There are two major types of hypertension and four more not so common types.
In this case the systolic blood pressure, (the top number), is consistently above 160 mm Hg, and the diastolic below 90 mm Hg. This may occur in older people, and results from the age-related stiffening of the arteries. The loss of elasticity in arteries, like the aorta, is mostly due to arteriosclerosis. The Western lifestyle and diet is believed to be the root cause.