Exam

Renin-Angiotensin System

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Renin-Angiotensin System, Renin, Angiotensin, Angiotensinogen, Angiotensin Converting Enzyme

  • Physiology
  • Overall Process
  1. Step 1: Renin release
    1. Stimulators of renin release
      1. Kidney detects decreased effective blood flow
      2. Increased sympathetic tone
      3. Renal Artery Stenosis
    2. Renin secreted from renal cortex
      1. Secreted from juxtaglomerular cells
      2. Cells located at afferent arteriole of glomerulus
  2. Step 2: Renin mediated step
    1. Renin cleaves Angiotensinogen to Angiotensin I
  3. Step 3: Angiotensin-converting enzyme (ACE) mediated
    1. Angiotensin I converted by ACE to Angiotensin II
    2. Conversion by ACE occurs in pulmonary vasculature
  4. Step 4: Angiotensin II Effects
    1. Sodium and water retention
      1. Stimulates aldosterone secretion
      2. Directly affects renal tubule
    2. Vasomotor tone balance
      1. Angiotensin II is a potent Vasoconstrictor
        1. Increases systemic vascular resistence
        2. May be Norepinephrine mediated
      2. Antagonist to nitric oxide (potent vasodilator)
  • Physiology
  • Angiotensin II Effects
  1. Increases oxygen demand
  2. Increases coronary and renal Vasoconstriction
  3. Increases Preload and Afterload
  4. Predisposes to Left Ventricular Hypertrophy
  5. Increases Catecholamine release (e.g. Norepinephrine)
  6. Increases aldosterone
  • Agents that decrease Angiotensin II levels
  • References
  1. Rose (1987) Pathophysiology of Renal Disease, p. 474-7
  2. Bicket (2002) Am Fam Physician 66(3):461-8 [PubMed]