Valvular Disease

Question 1

What are the primary actions of Angiotensin II?

Answer 1

1. Stimulation of vascular smooth muscle —> constriction of arteries, arterials, and veins, resulting in increased resistance to flow from LV (increased afterload)
2. Release of vasopressin (ADH) —> reduction in urine production and further stimulation of vascular smooth muscle (increased afterload)
3. Increased thirst —> increased water consumption —> expansion of blood volume —> increased preload
4. Decreased norepinephrine uptake from pre ganglion in sympathetic synapses —> increased circulating norepinephrine —> stimulation of vascular smooth muscle—> vasoconstriction (increased afterload), increased HR, down regulation of beta 1 receptors
5. Promotion of vascular smooth muscle growth —> arteriolar narrowing nad myocardial hypertrophy
6. PRoduction of free oxygen radials —> cell replacement by fibrosis
7. Production of aldosterone by zona glomerulosa of adrenal cortex —> NaCl retention by distal convoluted tubules —> water retention —> decreased urine production, increase in blood volume (increased preload) + loading of high pressure baroreceptors with NA/K ATPase, which interferes with proper function of baroreceptors, decreases vagal efferent traffic and causes tachycardia