MECHANISMS FOR CONTROLLING BLOOD PRESSURE In both normal and hypertensive individuals,cardiac output and peripheral resistance are controlled mainly by two overlapping control mechanisms:the baroreflexes mediated by the sym-pathetic nervous system, and the renin-angiotensin-aldosterone system
MECHANISMS FOR CONTROLLING BLOOD PRESSURE ◼ In both normal and hypertensive individuals, cardiac output and peripheral resistance are controlled mainly by two overlapping control mechanisms: the baroreflexes mediated by the sym- pathetic nervous system, and the renin-angiotensin-aldosterone system
Central nervous systom Stress Nucleus tractus soltarius Carotd chemoreceptors Cardiac output Vascular resistance Arteral efferents Na'K"Ca baroreceptors Atrial natriuretic peptde Cardicpumonary Sympathetic barorecoptors Endothelal factors Preload I (NaCl and H,0) Plasma renin angictensin ll Prostaglandins Kinins Renal regulation of NaCl and H.o
TREATMENT STRATEGIES Mild hypertension can often be controlled with a single drug. More severe hypertension may require treatment with several drugs that are selected to minimize adverse effects of the combined regimen. Treatment is initiated with any of four drugs depending on the individual patient:a diuretic, a [beta-blocker,an ACE inhibitor,or a calcium channel blocker
TREATMENT STRATEGIES ◼ Mild hypertension can often be controlled with a single drug. ◼ More severe hypertension may require treatment with several drugs that are selected to minimize adverse effects of the combined regimen. ◼ Treatment is initiated with any of four drugs depending on the individual patient: a diuretic, a •beta-blocker, an ACE inhibitor, or a calcium channel blocker
Beta-Blockers Decrease heart rate,stroke volume Centrally acting drugs Receptors 1,-imidazoline-receptorAgorists Decrease central symmpathetic outflow -) Norepinephrine Central sympathetic outfow o,-Receptors K'channel openers AT,-Receptors K'Channel n Alpha-Blockers Calcium channel blockers ACE inhibitors Calciun AT:-Antagonists channel(L-type) B2-Receptors Relaxation Vascular smooth Diuretics" muscle cell Thiazides (- Na non (-) 45a Loop diuretics(-)
DIURETICS Diuretics are currently recommended as the first-line drug therapy for hypertension. Low-dose diuretic therapy is safe and effective in preventing stroke, myocardial infarction,congestive heart failure and total mortality
DIURETICS ◼ Diuretics are currently recommended as the first-line drug therapy for hypertension. ◼ Low-dose diuretic therapy is safe and effective in preventing stroke, myocardial infarction, congestive heart failure and total mortality