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1 This system is dependent on hormonal changes which induce transcription of genes to produce vasoactive proteins, making it a slower means of controlling blood pressure compared to the baroreceptor reflex. The renin-angiotensin-aldosterone system (RAAS) is an essential component of blood pressure regulation that acts to increase blood volume and increase systemic vascular resistance.

Intermediate and long-term regulation of BP Renin-angiotensin-aldosterone system (RAAS) 2 The net effect of this is increased cardiac contractility, increased heart rate and increased systemic vasoconstriction, causing an overall increase in blood pressure. The net effect of this is a reduction in heart rate and systemic vasodilatation collectively reducing MABP.Ĭonversely, when blood pressure decreases, there is less baroreceptor activation meaning the impulse rate of the afferent fibres decreases, causing the cardiovascular centre to increase SNS outflow and decrease PSNS outflow. In response to this, the parasympathetic nervous system (PSNS) activity increases and the sympathetic nervous system (SNS) activity decreases. 1 Increases in arterial pressure result in increased baroreceptor activity, which then increases the firing rate in the associated afferent neurons, carrying this information to the cardiovascular centre in the medulla. There are mechanoreceptors known as baroreceptors located in the aortic arch and carotid sinus, which constantly monitor the MABP and pulse pressure. This reflex is crucial for the maintenance of blood pressure throughout the day and in its absence, even a slight change in posture could lead to significant changes in blood pressure. The baroreceptor reflex is a neurally-mediated reflex that regulates blood pressure in the short-term. Rapid control of blood pressure Baroreceptor reflex

Pulse pressure is calculated by subtracting DBP from SBP (i.e.

MABP can be calculated from the SBP and DBP using the following formula:

Mean arterial blood pressure = Cardiac output x Systemic vascular resistance.

Mean arterial blood pressure (MABP) is another method of assessing blood pressure: 1

Diastolic blood pressure (DBP) represents the pressure in the blood vessels between heartbeats (diastole).

Systolic blood pressure (SBP) represents the pressure in the blood vessels when the heart contracts (systole).

ruptured blood vessels, reduced perfusion to organs) and therefore the mechanisms which maintain BP homeostasis need to be robust.īlood pressure can be measured in a number of different ways, with the most common being systolic and diastolic blood pressure: Blood pressure which is too high or too low can lead to a wide range of pathology (e.g. BP is controlled by a variety of complex physiological mechanisms which allow both short term adaptation and longer-term maintenance of BP within a normal range.

Blood pressure (BP) can provide insight into the workings of the heart and vessels of the body.