Causes & Physiology of Hypertension

When the heart pumps blood, the blood exerts pressure against the blood vessel walls. Hypertension, or high blood pressure, occurs when this pressure is higher than normal. According to the American Heart Association, hypertension affects about 73 million Americans.

Physiological Effects

• Blood pressure depends on heart output, blood vessel resistance, volume of blood, and blood distribution to organs. Secondary factors include the activities of the nervous system and certain hormones.

Symptoms

• Because it often causes no symptoms, hypertension is known as the "silent killer." In the advanced stages, however, headaches, sweating, rapid pulse, dizziness, shortness of breath and visual disturbances may occur.

Types

• Primary hypertension is not caused by an underlying disease. Risk factors include smoking, stress, being overweight, excessive stimulant use, and high sodium intake. Secondary hypertension is caused by an underlying health problem, such as arteriosclerosis, adrenal disorders or poor kidney function.

Measurements

• Blood pressure is represented by a pair of numbers: systolic pressure (pressure exerted when the heart beats) and diastolic pressure (pressure exerted when the heart is at rest.)

Treatment

• Doctors commonly prescribe drugs to reduce high blood pressure, and may recommend a low-sodium diet, reducing stress, and (if applicable) quitting smoking.