Arterioles are smaller vessels that branch off from the arteries and regulate blood pressure. If, for some reason, the arterioles are narrowed, it's harder for the blood to pass through them. When that happens, blood pressure rises and your heart works harder. High blood pressure affects one out of four Americans, with African-Americans being at highest risk. If your parents had high blood pressure you may be at greater risk as well.
Gender is a factor, too, since men are more likely to develop hypertension than women.
Age also plays a part since high blood pressure generally occurs over the age of 35. The older a person gets, the greater the chance of high blood pressure. Obesity, alcohol consumption, the taking of oral contraceptives and sedentary lifestyles may also be factors. Heavy sodium consumption increases blood pressure in some individuals. As a result, people diagnosed with high blood pressure are placed on sodium restricted diets.