Angiotensin II

• Renin-angiotensin-aldosterone system (RAAS) / angiotensin II

  • hypotension -> decrease in renal perfusion -> release of renin -> cascade of chemical interactions -> producing angiotensin II
  • angiotensin II causes:
  • production of aldosterone and ADH (H2O conservation -> increase in volume)
  • stimulates thirst (drinking -> increase in volume)
  • increase in vasoconstriction
  • increase in sympathetic drive
• Renin-angiotensin-aldosterone system (RAAS) / angiotensin II

  1. starts with low blood pressure -> organ perfusion is compromised
  2. when the kidney is hyperperfused, it releases a hormone called renin, which acts on a prohormone which is produced by the liver called angiotensinogen
  3. renin converts angiotensinogen into angiotensin I
  4. the lungs releases ACE - Angiotensin Converting Enzyme
  5. ACE converts angiotensin I into angiotensin II
• Renin-angiotensin-aldosterone system (RAAS) / angiotensin II

  • has a number of different actions
  • switches on sympathetic activity
  • increases TPR
  • increases HR
  • increases inotropy
  • increases venoconstraction -> increases venous return -> increases pre-load -> increases SV
  • stimulates adrenal cortex to release aldosterone -> acts on kidneys to enhance water conservation
  • acts on arteriole smooth muscle -> vasoconstriction -> increases TPR
  • acts on posterior pituitary gland to release ADH -> increases water conservation to maintain blood volume