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37 Cards in this Set
- Front
- Back
What is rapid control of BP normally controlled by
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Baroreceptor Reflex-- the baroreflex monitors and corrects changes in BP within a matter of seconds by altering cardiac output and peripheral vascular resistance
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What manages the long term control of BP
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Accomplished primarily by the kidney via fluid balance
Changes in BP through the renal handling of fluid and electrolytes usually takes place over a period of several hours or days |
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What are some local factors/systems than can play a role in controlling BP
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1. Circulating Catecholamines (adrenal gland)
2. Arginine-vasopressin (pituitary gland) 3. Angiotensin II |
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GIve the BP equations
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BP = CO x PVR
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Describe secondary HTN
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HTN is attributed to some abnormality such as renal artery stenosis, tumors, endocrine disorders, or cerebral damage
Correct the pathology to decrease HTN |
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Describe Primary (Essenial) HTN
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No known cause of HTN--treat the HTN itself
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Possible mechanisms for Essential HTN
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Environmental factors such as stress, diet, hormonal factors, genetics, & decreased baroreceptor sensitivity act on the hypothalamus and brainstem causing exaggerated sympathetic outflow
Increased sympathetic outflow causing kidneys to fail to adequately adjust fluid and electrolyte volume Also causes increased CO and or increased PVR--increasing HTN The contd increases in HTN acts as a vicious cycle going back and further damaging the baroreceptor reflex and integrity of the vasculature |
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What are the 5 drugs used to treat HTN
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1. Diuretics
2. Smpatholytic drugs 3. Vasodilators 4. Renin-angiotensin system inhibitors 5. Calcium Channel blockers |
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How do diuretics decrease HTN
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Mainly increase the formation and excretion of urine
Increase the renal excretion of water and sodium, thus decreasing the volume of fluid within the vascular system and decreasing pressure in the vessels Often the 1st type of antihypertension drugs used for mild-moderate HTN More specifically, diuretics act directly on the kidneys to increase water and sodium excretion |
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What are 3 major classes of diuretics
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1. Thiazide
2. Loop Diuretics 3. Potasium Sparing |
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How do thiazide diuretics work
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Act primarily on the early portion of the distal tubule of the nephron, where they inhibit sodium reabsorption
By inhibiting sodium reabsorption, more sodium is retained in the nephron, creating an osmotic force that also retains more water in the nephron More sodium and water and passed through the nephron and excreted |
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What is the major thiazide drug type
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1. Hydrochlorothiazide (HCTZ or Esidrix)
Most frequently used type of diuretic |
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Mechanism of Loop Diuretics
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Act primarily on the ascending loop of Henle
Inhibit the reabsorption of sodium and chloride from the nephron--therefore preventing the reabsorption of the water that follows these electrolytes |
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What is the major Loop Diuretic
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Furosemide (Lasix)
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What is the mechanism of potassium sparing diuretics
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Able to prevent secretion of K+ into the distal tubule
Normally a sodium potassium exchange occurs in the distal tubule--where sodium is reabsorbed and potassium is excreted K+-sparing agents interfere with this exchange so that K+ is spared from secretion and sodium remains in the tubule, where it is excreted Dont produce the same diuretic effect but have the benefit of preventing hypokalemia |
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Serious side effects of Diuretics
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1. Volume depletion: may cause reflex increase in CO or TPR (baroreflex) or activate the renin-angiotension system putting increase demand on cardiac muscle
2. Electrolyte imbalance--hypokalemia ma result from thiazide and loop diuretic use -Hyperkalemia can result from K-sparing diuretic use 3. Impaired Glucose Metabolism: thiazide diuretics may cause pts with DM to have hyperglycemia |
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Give the 5 categories of Sympathlytic drugs used for HTN
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1. Beta Blockers
2. Alpha-Adrenergic Blockers 3. Presynaptic adrenergic NT depletors 4. Centrally acting drugs 5. Ganglionic Blockers |
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Mechanism of action of Vasodilators
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Directly vasodilate the peripheral vasculature to decrease peripheral vascular resistance
Exert an inhibitory effect on vascular smooth muscle cells by increasing the intracellular production of 2nd messengers such as cycli guanosine monophosphate (cGMP) Increased amts of cGMP inhibit the fxn of the contractile process in the vascular smooth-muscle cell, thus leading to vasodilation |
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What are the 2 main vasodilators
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1. Minoxidil (Loniten)-- for maintenance use (hydralazine is another one)
2. Nitroprusside (Nipride/Nitropress)-- given orally for emergent use |
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When are vasodilators typically used with HTN
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Not generally as first choice--if diuretics and beta blockers don't work
Used during emergency |
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Give adverse effects of Vasodilators
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1. Reflex tachycardia
2. Dizziness 3. Hypotension 4. Weakness 5. Nausea 6. Fluid Retention 7. HA |
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What is the job of the renin-angiotensin system
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Help regulate vascular tone in various organs and tissues
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What is renin
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An enzyme produced in the kidney
When BP falls renin is released from the kidneys into the systemic circulation |
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What is angiotensinogen
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A peptide that is produced by the liver and circulates continually in the bloodstream
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Describe the Renin-Angiotensin System
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Angiotensinogen circulating contacts renin and is transformed into Angiotensin I
Circulating angiotensin I is transformed by angiotensin-converting enzyme to angiotensin II The converting enzyme is located in the vasculature of many tissues--especially the lungs Angiotensin II is an extremely potent vasoconstrictor--thus the fall in BP that activates the renin-angiotensin system is rectified by angiotensin II |
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Other than vasoconstricting, what else does angiotensin II affect
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Increases aldosterone secretion from the adrenal cortex
Aldosterone directly increases sodium reabsorption from the kidneys--creating osmotic forces in the kidneys that encourage water reabsorption, helping maintain plasma volume |
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Why is activation of the renin-angiotensin system bad for pts with hypertension
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1. Excess production of angiotensin II produces vasoconstriction
2. Angiotensin II is a powerful stimulant of vascular growth, and sustain production of AT II results in the thickening and hypertrophy of the vascular wall--further increasing HTN |
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What are the two drug types that block the Renin-Angiotensin system
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1. ACE inhibitors (angiotensin converting enzyme)-- inhibit this enzyme which converts angiotensin I too angiotensin II
2. Angiotensin II blockers/antagonists-- block AT II receptors |
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Give the specific use and advantage of the 2 drugs that block the renin-angiotensin system
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Lower incidence of adverse side effects such as reflex tachycardia and OH vs other anti-HTN drugs--allow them to be used for more long term control of BP
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Give the major ACE inhibitor and Angiotensin II blocker drugs
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ACE Inhibitor: Lisinopril or Zestril
AT II inhibitor: Losartan or Cozaar |
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Give two major mechanism of how Calcium Channel Blockers decrease HTN
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Calcium helps activate the contractile element in smooth muscle cells--thus drugs that block calcium entry into vascular smooth muscle will inhibit the contractile process--leading to vasodilation and decreased vascular resistance
2. Calcium channel blockers also tend to decrease HR and myocardial contraction-- |
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What are Calcium Channel Blockers mainly used for
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Treating angina pectoris and cardiac arrythmias
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Give a possible adverse effect of Calcium Channel blockers
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Some (especially short acting) are associated with increased risk of MI in certain patients
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What are the primary side effects to watch out for during mobility and exercise in pts with HTN
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1. OH
2. Hypotnesion D/t drugs |
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What type of activities should PTs be cautious with dealing with pts on anti-HTN drugs
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1. Whirlpool
2. Exercise Anything that causes an increase in body temperature cause this will cause vasodilation--especially if on vasodilation |
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When should PTs use different methods other than vital signs to gauge exercise intensity
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When pt is one Beta blockers cause these will blunt the increase in HR normally seen with exercise
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What type of education does PT need to do consistently with pts on ANTI-HTN drugs
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Make sure they take there drugs and explain that HTN is a silent killer
pts may not want to take drugs cause they actually feel worse when on the bc of the side effects |