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How do you diagnosis hypertension?
Blood pressure over >140/90
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BP =
- CO x TPR
- cardiac output(CO) and Total physical response of arterioles/postcapillary venues/ heart
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Types of antihypertensive drugs
- diuretics*
- angiotensin inhibitors (ACE - I and ARB)*
- Beta Blockers
- Centrally acting sympatholytics
- peripherally acting sympatholytic
- Ca2+ channel blockers*
- Orally active vasodilators
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Three classified into three broad categories related to their sites and mechanisms of action
- Thiazides
- Loop Diuretics
- K+ Sparing
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Simplified mechanism of action of diuretics
cause Na+ excretion and reduce fluid volume by inhibiting electrolyte transport in the renal tubules
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Simplified mechanism of action of Loop Diuretics
Transport by thick ascending limb cells. Model for ion transport by thick ascending limb. this segment, also referred to as the diluting segment, is impermeable to water, and thus the tubular lumen concentration of ions decreases
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simplified mechanism of action of thiazide Diuretics
Transport by distal convoluted tubule cells. Model for a distal convoluted tubule cell. As in the case for the thick ascending limb, this segment is relatively impermeable to water
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K+ Sparing Diuretics simplified mechanism of action
Transport by principal cells of the collecting tubule. The principal cell contains both Na+ and K+ channels in the apical cell membrane. The Na+ channel in the apical cell membrane depolarizes the membrane and provides an asymmetrical transepithelial voltage profile that favors K+ secretion
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Diuretics Clinical Implications
- Initial therapy for hypertension
- Initially: Increase in urinary water and electrolyte exertion, decrease in plasma volume and CO
- After several days: Normal CO and decrease in TPR
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Adverse Effects of Diuretics
- Hypokalemia
- Dilutional Hyponatremia
- Hypomagnesemia
- Hypercalcemia with thaizide diuretics
- Hypocalcemia with loop diuretics
- Hypersensitivity
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Types of Renin - Angiotensin Inhibitors
- Ace Inhibitors
- Angiotensin Receptor Blockers
- Renin Inhibitors
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Mechanism of action of ACE I
reversibly inhibit Ace and reduce blood pressure by inhibiting angiotensisn II formation
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Mechanism of Action of ARB
reversibly bind to the ATI subtype of angiotensin II receptors in blood vessels and other tissues
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What does angiotnesin II do?
Raises blood pressure when blood pressure falls
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Renin- Angiotensin-Aldosterone system
- 1.Blood pressure falls
- 2. Renin converts Angiotensinogen to Angiotensin I
- 3.Angiotensin Converting Enzyme converts Angiotensin I to Angiotensin II
- 4. Angiotensin II increases blood pressure and also activates aldosterone
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when to use ACE inhibitors
when patient has other risk factors such as heart failure, postmycocardial infarction, diabetes, kidney disease and stroke
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ACE - I adverse effects
dry cough, hyperkalemia, hypotension
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ARB adverse effects
hyperkalemia, hypotension
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Ca2+ channel Blocker mechanism of action
Inhibit the inward movement of Ca2+ through the L-type voltage -dependent Ca2+ channels
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Adverse effects of Ca 2+ channel Blockers
Cardiodepression, hypotension, headache, dizziness, peripheral edema
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