Katzung - Chapter 11

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Questions and Answers

What is the syndrome characterized by arthralgia, myalgia, skin rashes, and fever associated with high doses of certain drugs?

Lupus erythematosus syndrome (correct)

Vasculitis syndrome

Stevens-Johnson syndrome

Dermatitis syndrome

How does minoxidil primarily exert its vasodilatory effect?

By inhibiting calcium influx

By opening potassium channels (correct)

By blocking sodium channels

By activating beta receptors

What effect does vasopressin have on blood pressure?

Regulates water reabsorption (correct)

Increases heart rate

Inhibits sympathetic activity

Decreases venous return

Which of the following is a serious but uncommon adverse effect of certain vasodilators?

Peripheral neuropathy Signup and view all the answers

Why is hydralazine considered less effective at high doses compared to minoxidil?

Because of its lower antihypertensive effect Signup and view all the answers

How do carotid baroreceptors respond to increased arterial blood pressure?

They inhibit central sympathetic discharge Signup and view all the answers

What is one of the pathways by which smooth muscle cells become hyperpolarized?

Opening of potassium channels Signup and view all the answers

What physiological change occurs when a person transitions from a reclining to an upright posture?

Reduction in arterial pressure Signup and view all the answers

What type of blood vessels does minoxidil primarily affect?

Arterioles only Signup and view all the answers

Which category of antihypertensive agents acts by depleting sodium and reducing blood volume?

Diuretics Signup and view all the answers

What is the role of central sympathetic neurons originating from the vasomotor area of the medulla?

They are tonically active Signup and view all the answers

What happens to sympathetic outflow when baroreceptor activity decreases?

Sympathetic discharge increases Signup and view all the answers

What effect do antihypertensive agents typically have on blood pressure regulation?

They interfere with normal blood pressure regulation Signup and view all the answers

What is the primary role of the baroreflex in response to low arterial pressure?

Increases sympathetic outflow Signup and view all the answers

What occurs when there is a primary reduction in peripheral vascular resistance?

Sympathetic discharge is inhibited Signup and view all the answers

What percentage of patients may experience inadequate response to treatment in managing hypertension?

40% Signup and view all the answers

What is one common reason for using multiple drugs in treating hypertension?

To utilize compensatory regulatory mechanisms Signup and view all the answers

Which drug can evoke a strong compensatory tachycardia when used to manage hypertension?

Hydralazine Signup and view all the answers

Why might a β blocker be added to a regimen including hydralazine?

To prevent tachycardia Signup and view all the answers

What is a potential outcome of using three or more drugs for managing hypertension?

Improved sensitivity of the cardiovascular system Signup and view all the answers

What should be done if the response to two drugs in patients is still inadequate?

Add a third drug from a different class Signup and view all the answers

Which of the following is stated to be particularly indicated for patients with a myocardial infarction and hypertension?

β blockers Signup and view all the answers

What can dietary sodium restriction help with in the context of hypertension treatment?

Enhance the effects of diuretics Signup and view all the answers

What is one limitation noted regarding the use of certain β blockers?

Variability in effectiveness amongst the group Signup and view all the answers

What is the primary mechanism by which diuretics lower blood pressure?

Depleting body sodium stores Signup and view all the answers

What effect does a diuretic like hydrochlorothiazide have when combined with other antihypertensive medications?

Prevents salt and water retention Signup and view all the answers

What happens to peripheral vascular resistance after 6-8 weeks of diuretic use?

It decreases Signup and view all the answers

Which type of diuretic is suitable for patients with mild to moderate hypertension?

Thiazide diuretics Signup and view all the answers

When are more powerful diuretics, such as furosemide, necessary?

In severe hypertension Signup and view all the answers

In which condition are diuretics typically used in combination with other drugs?

Cirrhosis Signup and view all the answers

What is a common effect of sodium on vascular resistance?

Increases vessel stiffness Signup and view all the answers

Why are potassium-sparing diuretics used?

To avoid potassium depletion Signup and view all the answers

What is the effect of diuretics on blood pressure in most patients?

It lowers blood pressure by 10-15 mm Hg Signup and view all the answers

What condition might indicate the use of diuretics when the glomerular filtration rate is low?

Severe hypertension Signup and view all the answers

How do sympathoplegic drugs affect vascular responsiveness?

They diminish the ability to constrict or dilate Signup and view all the answers

What is the usual oral dose of methyldopa expected to achieve its maximal antihypertensive effect?

4-6 hours Signup and view all the answers

Which neurotransmitter's release is reduced by clonidine and α-methylnorepinephrine in the brain?

Norepinephrine Signup and view all the answers

What is the most common undesirable effect of methyldopa?

Sedation Signup and view all the answers

How does clonidine primarily exert its hypotensive effect?

By acting on α adrenoceptors in the medulla Signup and view all the answers

What may be accompanied by the reduction in blood pressure when using clonidine?

Bradycardia Signup and view all the answers

Long-term therapy with methyldopa may lead to which of the following complaints?

Mental lassitude Signup and view all the answers

What possible toxic effect can occur both in men and women treated with methyldopa?

Lactation Signup and view all the answers

Which mechanism might be responsible for the toxic effects of clonidine and α-methylnorepinephrine?

Inhibition of dopaminergic mechanisms Signup and view all the answers

What type of receptors bind more tightly to clonidine and α-methylnorepinephrine?

α2 adrenoceptors Signup and view all the answers

What role do central adrenergic neurons play in blood pressure regulation?

They modulate baroreceptor reflexes Signup and view all the answers

Study Notes

Blood Pressure Regulation Mechanisms

Vasopressin from the posterior pituitary helps maintain blood pressure through kidney water reabsorption.
Central sympathetic neurons are constantly active, influencing blood pressure regulation.
Carotid baroreceptors detect arterial pressure through vessel wall stretch; their activation inhibits sympathetic discharge.
Transitioning to an upright posture activates baroreceptors, which sense decreased arterial pressure from blood pooling.

Antihypertensive Agents

Antihypertensive drugs function at four main anatomical control sites and disrupt normal blood pressure regulation.
Diuretics reduce blood pressure by depleting sodium and lowering blood volume. They are effective in mild to moderate hypertension.
Some patients experience "resistant hypertension," requiring three or more drugs due to compensatory mechanisms that limit drug efficacy.

Drug Classes & Effects

β-blockers exhibit varying efficacy; metoprolol and carvedilol are generally preferred for their benefits compared to atenolol.
Polypharmacy is employed due to compensatory responses that can diminish individual drug effectiveness.
Diuretics coupled with β-blockers and vasodilators enhance overall treatment by countering side effects such as tachycardia and sodium retention.

Diuretic Mechanisms

Initial reduction in blood pressure is due to decreased blood volume and cardiac output, with subsequent normalization of cardiac output over weeks.
Sodium is linked to vascular resistance through increased vessel stiffness; diuretics or sodium restriction can reverse these effects.

Clonidine and Methyldopa

Clonidine lowers blood pressure by acting on α adrenoceptors in the medulla, enhancing parasympathetic tone.
Long-term use of methyldopa can lead to sedation, mental fatigue, and elevated prolactin, affecting both genders.

Side Effects & Adverse Reactions

Methyldopa commonly causes sedation; serious effects like peripheral neuropathy can occur with certain dosages.
Hyperpolarization of smooth muscle membranes can be induced by specific vasodilators like minoxidil.
Both minoxidil and hydralazine primarily affect arterioles, influencing their use in severe hypertension.

Conclusion

Effective management of hypertension often necessitates a combination of drugs from different classes for optimal control and to mitigate adverse effects.

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Description

This quiz covers the mechanisms involved in blood pressure regulation, focusing on the roles of vasopressin and the autonomic nervous system. It also examines how the body responds to changes in posture and the function of baroreceptors. Prepare to test your knowledge on these vital physiological processes.