Control of blood pressure

Systemic BP depends on the CO and the TPR (total peripheral resistance). The baroreceptor reflex has an important role in the short term, moment-to-moment regulation of BP by controlling peripheral resistance, heart rate and contractility of the heart. Baroreceptor firing accommodates and thus the setting of the baroreceptors increases in response to prolonged elevation in BP.
Hypertension is a sustained elevation in BP, with diastolic BP > 90 mmHg and systolic BP > 140 mmHg. Essential hypertension (i.e. hypertension where the primary cause is unknown) accounts for 95% of all cases. In 5% of cases, a primary cause for the hypertension can be established (i.e. secondary hypertension). Examples of conditions, which can cause hypertension, are: chronic renal disease, renovascular disease, aldosteronism and pheochromocytoma. Although hypertension itself is generally asymptomatic, it is vital to control it as it can have devastating effects on many organs and tissues, such as blood vessels, heart, retina and the kidneys.


The kidney regulates body fluid volumes and therefore, determines circulatory volume and cardiac output. In addition, because the kidney has endocrine function, it contributes to the control of the peripheral resistance through the secretion of renin from the juxtaglomerular apparatus (JGA).