ANS Control of Blood Pressure Flashcards
What is systolic blood pressure?
Pressure inside the arteries when the heart pumps
What is diastolic blood pressure?
Pressure when the heart relaxes between beats
Quantitative definitions of HTN
-Diastolic over 80
-Systolic over 130
-Resting blood pressure (SBP-DBP) over 65
-Two or more measurements of blood pressure
Consequences of HTN
-Heart failure
-Coronary artery disease
-Angina/ischemia
-MI
-Kidney disease/failure
-Stroke
-Vision loss
Risk factors associated with HTN
-Aging
-Genetics
-Diabetes
-Obesity
-High sodium intake
-Low potassium intake
-Lack of exercise
-Excess alcohol intake
-Stress
-Reduced number of nephrons (age)
What percent of HTN patients have primary/essential HTN?
~90%
Causes of secondary HTN
-Aldosteronism
-Bad kidneys
-Cushing’s/coarctation
-Drugs
-Endocrine disorders
How are HTN and diabetes related?
-Lifestyles that lead to HTN can also lead to diabetes
-Diabetic nephropathy can cause HTN
-Glucose and fat can lead to vascular damage
Nonpharmacologic strategies to reduce the risk of HTN
-Weight loss
-Adopt DASH diet
-Salt reduction
-Exercise
-Reduce alcohol consumption
-Smoking cessation
Pharmacologic strategies to reduce the risk of HTN
-Reduce the systolic blood pressure
-Reduce cardiac output
-Reduce vascular resistance through vasodilation of decreasing the blood volume
Which nonpharmacologic strategy has the greatest impact on the management of hypertension
Weight loss
Why are HTN medications generally harder to stay compliant with?
-Hypertension is asymptomatic
-Requires daily drug treatment
-Many of these drugs can have undesirable side effects such as ED in men, general sexual dysfunction and serious CNS effects such as depression or nighmares
How does the baroreceptor reflex respond to a decrease in blood pressure?
Activates sympathetic fibers that:
-innervate the heart (beta 1) which increase heart rate
-Innervate the blood vessels (alpha 1) resulting in vasoconstriction
-Inhibits vagus (PSNS)
-Net result is an increase in blood pressure
How does the baroreceptor reflex respond to an increase in blood pressure?
-Inhibits sympathetic fibers
-Activates the vagus (PSNS) which decreases heart rate
-Net result is a decrease in BP
What is the mechanism of action of phenylephrine?
-Activates the alpha 1 receptor which leads to vasoconstriction
-Baroreceptor reflex activates causing a decrease in heart rate
-Overall increase in systolic pressure and decrease in heart rate
What is the mechanism of action of epinephrine?
-Activates the alpha 1 receptor which leads to vasoconstriction
-Activates the beta 2 receptor which leads to vasodilation
-Activates the beta 1 receptor which causes a positive inotropic and chronotropic effects
-Activation of the baroreceptor reflex mitigates the direct effects
-Overall an increase in systolic pressure, pulse pressure, and heart rate
What is the mechanism of action of isoproterenol?
-Activates the beta 2 receptor which causes vasodilation
-Activates the beta 1 receptor which leads to positive inotropic and chronotropic effects
-Activation of the baroreceptor reflex enhances the direct effects
-Overall there would be a decrease in diastolic pressure and an increase in pulse pressure and heart rate
Targets for antihypertensive drugs
-Heart
-Resistance of arterioles
-Resistance of veins
-Kidney
Classes of antihypertensive medications
-Diuretics
-Sympatholytics
-Vasodilators
-Renin-angiotensin-aldosterone system antagonists
Examples of diuretics
-Thiazides
-Potassium-sparing diuretics
-Loop diuretics
Physiologic action of diuretics
Decreases circulating volume
Examples of sympatholytics
-Beta blockers
-Combined alpha and beta blockers
-Central alpha 2 agonists
-Peripheral alpha 1 antagonists
Physiologic action of beta blockers
-Decrease heart rate
-Cardiac contractility
-Renin secretion
Physiologic action of combined alpha and beta blockers
-Decrease heart rate
-Cardiac contractility
-Renin secretion
-Smooth muscle relaxation
Physiologic action of central alpha 2 agonists
Decrease in sympathetic tone
Physiologic action of peripheral alpha 1 antagonists
Vascular smooth muscle relaxation
Examples of vasodilators
-Calcium channel blockers
-Direct vasodilators
Physiologic action of vasodilators
Decrease in peripheral vascular resistance
Examples of RAAS antagonists
-Angiotensin-converting enzyme inhibitors
-Angiotensin 2 receptor blockers
-Direct renin inhibitors
Physiologic action of RAAS antagonists
-Decrease in peripheral vascular resistance
-Decrease in sodium retention
Beta-blocker concurrent indications
-Heart failure
-Postmyocardial infarction
-Angina
-Cardiac arrhythmia
Diuretic concurrent indications
-Heart failure
ACE inhibitor concurrent indications
-Heart failure
-Postmyocardial infarction
-Diabetes
-Chronic kidney disease
Angiotensin 2 receptor blocker concurrent indications
-Heart failure
-Postmyocardial infarction
-Diabetes
-Chronic kidney disease
Aldosterone antagonist concurrent indications
-Heart failure
-Postmyocardial infarction
Calcium channel blocker concurrent indications
-Diabetes
Examples of alpha 1 antagonists
-Prazosin
-Terazosin
-Doxazosin
Metabolism of alpha 1 antagonists
metabolized extensively and excreted in yhe bile
Therapeutic indications of alpha 1 antagonists
-Hypertension
-Benign prostatic hyperplasia
Side effects of alpha 1 antagonists
-First-dose phenomenon
-Postural hypotension
-Syncope
Examples of alpha 2 receptor agonists
-Clonidine
-Methyldopa
-Guanabenz
-Guanfacine
-Brimonidine
-Apraclonidine
-Tizanidine
How do alpha 2 agonists work?
-Decreases norepinephrine release in the brain which leads to a decrease in heart rate, contractility, renin release, and vasoconstriction
Which alpha 2 agonist is a prodrug?
Methyldopa
Pharmacological effects of beta blockers
-Decreased cardiac output and heart rate
-Reduced renin release
-Increased VLDL, decrease HDL
-Inhibit lipolysis
-Inhibit compensatory glycogenolysis and glucose release in response to hypoglycemia
-Increase bronchia airway resistance
What are the selective beta 1 adrenergic receptor antagonists?
-Metoprolol
-Bisoprolol
-Atenolol
-Esmolol
-Nebivolol
Side effects of beta blockers
-Bradycardia
-AV block
-Sedation
-Mask symptoms of hypoglycemia
-Withdrawal symptoms
Contraindications of beta blockers
-Asthma
-COPD
-Congestive heart failure
Which type of beta blocker is preferred for HTN?
Beta 1 blocker
Mixed beta adrenergic antagonists
-Carvedilol
-Labetolol
Effect of mixed beta adrenergic antagonists
Decrease total peripheral resistance via decreasing alpha mediated vasoconstriction resulting in lower blood pressure; prevent reflex tachycardia
Clinical use of labetolol
Hypertensive emergencies, pheochromocytoma
Clinical use of carvedilol
Heart failure
