Module 4, Section 1

• Hypertension


  Chronically high blood pressure
• Damage caused by hypertension

  • Damage to blood vessels in the kidneys, heart, and brain

  
• Antihypertensive drugs


  Drugs used to control blood pressure

  
• Control of blood pressure by use of antihypertensive drugs has been shown to reduce damage to blood vessels, and thus, reduce mortality and hospitalization rates for vascular disease

  
• Blood pressure


  The force the circulating blood exerts on the arterial walls

  
• Normal blood pressure value in a young adult is 120/80

  
• Cardiac output (CO)


  The volume of blood that is pumped by each ventricle per unit time
• Heart rate (HR)

  The number of heartbeats per unit time
• Stroke volume (SV)


  The amount of blood pumped from a ventricle per unit time
• Hypertension is usually silent, and the person is not aware they have the disease
• Primary (essential) hypertension


  The most common type of hypertension, with no identifiable cause
• Secondary hypertension


  Hypertension caused by an underlying disease
• Lifestyle changes to control hypertension

  • Reduced weight
  • Regular exercise
  • Low salt diet
  • Reduced alcohol consumption
  • Stop smoking
  • Stress management
• Diuretics


  Drugs that affect the fluid volume of the blood by influencing sodium and water retention in the kidney

  
• Urine production in the kidney


  1. Renal corpuscle filters the blood

  2. Renal tubule reabsorbs useful materials and water back into the blood

  3. Collecting duct transfers urine to the ureter

  
• Major classes of diuretics

  • Loop diuretics
  • Thiazide diuretics
  • Potassium sparing diuretics
• Loop diuretics


  Act within the thick ascending limb of the loop of Henle, decreasing reabsorption of NaCl

  
• Thiazide diuretics


  Act on the distal convoluted tubule, decreasing NaCl reabsorption
• Potassium sparing diuretics


  Increase excretion of sodium and water, decrease excretion of potassium
• Aldosterone antagonists


  Competitively block aldosterone, leading to increased sodium and water excretion

  
• Sodium channel blockers


  Cause a decrease in sodium reabsorption, increasing the volume of water in the urine
• Thiazide diuretics would be the most applicable diuretic to prescribe to the 83-year-old male patient with hypertension and normal urine profile
• β1 blockers


  Decrease activity of the sympathetic nervous system by blocking β1-adrenergic receptors, reducing cardiac output
• Alpha blockers


  Bind to and block alpha receptors in the peripheral arterioles and capacitance vessels, reducing vasoconstriction

  
• β1 receptor blockade


  Reduction of cardiac output

  
• Clinical use of β1 blockers

  • Reduction in stroke and other serious cardiovascular problems
  • Less effective than diuretics in the elderly and in African Americans

  
• Adverse effects of beta blockers

  Blockade of β2 receptors in the bronchi, causing bronchospasm

  
• Alpha blockers


  Bind to and block alpha receptors in the peripheral arterioles and capacitance vessels, reducing vasoconstriction and peripheral resistance

  
• Clinical use of alpha blockers

  • Adverse effects have limited the clinical use
• Adverse effects of alpha blockers

  Headache, orthostatic hypotension, dizziness, loss of consciousness due to a dramatic drop in blood pressure

  
• Centrally-acting drugs


  Act on the central nervous system, decreasing sympathetic nervous system outflow to blood vessels, reducing resistance and blood pressure
• Clinical use of centrally-acting drugs

  • Adverse effects have limited the use
• Adverse effects of centrally-acting drugs

  Similar to alpha blockers, including headache, orthostatic hypotension, dizziness
• Vasodilators


  Drugs that widen or dilate the blood vessels
• Calcium channel blockers


  A type of vasodilator that decreases extracellular calcium reaching vascular smooth muscle, causing relaxation and vasodilation
• Vascular smooth muscle contraction

  1. Calcium enters cell through channel

  2. Calcium binds to calmodulin

  3. Calcium-calmodulin activates myosin kinase

  4. Myosin phosphorylation causes contraction
• Renin-angiotensin system (RAS)

  Hormone system that regulates blood pressure and fluid balance

  
• RAS activation


  1. Renin converts angiotensinogen to angiotensin I

  2. ACE converts angiotensin I to angiotensin II

  3. Angiotensin II causes vasoconstriction and aldosterone secretion, increasing blood pressure

  
• ACE inhibitors


  Inhibit conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion

  
• Clinical use of ACE inhibitors

  • Do not cause sexual dysfunction
  • Can be used in asthma
  • Do not alter carbohydrate or lipid metabolism, can be used in diabetes