PHARMACO U7: ANTIHYPERTENSIVE
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Questions and Answers

What triggers the release of renin in the kidney?

  • Sympathetic stimulation of β2-adrenoceptors (correct)
  • Reduced arterial pressure (correct)
  • Decreased sodium intake
  • Increased arterial pressure

    • What is the primary mechanism of diuretics in lowering blood pressure?

  • Constricting blood vessels
  • Depleting body sodium stores (correct)
  • Increasing cardiac output
  • Vasodilation

    • Which type of diuretics acts promptly by blocking sodium and chloride reabsorption in the kidneys?

  • Thiazide diuretics
  • ACE inhibitors
  • Loop diuretics (correct)
  • Potassium-sparing diuretics

    • What is the effect of thiazide diuretics on potassium levels in the blood?

    <p>Hypokalemia</p> Signup and view all the answers

    Which type of diuretics is used to reduce potassium loss in the urine?

    <p>Potassium-sparing diuretics</p> Signup and view all the answers

    What is the primary mechanism of β-blockers in lowering blood pressure?

    <p>Decreasing cardiac output</p> Signup and view all the answers

    What is the effect of β-blockers on the release of renin from the kidneys?

    <p>Decrease the release of renin</p> Signup and view all the answers

    What is the mechanism of action of spironolactone and eplerenone?

    <p>Block aldosterone receptor in the renal collecting tubule</p> Signup and view all the answers

    What is the effect of nebivolol on blood vessels?

    <p>Vasodilation</p> Signup and view all the answers

    What is the primary mechanism of Angiotensin II in controlling blood pressure?

    <p>Vasoconstriction</p> Signup and view all the answers

    Which type of β-blockers are contraindicated in patients with asthma?

    <p>Nonselective β-blockers</p> Signup and view all the answers

    What is a common side effect of β-blockers?

    <p>Bradycardia</p> Signup and view all the answers

    Which class of antihypertensive drugs blocks the enzyme ACE which cleaves angiotensin I to form angiotensin II?

    <p>ACE inhibitors</p> Signup and view all the answers

    What is a rare but potentially life-threatening reaction to ACE inhibitors?

    <p>Angioedema</p> Signup and view all the answers

    What is a side effect of calcium channel blockers?

    <p>All of the above</p> Signup and view all the answers

    Which type of α-Adrenoceptor blocking agents produce a competitive block of α1-adrenoceptors?

    <p>Prazosin, doxazosin, and terazosin</p> Signup and view all the answers

    What is the main use of carvedilol?

    <p>Treatment of heart failure</p> Signup and view all the answers

    What is a side effect of ACE inhibitors?

    <p>Dry cough</p> Signup and view all the answers

    What is a concern when discontinuing β-blockers in patients with ischemic heart disease?

    <p>Angina, myocardial infarction, and sudden death</p> Signup and view all the answers

    Which type of β-blockers may disturb lipid metabolism, decreasing high-density lipoprotein cholesterol and increasing triglycerides?

    <p>Noncardioselective β-blockers</p> Signup and view all the answers

    What happens to blood pressure when we stand up suddenly after lying down?

    <p>It drops</p> Signup and view all the answers

    Which of the following is responsible for reflexive vasoconstriction?

    <p>Baroreceptors</p> Signup and view all the answers

    What happens to blood pressure when the kidneys retain body water?

    <p>It increases</p> Signup and view all the answers

    What is the effect of cold on blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    Which of the following chemicals increases blood pressure by causing vasoconstriction?

    <p>Nicotine</p> Signup and view all the answers

    What is the role of the renin-angiotensin-aldosterone system (RAAS) in controlling blood pressure?

    <p>Long-term regulation</p> Signup and view all the answers

    What is the equation that describes blood pressure?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the response of the baroreflex to a fall in blood pressure?

    <p>Increased sympathetic output</p> Signup and view all the answers

    What is the primary mechanism of action of vasodilators?

    <p>Relaxation of vascular smooth muscle</p> Signup and view all the answers

    What is the effect of a diet low in salt, saturated fats, and cholesterol on blood pressure?

    <p>It helps to prevent hypertension</p> Signup and view all the answers

    Which of the following β-blockers is often used in combination with hydralazine?

    <p>Propranolol</p> Signup and view all the answers

    What is the primary use of methyldopa?

    <p>Management of hypertension in pregnancy</p> Signup and view all the answers

    Which of the following is a potent vasoconstrictor chemical?

    <p>Angiotensin II</p> Signup and view all the answers

    What is a common side effect of methyldopa?

    <p>Sedation and drowsiness</p> Signup and view all the answers

    What is the primary mechanism of action of clonidine?

    <p>Inhibition of adrenergic outflow from the CNS</p> Signup and view all the answers

    Which of the following drugs is used topically to treat male pattern baldness?

    <p>Minoxidil</p> Signup and view all the answers

    Which of the following β-blockers is used in the management of heart failure?

    <p>Carvedilol</p> Signup and view all the answers

    What is the primary use of labetalol?

    <p>Management of gestational hypertension and hypertensive emergencies</p> Signup and view all the answers

    What is the force that keeps blood circulating continuously even between heartbeats?

    <p>Blood pressure</p> Signup and view all the answers

    What is the unit of measurement for blood pressure?

    <p>Millimeters of mercury</p> Signup and view all the answers

    What is the pressure in the arteries at the peak of ventricular contraction?

    <p>Systolic pressure</p> Signup and view all the answers

    What is the formula for Blood Pressure (BP)?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the role of the sympathetic division of the autonomic nervous system in blood pressure?

    <p>It increases blood pressure by causing vasoconstriction</p> Signup and view all the answers

    What is the term for the narrowing of the blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the amount of blood pumped by each ventricle in one contraction?

    <p>Stroke Volume</p> Signup and view all the answers

    What is the amount of blood pumped out of the left ventricle per minute?

    <p>Cardiac Output</p> Signup and view all the answers

    What is the pressure in the arteries when the ventricles are relaxing?

    <p>Diastolic pressure</p> Signup and view all the answers

    What is the equation that describes blood pressure?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the role of the sympathetic division of the autonomic nervous system in blood pressure?

    <p>Increasing blood pressure</p> Signup and view all the answers

    What is the term for the narrowing of the blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the unit of measurement for blood pressure?

    <p>Millimeters of mercury (mm Hg)</p> Signup and view all the answers

    What is the amount of blood pumped out of the left ventricle per minute?

    <p>Cardiac output</p> Signup and view all the answers

    What is the force that keeps blood circulating continuously even between heartbeats?

    <p>Blood pressure</p> Signup and view all the answers

    What is the amount of blood pumped by each ventricle in one contraction?

    <p>Stroke volume</p> Signup and view all the answers

    What is the mechanism of action of clonidine?

    <p>Acts centrally as an α2-agonist to decrease sympathetic outflow</p> Signup and view all the answers

    Which of the following drugs is used to treat hypertension in pregnancy?

    <p>Methyldopa</p> Signup and view all the answers

    What is the primary mechanism of action of vasodilators?

    <p>Relaxation of vascular smooth muscle, primarily in arteries and arterioles</p> Signup and view all the answers

    Which of the following drugs is used topically to treat male pattern baldness?

    <p>Minoxidil</p> Signup and view all the answers

    What is the common side effect of methyldopa?

    <p>Sedation and drowsiness</p> Signup and view all the answers

    Which of the following β-blockers is used in the management of heart failure?

    <p>Carvedilol</p> Signup and view all the answers

    What is the primary use of labetalol?

    <p>Management of gestational hypertension and hypertensive emergencies</p> Signup and view all the answers

    What is the effect of hydralazine treatment?

    <p>Hypertrichosis</p> Signup and view all the answers

    What happens to blood pressure when blood volume suddenly decreases, as in hemorrhage?

    <p>It decreases</p> Signup and view all the answers

    Which part of the nervous system plays a role in regulating blood pressure when we exercise vigorously?

    <p>Sympathetic nervous system</p> Signup and view all the answers

    What is the effect of heat on blood vessels?

    <p>Vasodilation</p> Signup and view all the answers

    What is the role of the kidneys in regulating blood pressure?

    <p>To regulate blood volume and thus blood pressure</p> Signup and view all the answers

    What is the equation that describes blood pressure?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the response of the baroreflex to a sudden increase in blood pressure?

    <p>Decreased sympathetic and increased parasympathetic output</p> Signup and view all the answers

    What is the effect of nicotine on blood pressure?

    <p>It increases blood pressure</p> Signup and view all the answers

    What is the term for the widening of blood vessels?

    <p>Vasodilation</p> Signup and view all the answers

    What is the role of the autonomic nervous system in regulating blood pressure?

    <p>To regulate blood pressure through vasodilation and vasoconstriction</p> Signup and view all the answers

    What is the effect of epinephrine on blood pressure?

    <p>It increases blood pressure</p> Signup and view all the answers

    Which of the following is a consequence of decreased arterial pressure in the kidneys?

    <p>Release of renin</p> Signup and view all the answers

    What is the primary mechanism of angiotensin II in controlling blood pressure?

    <p>Vasoconstriction</p> Signup and view all the answers

    Which class of antihypertensive drugs reduces blood pressure by inhibiting the release of renin?

    <p>β-Adrenoreceptor Blockers</p> Signup and view all the answers

    What is the mechanism of action of thiazide diuretics?

    <p>Block Na/Cl transporter in the renal distal convoluted tubule</p> Signup and view all the answers

    Which type of diuretics is used in combination with thiazide diuretics to reduce potassium loss?

    <p>Potassium-Sparing Diuretics</p> Signup and view all the answers

    What is the effect of nonselective β-blockers on patients with asthma?

    <p>They are contraindicated due to blockade of β2-mediated bronchodilation</p> Signup and view all the answers

    What is a common side effect of β-blockers?

    <p>Fatigue, lethargy, and insomnia</p> Signup and view all the answers

    What is the effect of nebivolol on blood vessels?

    <p>Vasodilation</p> Signup and view all the answers

    Which type of β-blockers is contraindicated in patients with asthma?

    <p>Non-selective blockers of β1- and β2-receptors</p> Signup and view all the answers

    What is the mechanism of action of ACE inhibitors?

    <p>They block the enzyme ACE which cleaves angiotensin I to form angiotensin II</p> Signup and view all the answers

    What is the primary mechanism of ACE inhibitors in lowering blood pressure?

    <p>Inhibition of angiotensin II formation</p> Signup and view all the answers

    What is a rare but potentially life-threatening reaction to ACE inhibitors?

    <p>Angioedema</p> Signup and view all the answers

    Which type of antihypertensive drugs reduces blood pressure by blocking the aldosterone receptor?

    <p>Potassium-Sparing Diuretics</p> Signup and view all the answers

    What is the effect of calcium channel blockers on blood vessels?

    <p>They cause vasodilation</p> Signup and view all the answers

    What is the primary mechanism of action of α-Adrenoceptor blocking agents?

    <p>They produce a competitive block of α1-adrenoceptors</p> Signup and view all the answers

    What is the primary mechanism of loop diuretics in lowering blood pressure?

    <p>Blockage of sodium and chloride reabsorption</p> Signup and view all the answers

    What is a side effect of β-blockers that can reduce patient compliance?

    <p>Decreased libido and erectile dysfunction</p> Signup and view all the answers

    What is the effect of abrupt withdrawal of β-blockers in patients with ischemic heart disease?

    <p>It may cause angina and myocardial infarction</p> Signup and view all the answers

    What is the primary mechanism of action of aliskiren?

    <p>It directly inhibits renin and acts earlier in the renin-angiotensin-aldosterone system</p> Signup and view all the answers

    What is a common side effect of dihydropyridines, a class of calcium channel blockers?

    <p>Dizziness, headache, and a feeling of fatigue</p> Signup and view all the answers

    What is the purpose of blood pressure in the body?

    <p>To keep blood circulating continuously even between heartbeats</p> Signup and view all the answers

    What are the two arterial blood pressure measurements?

    <p>Systolic pressure and diastolic pressure</p> Signup and view all the answers

    How are blood pressure values reported?

    <p>In millimeters of mercury (mm Hg) with the higher systolic pressure written first</p> Signup and view all the answers

    What is the role of the sympathetic division of the autonomic nervous system in blood pressure?

    <p>Increasing blood pressure by causing vasoconstriction</p> Signup and view all the answers

    What is cardiac output?

    <p>The amount of blood pumped out of the left ventricle per minute</p> Signup and view all the answers

    What is peripheral resistance?

    <p>The amount of friction the blood encounters as it flows through the blood vessels</p> Signup and view all the answers

    What is the equation that describes blood pressure?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the term for the narrowing of the blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the primary mechanism of noncardioselective β-blockers in lowering blood pressure?

    <p>Decreasing renin release from the kidneys</p> Signup and view all the answers

    Which type of β-blockers are contraindicated in patients with asthma due to their blockade of β2-mediated bronchodilation?

    <p>Noncardioselective β-blockers</p> Signup and view all the answers

    What is the primary mechanism of action of ACE inhibitors in lowering blood pressure?

    <p>Blocking the enzyme ACE which cleaves angiotensin I to form angiotensin II</p> Signup and view all the answers

    What is a rare but potentially life-threatening reaction to ACE inhibitors?

    <p>Angioedema</p> Signup and view all the answers

    What is the primary mechanism of action of calcium channel blockers in lowering blood pressure?

    <p>Blocking the inward movement of calcium by binding to L-type calcium channels</p> Signup and view all the answers

    Which type of α-Adrenoceptor blocking agents produce a competitive block of α1-adrenoceptors?

    <p>Prazosin, doxazosin, and terazosin</p> Signup and view all the answers

    What is the primary use of carvedilol?

    <p>Treatment of heart failure</p> Signup and view all the answers

    What is a concern when discontinuing β-blockers in patients with ischemic heart disease?

    <p>Abrupt withdrawal may induce angina, myocardial infarction, and even sudden death</p> Signup and view all the answers

    What is the primary function of the Renin-Angiotensin-Aldosterone System (RAAS)?

    <p>To control blood pressure through vasoconstriction</p> Signup and view all the answers

    Which type of β-blockers may disturb lipid metabolism, decreasing high-density lipoprotein cholesterol and increasing triglycerides?

    <p>Noncardioselective β-blockers</p> Signup and view all the answers

    Which class of antihypertensive drugs is used to manage symptoms of heart failure and edema?

    <p>Diuretics</p> Signup and view all the answers

    What is a side effect of ACE inhibitors?

    <p>Dry cough</p> Signup and view all the answers

    What is the mechanism of action of thiazide diuretics?

    <p>Blocking Na/Cl transporter in the renal distal convoluted tubule</p> Signup and view all the answers

    Which type of β-blocker is also known to increase the production of nitric oxide, leading to vasodilation?

    <p>Nebivolol</p> Signup and view all the answers

    What is the effect of potassium-sparing diuretics on potassium levels in the blood?

    <p>Increased potassium levels</p> Signup and view all the answers

    Which type of diuretics is used in combination with loop diuretics and thiazides to reduce potassium loss?

    <p>Potassium-sparing diuretics</p> Signup and view all the answers

    What is the primary mechanism of Angiotensin II in controlling blood pressure?

    <p>Vasoconstriction</p> Signup and view all the answers

    Which class of antihypertensive drugs blocks the conversion of angiotensin I to angiotensin II?

    <p>ACE Inhibitors</p> Signup and view all the answers

    What is the effect of β-blockers on cardiac output?

    <p>Decrease cardiac output</p> Signup and view all the answers

    Which type of antihypertensive drug is often used in combination therapy with a variety of other antihypertensive agents?

    <p>Diuretics</p> Signup and view all the answers

    What is the primary mechanism by which the kidneys regulate arterial blood pressure?

    <p>By altering blood volume</p> Signup and view all the answers

    What is the effect of heat on blood vessels?

    <p>Vasodilation</p> Signup and view all the answers

    What is the response of the baroreflex to a sudden increase in blood pressure?

    <p>Decreased sympathetic and increased parasympathetic output</p> Signup and view all the answers

    What is the effect of nicotine on blood pressure?

    <p>Increases blood pressure</p> Signup and view all the answers

    What is the primary mechanism of controlling blood pressure in the short-term?

    <p>Neural factors</p> Signup and view all the answers

    What is the effect of angiotensin II on blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the role of the sympathetic nervous system in blood pressure regulation?

    <p>Increases blood pressure</p> Signup and view all the answers

    What is the effect of a diet low in salt, saturated fats, and cholesterol on blood pressure?

    <p>Decreases blood pressure</p> Signup and view all the answers

    What is the equation that describes blood pressure?

    <p>BP = CO x PR</p> Signup and view all the answers

    What is the response of the heart to a sudden decrease in blood pressure?

    <p>Increased heart rate</p> Signup and view all the answers

    What is the primary mechanism of action of vasodilators?

    <p>Producing relaxation of vascular smooth muscle</p> Signup and view all the answers

    Which of the following drugs is commonly used in the management of gestational hypertension and hypertensive emergencies?

    <p>Labetalol</p> Signup and view all the answers

    What is the primary use of methyldopa?

    <p>Treatment of hypertension in pregnancy</p> Signup and view all the answers

    Which of the following drugs is used topically to treat male pattern baldness?

    <p>Minoxidil</p> Signup and view all the answers

    What is the primary mechanism of action of clonidine?

    <p>Acting as an α2-agonist</p> Signup and view all the answers

    Which of the following β-blockers is often used in the management of heart failure?

    <p>Carvedilol</p> Signup and view all the answers

    What is a common side effect of methyldopa?

    <p>Sedation and drowsiness</p> Signup and view all the answers

    Which of the following drugs is almost always administered in combination with a β-blocker and a diuretic?

    <p>Hydralazine</p> Signup and view all the answers

    Study Notes

    Blood Pressure

    • Blood pressure is the pressure of blood against the inner walls of blood vessels, maintaining blood circulation even between heartbeats.
    • Two arterial blood pressure measurements are made: systolic pressure (peak ventricular contraction) and diastolic pressure (ventricular relaxation).

    Blood Pressure Measurement

    • Blood pressures are reported in millimeters of mercury (mm Hg), with systolic pressure written first (e.g., 120/80 mm Hg).

    Factors Affecting Blood Pressure

    • Cardiac output (CO) is the amount of blood pumped out of the left ventricle per minute, determined by stroke volume (SV) and heart rate (HR).
    • Peripheral resistance (PR) is the friction blood encounters in blood vessels, influenced by neural factors, renal factors, temperature, chemicals, and diet.
    • The hydraulic equation of blood pressure is: BP = CO x PR.
    • Many factors increase peripheral resistance, including neural factors, cold temperatures, and certain chemicals.

    Neural Factors

    • The autonomic nervous system plays a significant role in blood pressure regulation, with the sympathetic division causing vasoconstriction and increasing blood pressure.
    • Examples of neural factors affecting blood pressure include:
      • Standing up suddenly, which activates pressoreceptors and increases blood pressure.
      • Decreased blood volume, which triggers the heart to beat more rapidly and increases blood pressure.
      • Vigorous exercise or fright, which causes generalized vasoconstriction and increases blood pressure.

    Renal Factors

    • The kidneys regulate arterial blood pressure by altering blood volume.
    • When blood pressure increases, the kidneys allow more water to leave the body, decreasing blood volume and blood pressure.
    • Conversely, when blood pressure falls, the kidneys retain body water, increasing blood volume and blood pressure.
    • Renal factors also include the release of the enzyme renin, which triggers a series of chemical reactions leading to the formation of angiotensin II, a potent vasoconstrictor.

    Temperature

    • Cold temperatures have a vasoconstricting effect, increasing blood pressure.
    • Heat has a vasodilating effect, decreasing blood pressure.

    Chemicals

    • Various chemicals, including drugs, can affect blood pressure.
    • Examples include:
      • Epinephrine, which increases heart rate and blood pressure.
      • Nicotine, which increases blood pressure by causing vasoconstriction.
      • Alcohol and histamine, which decrease blood pressure by causing vasodilation.

    Diet

    • A diet low in salt, saturated fats, and cholesterol can help prevent hypertension.

    Mechanisms of Controlling Blood Pressure

    • Two overlapping control mechanisms regulate blood pressure: the baroreflex and the renin-angiotensin-aldosterone system (RAAS).
    • The baroreflex:
      • Acts by changing the activity of the sympathetic nervous system.
      • Responds to changes in blood pressure by sending signals to the heart and vasculature.
      • Regulates blood pressure through vasoconstriction and increased cardiac output.
    • The renin-angiotensin-aldosterone system (RAAS):
      • Responds to reduced arterial pressure and sympathetic stimulation.
      • Releases renin, which triggers a series of chemical reactions leading to the formation of angiotensin II.
      • Angiotensin II is a potent vasoconstrictor that increases blood pressure.

    Antihypertensive Drugs

    • Diuretics:
      • Lower blood pressure by depleting body sodium stores.
      • Classes of diuretics include thiazide, loop, and potassium-sparing diuretics.
      • Examples of diuretics include hydrochlorothiazide, furosemide, and spironolactone.
    • β-Adrenoreceptor blockers:
      • Reduce blood pressure by decreasing cardiac output.
      • May also decrease sympathetic outflow and inhibit renin release.
      • Examples of β-blockers include propranolol, metoprolol, and atenolol.
    • Angiotensin-converting enzyme (ACE) inhibitors:
      • Lower blood pressure by reducing peripheral vascular resistance.
      • Block the enzyme ACE, which cleaves angiotensin I to form angiotensin II.
      • Examples of ACE inhibitors include captopril, enalapril, and lisinopril.
    • Angiotensin II receptor blockers (ARBs):
      • Block the AT1 receptors, decreasing the activation of AT1 receptors by angiotensin II.
      • Examples of ARBs include losartan, valsartan, and candesartan.
    • Renin inhibitors:
      • Act earlier in the renin-angiotensin-aldosterone system than ACE inhibitors or ARBs.
      • Example of a renin inhibitor is aliskiren.
    • Calcium channel blockers:
      • Block the inward movement of calcium in the heart and smooth muscle.
      • Relax vascular smooth muscle, dilating arterioles.
      • Examples of calcium channel blockers include verapamil, diltiazem, and nifedipine.
    • α-Adrenoceptor blocking agents:
      • Produce a competitive block of α1-adrenoceptors.
      • Decrease peripheral vascular resistance and lower arterial blood pressure.
      • Examples of α-blockers include prazosin, doxazosin, and terazosin.
    • α-/β-Adrenoceptor blocking agents:
      • Block α1, β1, and β2 receptors.
      • Examples of α-/β-blockers include labetalol and carvedilol.
    • Centrally acting adrenergic drugs:
      • Act centrally as an α2-agonist to produce inhibition of sympathetic vasomotor centers.
      • Decrease sympathetic outflow to the periphery.
      • Examples of centrally acting adrenergic drugs include clonidine and methyldopa.
    • Vasodilators:
      • Act by producing relaxation of vascular smooth muscle, primarily in arteries and arterioles.
      • Decrease peripheral resistance and blood pressure.
      • Examples of vasodilators include hydralazine and minoxidil.

    Blood Pressure

    • Blood pressure is the pressure of blood against the inner walls of blood vessels, maintaining blood circulation even between heartbeats.
    • Two arterial blood pressure measurements are made: systolic pressure (peak ventricular contraction) and diastolic pressure (ventricular relaxation).

    Blood Pressure Measurement

    • Blood pressures are reported in millimeters of mercury (mm Hg), with systolic pressure written first (e.g., 120/80 mm Hg).

    Factors Affecting Blood Pressure

    • Cardiac output (CO) is the amount of blood pumped out of the left ventricle per minute, determined by stroke volume (SV) and heart rate (HR).
    • Peripheral resistance (PR) is the friction blood encounters in blood vessels, influenced by neural factors, renal factors, temperature, chemicals, and diet.
    • The hydraulic equation of blood pressure is: BP = CO x PR.
    • Many factors increase peripheral resistance, including neural factors, cold temperatures, and certain chemicals.

    Neural Factors

    • The autonomic nervous system plays a significant role in blood pressure regulation, with the sympathetic division causing vasoconstriction and increasing blood pressure.
    • Examples of neural factors affecting blood pressure include:
      • Standing up suddenly, which activates pressoreceptors and increases blood pressure.
      • Decreased blood volume, which triggers the heart to beat more rapidly and increases blood pressure.
      • Vigorous exercise or fright, which causes generalized vasoconstriction and increases blood pressure.

    Renal Factors

    • The kidneys regulate arterial blood pressure by altering blood volume.
    • When blood pressure increases, the kidneys allow more water to leave the body, decreasing blood volume and blood pressure.
    • Conversely, when blood pressure falls, the kidneys retain body water, increasing blood volume and blood pressure.
    • Renal factors also include the release of the enzyme renin, which triggers a series of chemical reactions leading to the formation of angiotensin II, a potent vasoconstrictor.

    Temperature

    • Cold temperatures have a vasoconstricting effect, increasing blood pressure.
    • Heat has a vasodilating effect, decreasing blood pressure.

    Chemicals

    • Various chemicals, including drugs, can affect blood pressure.
    • Examples include:
      • Epinephrine, which increases heart rate and blood pressure.
      • Nicotine, which increases blood pressure by causing vasoconstriction.
      • Alcohol and histamine, which decrease blood pressure by causing vasodilation.

    Diet

    • A diet low in salt, saturated fats, and cholesterol can help prevent hypertension.

    Mechanisms of Controlling Blood Pressure

    • Two overlapping control mechanisms regulate blood pressure: the baroreflex and the renin-angiotensin-aldosterone system (RAAS).
    • The baroreflex:
      • Acts by changing the activity of the sympathetic nervous system.
      • Responds to changes in blood pressure by sending signals to the heart and vasculature.
      • Regulates blood pressure through vasoconstriction and increased cardiac output.
    • The renin-angiotensin-aldosterone system (RAAS):
      • Responds to reduced arterial pressure and sympathetic stimulation.
      • Releases renin, which triggers a series of chemical reactions leading to the formation of angiotensin II.
      • Angiotensin II is a potent vasoconstrictor that increases blood pressure.

    Antihypertensive Drugs

    • Diuretics:
      • Lower blood pressure by depleting body sodium stores.
      • Classes of diuretics include thiazide, loop, and potassium-sparing diuretics.
      • Examples of diuretics include hydrochlorothiazide, furosemide, and spironolactone.
    • β-Adrenoreceptor blockers:
      • Reduce blood pressure by decreasing cardiac output.
      • May also decrease sympathetic outflow and inhibit renin release.
      • Examples of β-blockers include propranolol, metoprolol, and atenolol.
    • Angiotensin-converting enzyme (ACE) inhibitors:
      • Lower blood pressure by reducing peripheral vascular resistance.
      • Block the enzyme ACE, which cleaves angiotensin I to form angiotensin II.
      • Examples of ACE inhibitors include captopril, enalapril, and lisinopril.
    • Angiotensin II receptor blockers (ARBs):
      • Block the AT1 receptors, decreasing the activation of AT1 receptors by angiotensin II.
      • Examples of ARBs include losartan, valsartan, and candesartan.
    • Renin inhibitors:
      • Act earlier in the renin-angiotensin-aldosterone system than ACE inhibitors or ARBs.
      • Example of a renin inhibitor is aliskiren.
    • Calcium channel blockers:
      • Block the inward movement of calcium in the heart and smooth muscle.
      • Relax vascular smooth muscle, dilating arterioles.
      • Examples of calcium channel blockers include verapamil, diltiazem, and nifedipine.
    • α-Adrenoceptor blocking agents:
      • Produce a competitive block of α1-adrenoceptors.
      • Decrease peripheral vascular resistance and lower arterial blood pressure.
      • Examples of α-blockers include prazosin, doxazosin, and terazosin.
    • α-/β-Adrenoceptor blocking agents:
      • Block α1, β1, and β2 receptors.
      • Examples of α-/β-blockers include labetalol and carvedilol.
    • Centrally acting adrenergic drugs:
      • Act centrally as an α2-agonist to produce inhibition of sympathetic vasomotor centers.
      • Decrease sympathetic outflow to the periphery.
      • Examples of centrally acting adrenergic drugs include clonidine and methyldopa.
    • Vasodilators:
      • Act by producing relaxation of vascular smooth muscle, primarily in arteries and arterioles.
      • Decrease peripheral resistance and blood pressure.
      • Examples of vasodilators include hydralazine and minoxidil.

    Blood Pressure

    • Blood pressure is the pressure of blood against the inner walls of blood vessels, maintaining blood circulation even between heartbeats.
    • Two arterial blood pressure measurements are made: systolic pressure (peak ventricular contraction) and diastolic pressure (ventricular relaxation).

    Blood Pressure Measurement

    • Blood pressures are reported in millimeters of mercury (mm Hg), with systolic pressure written first (e.g., 120/80 mm Hg).

    Factors Affecting Blood Pressure

    • Cardiac output (CO) is the amount of blood pumped out of the left ventricle per minute, determined by stroke volume (SV) and heart rate (HR).
    • Peripheral resistance (PR) is the friction blood encounters in blood vessels, influenced by neural factors, renal factors, temperature, chemicals, and diet.
    • The hydraulic equation of blood pressure is: BP = CO x PR.
    • Many factors increase peripheral resistance, including neural factors, cold temperatures, and certain chemicals.

    Neural Factors

    • The autonomic nervous system plays a significant role in blood pressure regulation, with the sympathetic division causing vasoconstriction and increasing blood pressure.
    • Examples of neural factors affecting blood pressure include:
      • Standing up suddenly, which activates pressoreceptors and increases blood pressure.
      • Decreased blood volume, which triggers the heart to beat more rapidly and increases blood pressure.
      • Vigorous exercise or fright, which causes generalized vasoconstriction and increases blood pressure.

    Renal Factors

    • The kidneys regulate arterial blood pressure by altering blood volume.
    • When blood pressure increases, the kidneys allow more water to leave the body, decreasing blood volume and blood pressure.
    • Conversely, when blood pressure falls, the kidneys retain body water, increasing blood volume and blood pressure.
    • Renal factors also include the release of the enzyme renin, which triggers a series of chemical reactions leading to the formation of angiotensin II, a potent vasoconstrictor.

    Temperature

    • Cold temperatures have a vasoconstricting effect, increasing blood pressure.
    • Heat has a vasodilating effect, decreasing blood pressure.

    Chemicals

    • Various chemicals, including drugs, can affect blood pressure.
    • Examples include:
      • Epinephrine, which increases heart rate and blood pressure.
      • Nicotine, which increases blood pressure by causing vasoconstriction.
      • Alcohol and histamine, which decrease blood pressure by causing vasodilation.

    Diet

    • A diet low in salt, saturated fats, and cholesterol can help prevent hypertension.

    Mechanisms of Controlling Blood Pressure

    • Two overlapping control mechanisms regulate blood pressure: the baroreflex and the renin-angiotensin-aldosterone system (RAAS).
    • The baroreflex:
      • Acts by changing the activity of the sympathetic nervous system.
      • Responds to changes in blood pressure by sending signals to the heart and vasculature.
      • Regulates blood pressure through vasoconstriction and increased cardiac output.
    • The renin-angiotensin-aldosterone system (RAAS):
      • Responds to reduced arterial pressure and sympathetic stimulation.
      • Releases renin, which triggers a series of chemical reactions leading to the formation of angiotensin II.
      • Angiotensin II is a potent vasoconstrictor that increases blood pressure.

    Antihypertensive Drugs

    • Diuretics:
      • Lower blood pressure by depleting body sodium stores.
      • Classes of diuretics include thiazide, loop, and potassium-sparing diuretics.
      • Examples of diuretics include hydrochlorothiazide, furosemide, and spironolactone.
    • β-Adrenoreceptor blockers:
      • Reduce blood pressure by decreasing cardiac output.
      • May also decrease sympathetic outflow and inhibit renin release.
      • Examples of β-blockers include propranolol, metoprolol, and atenolol.
    • Angiotensin-converting enzyme (ACE) inhibitors:
      • Lower blood pressure by reducing peripheral vascular resistance.
      • Block the enzyme ACE, which cleaves angiotensin I to form angiotensin II.
      • Examples of ACE inhibitors include captopril, enalapril, and lisinopril.
    • Angiotensin II receptor blockers (ARBs):
      • Block the AT1 receptors, decreasing the activation of AT1 receptors by angiotensin II.
      • Examples of ARBs include losartan, valsartan, and candesartan.
    • Renin inhibitors:
      • Act earlier in the renin-angiotensin-aldosterone system than ACE inhibitors or ARBs.
      • Example of a renin inhibitor is aliskiren.
    • Calcium channel blockers:
      • Block the inward movement of calcium in the heart and smooth muscle.
      • Relax vascular smooth muscle, dilating arterioles.
      • Examples of calcium channel blockers include verapamil, diltiazem, and nifedipine.
    • α-Adrenoceptor blocking agents:
      • Produce a competitive block of α1-adrenoceptors.
      • Decrease peripheral vascular resistance and lower arterial blood pressure.
      • Examples of α-blockers include prazosin, doxazosin, and terazosin.
    • α-/β-Adrenoceptor blocking agents:
      • Block α1, β1, and β2 receptors.
      • Examples of α-/β-blockers include labetalol and carvedilol.
    • Centrally acting adrenergic drugs:
      • Act centrally as an α2-agonist to produce inhibition of sympathetic vasomotor centers.
      • Decrease sympathetic outflow to the periphery.
      • Examples of centrally acting adrenergic drugs include clonidine and methyldopa.
    • Vasodilators:
      • Act by producing relaxation of vascular smooth muscle, primarily in arteries and arterioles.
      • Decrease peripheral resistance and blood pressure.
      • Examples of vasodilators include hydralazine and minoxidil.

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    Description

    Learn about blood pressure, its definition, and the two types of arterial blood pressure measurements: systolic and diastolic pressure.

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