Figure 45.1 Blood pressure control mechanisms This figure shows the interplay between the nervous system, the endocrine system, vasoactive substances and the kidneys in the control of blood pressure. The nervous system influences cardiac output and blood vessel diameter. The release of adrenaline and noradrenaline from the adrenal gland alto influences these parameters, as well as stimulating the release of renin into the blood from renal arterioles. Renin release leads to the production of anglotensin E, a potent vasoconstrictor, which in turn causes the secretion of aldosteronism the adrenal cortex. Aldosteronismes sodium and water retention, which increases blood volume and leads to an elevation in blood pressure. Indeed, renin release is triggered whenever renal blood flow is compromised. Antidiuretic hormone from the pituitary also leads to an increase in blood volume through water retention. Vasoactive substances, such as nitric oxide, prostaglandins and endothelin-1 released from endothelial cells, also play a role in the regulation of blood pressure. (ADH = antidiuretic hormone.) Cerebral Medullary hemispheres adrenergic nerve receptors Pituitary gland Medula Transmission ADH secretion Increated cardiac output Spinal Heart cord Vasoconstriction Adrenaline and noradrenaline release Endothelin-1 Blood Adrena vessel Nitric oxide (NO) Prostaglandins Vasodilation gland Aldosteron Ronin Anglotensinogen release Kidney Anglotensin I Anglotensin- Fluid converting retention enryme Aorta Anglotensin I Refer to the Australian Medicines Handbook (available through the UTas data bases) and identify how each of these classes of medicines contribute to lowering blood pressure. Medicine Class Sitels of Mechanism of action and determinant of blood pressure Action affected ACE inhibitors ARBS Beta-blockers Calcium Channel Blockers Diuretics