Final answer:
Arterial blood pressure is expressed in millimeters of mercury (mmHg), with a normal reading being around 120/80 mmHg, which represents systolic and diastolic pressures during the cardiac cycle. Blood pressure higher than 130/80 mmHg is considered hypertension.
Step-by-step explanation:
Arterial blood pressure is typically measured in millimeters of mercury (mmHg), and a normal value is often considered to be around 120/80 mmHg. This measurement is expressed as a ratio of two numbers: the systolic pressure, which is the higher value when the heart contracts to pump blood, and the diastolic pressure, which is the lower value when the heart relaxes between beats. The standard for normal blood pressure is derived from the need to represent the peak arterial pressure resulting from the heart's contraction and the trough pressure during the heart's resting phase between contractions.
Hypertension and hypotension are conditions related to abnormal blood pressure readings. Hypertension is chronically elevated blood pressure, and current guidelines list this as 130/80 mmHg or higher. Hypotension, on the other hand, refers to blood pressure that is too low and can have various causes, including dehydration or severe blood loss.