteries. Pressure is highest during systole when the ventricles of the heart are contracting (systolic pressure), and lowest during the diastole when the ventricles are relaxing and refilling (diastolic pressure).
- Blood pressure is measured in millimeters of mercury at the brachial artery in the arm where the blood pressure is most similar to that of blood leaving the heart.
- The normal range of blood pressure varies with age. A young adult would be expected have a systolic blood pressure of about 120 mm mercury and a diastolic pressure of about 80 mm mercury. This is recorded as 120/80.
- Individual variations are common. Muscular exertion and emotional factors such as fear, excitement and stress all raise systolic pressure. Systolic blood pressure is normally at its lowest during sleep.
- Blood pressure is adjusted to its normal level by the sympathetic nervous system and hormone controls.
- High Blood Pressure or Hypertension is the elevation of arterial blood pressure.
- May be of unknown cause in which case it’s called essential hypertension
- May be the result of kidney disease renal hypertension.
- Hypertension that is the result of endocrine disease or artery disease is called symptomatic or secondary hypertension
Complications of Hypertension
- Heart failure
- Cerebral hemorrhage (stroke)
- Kidney failure
Hypertension is symptom-less until the symptoms of complications develop. Diagnosis and treatment are very important as management of hypertension can prevent the development of complications.
Low Blood Pressure or Hypotension is a condition in which the arterial blood pressure is abnormally low.
- It occurs after excessive fluid loss e.g. through diarrhea or following severe blood loss from any cause.
- Some people experience a temporary fall in blood pressure when rising from a horizontal position (postural hypotension) and this may result in a simple faint episode.