| Blood Pressure & Hypertension Part 1: An Explanation |
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It is natural for blood pressure to fluctuate throughout the day in response to the activities and situations we face – for example, normal daily factors such as stress (or state of relaxation), cigarette smoking, exercise and food all have the ability to affect blood pressure. These fluctuations are managed by a variety of hormonal and nervous system responses that work together to maintain a constant flow of blood through the circulatory system. Blood pressure is measured in millimeters of mercury (mmHg) and is expressed as a fraction. The top reading is called the systolic reading and represents the pressure placed on artery walls when the heart contracts (beats) to eject blood into circulation. The bottom (diastolic) reading represents the pressure that blood pressure places on artery walls when the heart is relaxed (ie 'resting' between beats).
Normal blood pressure is considered to be 120/80 mmHg. Table 1 shows classifications for normal and hypertensive blood pressure results.
Table 1: Blood Pressure Results
HypertensionHypertension is the term used to describe blood pressure that remains elevated over a period of time. In general, hypertension normally involves blood pressure of 140/90 and above (or more specifically, a systolic reading of 140 or greater, and/or a diastolic reading of 90 or greater). Hypertension is unique in the sense that it is classified as a disease, but is also considered a risk factor towards the development of other diseases, particularly cardiovascular disease, eye conditions and kidney dysfunction. Therefore, regular monitoring of blood pressure is recommended for the early detection of hypertension and the early introduction of management strategies to manage, control and potentially reverse the situation. Hypertension is not generally caused by one particular factor, but by a combination of factors occurring simultaneously. Factors that can contribute to the development of hypertension include:
Some factors that contribute to the development of hypertension cannot be altered (like age, family history and ethnic background). In this case, lifestyle modifications can be used to prevent the development of hypertension, decrease the severity of the hypertensive state, and slow the rate at which the hypertensive state becomes worse. These lifestyle modifications can include dietary changes, weight loss and regular exercise. Other factors, like insulin resistance, smoking, high salt and alcohol intake, obesity and low potassium intake can be addressed through lifestyle modification to prevent hypertension or to manage the condition once it has been diagnosed.
TreatmentTreatment of hypertension can involve lifestyle modification (dietary changes and regular exercise) and/or medications. Lifestyle modification is the preferred treatment strategy for people with pre-hypertension. At best, lifestyle modification can reverse the pre-hypertensive state, and at worse, slow the progression of the disease. Medications are generally reserved for the treatment of more advanced cases of hypertension or for cases in which lifestyle modification has not been successful. In more advanced cases of hypertension, multiple medications may be needed to control blood pressure. Unless otherwise specified by a doctor, lifestyle modification will also be used in conjunction with medication use to control blood pressure. Once the hypertensive state has been stabilised by medications, lifestyle modifications can assist in maintaining and preventing further decline of the condition. Whilst medications are available to control hypertension, it is much more preferable to prevent the condition from occurring in the first place. Because hypertension represents a risk towards the development of other serious conditions (such as cardiovascular disease, kidney failure, poor vision or blindness), preventing hypertension and maintaining a normal blood pressure will have a positive effect on total overall health. Secondly, medications work by manipulating the physiological systems of the body – in the case of hypertension, medications cause physiological changes aimed at improving the regulatory functions that control blood pressure. However the physiological systems of the body do not function independently, but rather as a series of intertwined processes. This means that changes in blood pressure control mechanisms bought about by hypertension medication can also alter the functions of other systems of the body. Therefore, although medications can help solve hypertension, they can also present a range of side effects and other risks that will need to be managed to ensure the long-term health of the individual.
Part 2 of this series on blood pressure and hypertension will take a more technical look at blood pressure and how it is controlled. Part 3 will examine how lifestyle modifications like diet and exercise can be effectively used to control blood pressure in the short and long term.
ReferencesPorth, C.M. (2009). Disorders of blood pressure regulation. In C.M. Porth & G. Matfin (Eds). Pathophysiolgy: Concepts of altered health states. US Department of Health and Human Services. (2004). The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) – complete report. |
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Blood pressure is one of the most variable functions of the body, but also one of the most well-regulated. In simple terms, blood pressure represents the amount of force exerted on artery walls as blood circulates around the body and is required to ensure that vital organs receive a steady and constant supply of blood.