Calcium Channel Blockers

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  • 1/54 Questions

    Calcium channel blockers exhibit a mechanism of action in both cardiac cells and vascular muscle cells.

    • True
    • False
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About This Quiz

Explore the role of calcium channel blockers in medical treatment through this quiz. Assess knowledge on their classification, applications in disease management like hypertension and angina, and understanding of their mechanism. Essential for students and professionals in medicine and pharmacology.

Calcium Channel Blockers - Quiz

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  • 2. 

    Through their mechanisms, calcium channel blockers work in angina because they reduce the oxygen demand (through decreasing resistance), as well as increase the oxygen supply (through relaxation of the arteries).

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channel blockers are medications that work by blocking the calcium channels in the smooth muscle cells of the arteries. By doing so, they cause relaxation of the arteries, leading to vasodilation. This vasodilation reduces the resistance in the arteries, allowing for better blood flow and decreasing the workload on the heart. As a result, the oxygen demand of the heart is reduced. Additionally, the relaxation of the arteries also improves the oxygen supply to the heart. Therefore, it is true that calcium channel blockers work in angina by reducing the oxygen demand and increasing the oxygen supply.

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  • 3. 

    The most common side effects of calcium channel blockers, dizziness, hypotension, headache, and facial flushing, can be attributed to which of the following?

    • Excessive vasodilation

    • Excessive vasoconstriction

    Correct Answer
    A. Excessive vasodilation
    Explanation
    The most common side effects of calcium channel blockers, such as dizziness, hypotension, headache, and facial flushing, can be attributed to excessive vasodilation. Calcium channel blockers work by blocking the entry of calcium into smooth muscle cells, which causes relaxation and widening of blood vessels. This leads to a decrease in blood pressure and increased blood flow. However, excessive vasodilation can result in symptoms like dizziness, low blood pressure, headache, and flushing.

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  • 4. 

    Because L type calcium channels are enriched in the cardiac and smooth muscle, SA node, and Purkinje cells, they play an important role in __________.

    • Contration, heart rate, and conduction

    • Neurotransmitter release

    Correct Answer
    A. Contration, heart rate, and conduction
    Explanation
    L type calcium channels are present in cardiac and smooth muscle cells, as well as in the SA node and Purkinje cells. These channels are responsible for regulating the influx of calcium ions into these cells. Calcium ions are crucial for muscle contraction, therefore L type calcium channels play a significant role in controlling contraction in the heart and smooth muscles. Additionally, they also contribute to regulating heart rate and conduction of electrical signals in the heart.

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  • 5. 

    Calcium channel blockers can be used as anti-anginal drugs.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channel blockers are a class of medications that work by blocking calcium channels in the heart and blood vessels, leading to relaxation of the smooth muscles and dilation of the blood vessels. This results in improved blood flow and reduced oxygen demand by the heart, making them effective in relieving angina symptoms. Therefore, calcium channel blockers can indeed be used as anti-anginal drugs, supporting the statement that the answer is true.

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  • 6. 

    Calcium channel blockers can be used in treating essential hypertension because of their prominent vascular effects.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channel blockers are a class of medications that work by blocking the entry of calcium into the muscle cells of blood vessels. This causes the blood vessels to relax and widen, resulting in decreased resistance to blood flow and lower blood pressure. Therefore, calcium channel blockers are effective in treating essential hypertension, which is characterized by high blood pressure with no identifiable cause. Their prominent vascular effects make them a suitable option for managing this condition.

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  • 7. 

    In vasospastic angina, calcium channel blockers primarily increase oxygen supply through coronary artery dilation to prevent vasospasms.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    In vasospastic angina, the blood vessels in the coronary arteries can constrict or spasm, leading to reduced blood flow and oxygen supply to the heart. Calcium channel blockers are medications that can relax and dilate the blood vessels, including the coronary arteries. By doing so, they increase the blood flow and oxygen supply to the heart, preventing or relieving vasospasms and reducing the symptoms of vasospastic angina. Therefore, the statement is true.

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  • 8. 

    In cardiac muscle cells, which of the following occurs due to calcium channel blockers preventing calcium's entry into the cell?

    • Relaxation

    • Contraction

    Correct Answer
    A. Relaxation
    Explanation
    Calcium channel blockers prevent calcium from entering cardiac muscle cells. Calcium is required for muscle contraction, so when its entry is blocked, the muscle cells are unable to contract effectively. As a result, the muscle cells relax, leading to relaxation of the cardiac muscle.

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  • 9. 

    Calcium channel blockers have a much more prominent effect in decreasing vascular smooth muscle contraction in arteries.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channel blockers are medications that work by blocking the entry of calcium into smooth muscle cells, causing them to relax. Arteries have a higher concentration of smooth muscle compared to veins, which makes them more responsive to the effects of calcium channel blockers. Therefore, calcium channel blockers have a much more prominent effect in decreasing vascular smooth muscle contraction in arteries compared to other blood vessels.

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  • 10. 

    In stable exertional angina, calcium channel blockers are able to increase oxygen supply, as well as decrease oxygen demand.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channel blockers are commonly used in the treatment of stable exertional angina. These medications work by relaxing and widening the blood vessels, which improves blood flow to the heart and increases oxygen supply. Additionally, calcium channel blockers can also reduce the workload on the heart by decreasing the force of contraction and heart rate, thus decreasing oxygen demand. Therefore, it is true that calcium channel blockers are able to increase oxygen supply and decrease oxygen demand in stable exertional angina.

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  • 11. 

    Which of the following occurs because calcium entry into vascular smooth muscle is blocked by calcium channel blockers?

    • Contraction

    • Relaxation

    Correct Answer
    A. Relaxation
    Explanation
    Calcium channel blockers work by blocking the entry of calcium into vascular smooth muscle. Calcium is necessary for muscle contraction, so when calcium entry is blocked, it prevents the muscle from contracting. Therefore, the correct answer is relaxation.

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  • 12. 

    Because verapamil and diltiazem are able to decrease the rate of recovery of L calcium channels, this has which of the following effects on heart rate and conduction?

    • Decreased heart rate, decreased conduction

    • Increased heart rate, increased conduction

    • Verapamil and diltiazem are not able to decrease the rate of recovery

    Correct Answer
    A. Decreased heart rate, decreased conduction
    Explanation
    Verapamil and diltiazem are calcium channel blockers that work by decreasing the rate of recovery of L-type calcium channels. L-type calcium channels play a role in the initiation and conduction of electrical signals in the heart. By slowing down the recovery of these channels, verapamil and diltiazem reduce the influx of calcium ions into cardiac cells, leading to decreased heart rate and decreased conduction of electrical signals through the heart. This ultimately results in a slower heart rate and a decrease in the conduction of electrical impulses in the heart.

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  • 13. 

    Calcium is responsible for the __________ of muscle.

    Correct Answer
    contraction
    Explanation
    Calcium plays a crucial role in muscle contraction. When a muscle receives a signal to contract, calcium ions are released from storage sites within the muscle cells. These calcium ions bind to proteins within the muscle fibers, causing them to slide past each other. This sliding action shortens the length of the muscle fibers, resulting in muscle contraction. Therefore, calcium is responsible for the contraction of muscle.

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  • 14. 

    Calcium channel blockers can be divided into three class based on their chemical structure. Which of the following is not a class of calcium channel blockers?

    • Nitrates

    • Penylalkylamines

    • Dihydropyridines

    • Benzothiazepines

    Correct Answer
    A. Nitrates
    Explanation
    Nitrates are not a class of calcium channel blockers. Calcium channel blockers are divided into three classes based on their chemical structure: penylalkylamines, dihydropyridines, and benzothiazepines. Nitrates, on the other hand, are a different class of drugs used primarily for the treatment of angina and heart failure. They work by dilating blood vessels and reducing the workload on the heart. While both calcium channel blockers and nitrates can be used to treat certain cardiovascular conditions, they have different mechanisms of action and chemical structures.

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  • 15. 

    Which of the following are classified as "dihydropyridines" of the calcium channel blockers?

    • Nicardipine

    • Amlodipine

    • Diltiazem

    • Nifedipine

    • Verapamil

    • Felodipine

    Correct Answer(s)
    A. Nicardipine
    A. Amlodipine
    A. Nifedipine
    A. Felodipine
    Explanation
    -PINES are dihydropyridine calcium channel blockers

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  • 16. 

    Calcium enters excitable cells via potential or voltage-dependent calcium channels, which are similar to other ion channels.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium enters excitable cells through potential or voltage-dependent calcium channels, which operate similarly to other ion channels. These channels open and close in response to changes in the cell's membrane potential, allowing calcium ions to flow into the cell. This influx of calcium plays a crucial role in various cellular processes, including muscle contraction, neurotransmitter release, and gene expression. Therefore, the statement that calcium enters excitable cells via potential or voltage-dependent calcium channels is true.

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  • 17. 

    Which of the following is NOT a type of calcium channel?

    • L

    • S

    • N

    • T

    Correct Answer
    A. S
    Explanation
    The correct answer is S. The question asks for a type of calcium channel that does not exist. The options provided include L, S, N, and T. L, N, and T are all types of calcium channels, but S is not. Therefore, S is the correct answer as it is not a type of calcium channel.

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  • 18. 

    Which of the following drugs has a side effect of tachycardia?

    • Diltiazem

    • Nifedipine

    • Verapamil

    Correct Answer
    A. Nifedipine
    Explanation
    Nifedipine is a calcium channel blocker commonly used to treat high blood pressure and angina. One of its known side effects is tachycardia, which refers to an abnormally fast heart rate. This occurs because nifedipine relaxes the smooth muscles in the blood vessels, leading to a drop in blood pressure. In response, the body may compensate by increasing the heart rate to maintain adequate blood flow. Therefore, it is important to monitor patients taking nifedipine for any signs of tachycardia and adjust the dosage accordingly.

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  • 19. 

    Which type of calcium channel do the calcium channel blockers selectively inhibit?

    • N

    • T

    • L

    Correct Answer
    A. L
    Explanation
    Calcium channel blockers selectively inhibit L-type calcium channels. These channels are found in various tissues, including smooth muscle cells of the cardiovascular system. By blocking these channels, calcium channel blockers reduce the influx of calcium ions into the cells, leading to relaxation of smooth muscles and vasodilation. This mechanism of action is particularly useful in treating conditions such as hypertension, angina, and certain arrhythmias.

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  • 20. 

    Depending on the class of calcium channel blocker, these drugs can have direct negative chronotropic (heart rate) and dromotropic (conduction) effects, too. Which class does not show these additional effects?

    • Dihydropyridines (Nifedipine)

    • Phenylalkylamines (Verapamil)

    • Benzothiazepines (Diltiazem)

    Correct Answer
    A. Dihydropyridines (Nifedipine)
    Explanation
    Dihydropyridines (Nifedipine) do not show direct negative chronotropic (heart rate) and dromotropic (conduction) effects.

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  • 21. 

    T type calcium channels were once a target for anti-anginal drugs as they are located in the SA node and Purkinje cells, playing a role in pacemaker activity and conduction, but the ones developed were found to be toxic. It is still a possible area for development of anti-anginals.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    T type calcium channels were once a target for anti-anginal drugs because they are found in the SA node and Purkinje cells, which are involved in pacemaker activity and conduction. However, the drugs developed to target these channels were found to be toxic. Despite this setback, the development of anti-anginals targeting T type calcium channels remains a possibility.

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  • 22. 

    Calcium channels are sometimes called slow channels because of their delayed response in the cardiac action potential.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Calcium channels are indeed sometimes referred to as slow channels because they have a delayed response in the cardiac action potential. This delay occurs because calcium channels open relatively slowly compared to other ion channels involved in the action potential. Calcium influx through these channels plays a crucial role in various physiological processes, including muscle contraction and neurotransmitter release. Therefore, the delayed response of calcium channels contributes to the overall timing and coordination of cardiac activity.

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  • 23. 

    Calcium channel blockers can be used in which of the following conditions?

    • Vasospastic angina

    • Stable exertional angina

    • Essential hypertension

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Calcium channel blockers can be used in the treatment of vasospastic angina, stable exertional angina, and essential hypertension. These medications work by blocking calcium channels in the smooth muscle cells of blood vessels, causing them to relax and dilate. This helps to improve blood flow and reduce the workload on the heart. Therefore, calcium channel blockers are effective in treating these conditions.

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  • 24. 

    Calcium channel blockers allow calcium movement from outside the cell to inside the cell through their channels.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    prevent movement

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  • 25. 

    Calcium channel blockers have a large effect on the veins, as well as the cardiac preload.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Calcium channel blockers have little or no effect on the veins and no effect on cardiac preload.

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  • 26. 

    In addition to angina, calcium channel blockers can be used therapeutically in the treatment of which of the following diseases?

    • Essential hypertension

    • Cardiac arrhythmias

    • Type II Diabetes

    Correct Answer(s)
    A. Essential hypertension
    A. Cardiac arrhythmias
    Explanation
    Calcium channel blockers are a class of medications that work by blocking the entry of calcium into smooth muscle cells, which leads to relaxation of the blood vessels and a decrease in blood pressure. Therefore, they are commonly used in the treatment of essential hypertension, which is characterized by high blood pressure. Additionally, calcium channel blockers can also be used to treat cardiac arrhythmias, as they can help regulate the heart's rhythm. However, they are not typically used in the treatment of Type II Diabetes, as their primary mechanism of action is not directly related to blood sugar control.

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  • 27. 

    The relaxation produced in coronary and peripheral vascular smooth muscle decreases peripheral resistance, which results in which of the following?

    • Decrease pressure and decreased cardiac preload

    • Increased pressure and increase cardiac preload

    • Decreased pressure and decreased cardiac afterload

    Correct Answer
    A. Decreased pressure and decreased cardiac afterload
    Explanation
    The relaxation of coronary and peripheral vascular smooth muscle leads to a decrease in peripheral resistance. This decrease in resistance causes a decrease in pressure, as the blood flow encounters less resistance while moving through the blood vessels. Additionally, the decreased peripheral resistance also leads to a decrease in cardiac afterload, which is the amount of resistance the heart has to overcome to pump blood out of the left ventricle. Therefore, the correct answer is "Decreased pressure and decreased cardiac afterload."

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  • 28. 

    Because calcium channels are responsible for the plateau phase, which of the following occur when calcium channel blockers are used?

    • More calcium enters the cell

    • Negative inotropic effect

    • Less calcium enters the cell

    • Positive inotropic effect

    • Decrease in contractility

    • Increase in contractility

    Correct Answer(s)
    A. Negative inotropic effect
    A. Less calcium enters the cell
    A. Decrease in contractility
    Explanation
    When calcium channel blockers are used, they block the calcium channels on the cell membrane. This results in less calcium entering the cell during the plateau phase of cardiac action potential. The decrease in calcium entry leads to a negative inotropic effect, which means it reduces the force of contraction of the heart. This decrease in contractility is due to the reduced availability of calcium, which is essential for muscle contraction. Therefore, the correct answer is "Negative inotropic effect, Less calcium enters the cell, Decrease in contractility."

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  • 29. 

    Which of the following drugs has the side effects of AV block and worsening of heart failure?

    • Nifedipine

    • Diltiazem

    • Verapamil

    Correct Answer
    A. Verapamil
    Explanation
    Verapamil is known to have the side effects of AV block and worsening of heart failure. AV block refers to a condition where there is a disruption in the electrical signals between the upper and lower chambers of the heart, leading to a slower heart rate. Verapamil is a calcium channel blocker that can cause AV block as a side effect. Additionally, it can also worsen heart failure, a condition in which the heart is unable to pump blood effectively. Therefore, Verapamil is the correct answer in this case.

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  • 30. 

    Which of the following drugs can be dangerous in a patient with congestive heart failure?

    • Nifedipine

    • Verapamil

    • Diltiazem

    Correct Answer
    A. Verapamil
    Explanation
    Verapamil can be dangerous in a patient with congestive heart failure because it is a calcium channel blocker that can lower blood pressure and slow down the heart rate. In congestive heart failure, the heart is already weakened and struggling to pump blood effectively. Verapamil's effects can further impair the heart's ability to pump, worsening the symptoms of congestive heart failure and potentially leading to complications. Therefore, caution should be exercised when prescribing Verapamil to patients with congestive heart failure.

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  • 31. 

    Normally, without calcium, troponin C does which of the following in cardiac muscle cells?

    • Inhibits myosin and actin's interactions to produce contraction

    • Allows myosin and actin's interactions to produce contraction to occur uninhibited

    Correct Answer
    A. Inhibits myosin and actin's interactions to produce contraction
    Explanation
    Troponin C is a protein that plays a crucial role in muscle contraction. In cardiac muscle cells, without calcium, troponin C inhibits the interactions between myosin and actin. This means that the muscle contraction process is prevented from occurring, as the binding of myosin to actin is necessary for contraction to happen. Therefore, the correct answer is that without calcium, troponin C inhibits myosin and actin's interactions to produce contraction.

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  • 32. 

    The influx of calcium is responsible for maintaining which phase of the action potential? (Can answer with either # or word)

    Correct Answer
    2
    Plateau
    Explanation
    The correct answer is "Plateau". During the action potential, there are different phases including depolarization, repolarization, and hyperpolarization. The influx of calcium ions plays a crucial role in the plateau phase of the action potential. This phase is characterized by a sustained depolarization of the cell membrane, which is mainly due to the influx of calcium ions. The plateau phase helps in prolonging the action potential and is important for certain physiological processes like muscle contraction and cardiac function.

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  • 33. 

    Calcium entry is responsible for which phase in the action potential?

    • Phase 0

    • Phase 1

    • Phase 2

    Correct Answer
    A. Phase 2
    Explanation
    Calcium entry is responsible for Phase 2 in the action potential. During Phase 2, calcium ions enter the cell, leading to the plateau phase of the action potential. This influx of calcium ions helps to sustain depolarization and prolong the action potential, allowing for proper contraction and relaxation of cardiac muscle cells.

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  • 34. 

    Verapamil and diltiazem are use dependent, which makes them especially effective in bradycardias.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Verapamil and diltiazem are not use dependent, which means their effectiveness is not influenced by the heart rate. They are actually more commonly used to treat tachycardias rather than bradycardias. Therefore, the given statement is incorrect.

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  • 35. 

    In ventricular dysfunction or SA/AV node conduction disturbances, patients should not be treated with which of the following drugs intravenously, due to the risk of hypotension and bradycardia?

    • Verapamil IV

    • Diltiazem IV

    • Nifedipine IV

    • A and B

    • B and C

    • A and C

    • A, B, and C

    Correct Answer
    A. A and B
    Explanation
    Verapamil IV and Diltiazem IV should not be administered intravenously in patients with ventricular dysfunction or SA/AV node conduction disturbances due to the risk of hypotension and bradycardia. These drugs are calcium channel blockers that can cause a decrease in blood pressure and heart rate, which can be dangerous in patients with compromised cardiac function. Nifedipine IV does not have the same risk profile and can be used in these patients. Therefore, the correct answer is A and B.

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  • 36. 

    Verapamil and diltiazem are sometimes called "use dependant" for which reason?

    • Their effectiveness is dependent on the frequency of use of the drugs

    • Their effectiveness is dependent on the frequency of use of the channels

    Correct Answer
    A. Their effectiveness is dependent on the frequency of use of the channels
    Explanation
    More effective if the channels are frequently opening and closing - the more the channel is used, the more it opens and closes!

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  • 37. 

    Which state of the calcium channel do the calcium channel blockers that are able to decrease the rate of recovery of the channel preferentially bind to?

    • Resting

    • Inactivated

    • Activated

    Correct Answer
    A. Inactivated
    Explanation
    Calcium channel blockers that decrease the rate of recovery of the channel preferentially bind to the inactivated state of the calcium channel. This is because during the inactivated state, the channel is closed and unable to conduct calcium ions. By binding to the inactivated state, the calcium channel blockers prevent the channel from reopening and inhibit the influx of calcium ions into the cell. This ultimately leads to a decrease in the rate of recovery of the channel and a reduction in calcium-dependent cellular processes.

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  • 38. 

    How is the process for contraction in cardiac muscle different than in vascular smooth muscle?

    • Cardiac muscle cells use calcium to bind troponin C

    • Vascular smooth muscle cells use calcium to bind troponin C

    • Cardiac muscle cells use calcium to bind calmodulin

    • Vascular smooth muscle cells use calcium to bind calmodulin

    Correct Answer(s)
    A. Cardiac muscle cells use calcium to bind troponin C
    A. Vascular smooth muscle cells use calcium to bind calmodulin
    Explanation
    In cardiac muscle cells, the process of contraction involves the binding of calcium to troponin C. Troponin C is a regulatory protein that, when bound to calcium, causes a conformational change in the troponin-tropomyosin complex, allowing myosin to bind to actin and initiate muscle contraction. On the other hand, in vascular smooth muscle cells, the process of contraction involves the binding of calcium to calmodulin. Calmodulin is a calcium-binding protein that, when bound to calcium, activates myosin light chain kinase, leading to phosphorylation of myosin and initiation of muscle contraction. Therefore, the process of contraction in cardiac muscle and vascular smooth muscle differs in terms of the proteins involved in calcium binding.

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  • 39. 

    Which of the following are characteristics of diltiazem?

    • More potent vasodilatory than verapamil or dihydropyridines

    • Less potent vasodilatory than verapamil or dihydropyridines

    • In vasodilatory doses, less direct negative chronotropic and dromotropic effects than verapamil

    • In vasodilatory doses, more direct negative chronotropic and dromotropic effects than verapamil

    Correct Answer(s)
    A. Less potent vasodilatory than verapamil or dihydropyridines
    A. In vasodilatory doses, less direct negative chronotropic and dromotropic effects than verapamil
    Explanation
    Diltiazem is characterized by being less potent in its vasodilatory effects compared to verapamil or dihydropyridines. Additionally, in vasodilatory doses, it has less direct negative chronotropic and dromotropic effects compared to verapamil.

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  • 40. 

    When calcium enters a cardiac muscle cell, which of the following occurs?

    • Calcium binds calmodulin

    • Calcium binds troponin C

    • The interaction of actin with myosin to produce contraction is inhibited

    • The interaction of actin with myosin to produce contraction occurs uninhibited

    Correct Answer(s)
    A. Calcium binds troponin C
    A. The interaction of actin with myosin to produce contraction occurs uninhibited
    Explanation
    When calcium enters a cardiac muscle cell, it binds to troponin C. This binding of calcium to troponin C allows for the interaction between actin and myosin to occur uninhibited. This interaction is necessary for the contraction of the cardiac muscle cell.

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  • 41. 

    In vascular smooth muscle, contraction is dependent upon an increase in intracellular calcium. Which of the following occurs when calcium enters a vascular smooth muscle cell?

    • Calmodulin activates myosin LC kinase to phosphorylate myosin LC

    • Calcium binds to calmodulin

    • Calmodulin inhibits myosin LC kinase, so myosin LC cannot be phosphorylated

    • Phopshorylated myosin LC interacts with actin

    • Contraction occurs because phosphorylated myosin LC interacts with actin

    Correct Answer(s)
    A. Calmodulin activates myosin LC kinase to phosphorylate myosin LC
    A. Calcium binds to calmodulin
    A. Phopshorylated myosin LC interacts with actin
    A. Contraction occurs because phosphorylated myosin LC interacts with actin
    Explanation
    When calcium enters a vascular smooth muscle cell, it binds to calmodulin. This calcium-calmodulin complex then activates myosin LC kinase, which in turn phosphorylates myosin LC. Phosphorylated myosin LC is able to interact with actin, leading to muscle contraction. Therefore, the correct answer is that calmodulin activates myosin LC kinase to phosphorylate myosin LC, calcium binds to calmodulin, phosphorylated myosin LC interacts with actin, and contraction occurs because of this interaction.

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  • 42. 

    Which of the following is not true regarding L-type calcium channels?

    • Widespread in cardiovascular system

    • Activated when the cell is depolarized

    • Large conductance of long lasting duration

    • Inhibited by calcium channel blockers

    • Responsible for the upstroke of the cardiac action potential

    • Responsible for the plateau phase of the cardiac action potential

    Correct Answer
    A. Responsible for the upstroke of the cardiac action potential
    Explanation
    L-type calcium channels are responsible for the plateau phase of the cardiac action potential, not the upstroke. The upstroke of the cardiac action potential is primarily mediated by sodium channels. L-type calcium channels are involved in the plateau phase, where they allow for the influx of calcium ions, maintaining the depolarization of the cardiac muscle cell and prolonging the action potential.

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  • 43. 

    For which reasons do the dihydropyridine drugs not show the effects on heart rate and conduction?

    • Dihydropyridines have a preferentially selective effect on blood vessel calcium channels

    • Dihydropyridines do not effect the rate of recovery of the calcium channels

    • Dihydropyridines can show effects on heart rate and conduction

    Correct Answer(s)
    A. Dihydropyridines have a preferentially selective effect on blood vessel calcium channels
    A. Dihydropyridines do not effect the rate of recovery of the calcium channels
    Explanation
    Dihydropyridine drugs have a preferentially selective effect on blood vessel calcium channels, meaning that they primarily target and affect the calcium channels in blood vessels. This selective effect allows them to mainly influence vascular smooth muscle and cause vasodilation, which helps in reducing blood pressure. On the other hand, they do not significantly affect the rate of recovery of the calcium channels in the heart, which is responsible for heart rate and conduction. Therefore, dihydropyridine drugs do not show significant effects on heart rate and conduction.

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  • 44. 

    Which class of calcium channel blockers is primarily responsible for potentially aggravating anginal symptoms?

    Correct Answer(s)
    dihydropyridines
    Explanation
    Dihydropyridines are a class of calcium channel blockers that primarily act on the smooth muscle cells of blood vessels. They cause relaxation and dilation of the blood vessels, leading to a decrease in blood pressure. However, dihydropyridines have minimal effects on the heart's conduction system. This means that they do not affect the heart rate or contractility significantly. Because of this, dihydropyridines can potentially aggravate anginal symptoms in patients with coronary artery disease. The dilation of blood vessels can lead to increased demand for oxygen by the heart, worsening angina symptoms.

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  • 45. 

    Which of these drugs displays an oral side effect of hypotension and bradycardia?

    • Diltiazem

    • Verapamil

    • Both

    • Neither

    Correct Answer
    A. Neither
    Explanation
    INTRAVENOUS side effect! not oral! both IV verapamil and diltiazem cause hypotension and bradycardia!

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  • 46. 

    Which of the following are characteristics of the L type calcium channels?

    • Long lasting current

    • High conductance

    • Large channels

    • Enriched in the neurons

    • Enriched in cardiac and smooth muscle, in the SA node and Purkinje cells

    • Blocked by spider and snail toxins

    • Blocked by calcium channel blockers

    Correct Answer(s)
    A. Long lasting current
    A. High conductance
    A. Large channels
    A. Enriched in cardiac and smooth muscle, in the SA node and Purkinje cells
    A. Blocked by calcium channel blockers
    Explanation
    L type calcium channels have several characteristics. They exhibit a long-lasting current, meaning that the flow of calcium ions through these channels is sustained over a longer period of time compared to other types of calcium channels. They also have high conductance, allowing for a greater flow of ions. L type calcium channels are large in size, allowing for the passage of larger molecules. These channels are enriched in cardiac and smooth muscle, as well as in the SA node and Purkinje cells. They are blocked by calcium channel blockers, which are medications that inhibit the function of these channels.

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  • 47. 

    Which two drugs decrease the rate of recovery of the L-type calcium channels in the AV and SA nodes?

    Correct Answer(s)
    diltiazem
    verapamil
    Explanation
    Diltiazem and verapamil are both calcium channel blockers that decrease the rate of recovery of the L-type calcium channels in the AV and SA nodes. By blocking these channels, they reduce the influx of calcium ions into the cells, leading to a decrease in the conduction velocity and contractility of the cardiac muscles. This ultimately results in a decrease in heart rate and force of contraction, making them effective in treating conditions such as hypertension, angina, and certain arrhythmias.

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  • 48. 

    Which of the following are characteristic of N type calcium channels?

    • Large conductance

    • Small conductance

    • Intermediate conductance

    • Blocked by calcium channel blockers

    • Blocked by spider and snail toxins

    • Enriched in neurons

    • Enriched in cardiac muscle

    • Play a role in neurotransmitter release

    Correct Answer(s)
    A. Intermediate conductance
    A. Blocked by spider and snail toxins
    A. Enriched in neurons
    A. Play a role in neurotransmitter release
    Explanation
    N type calcium channels are characterized by intermediate conductance, meaning they have a moderate level of ion flow compared to other types of calcium channels. They are also blocked by spider and snail toxins, which can inhibit their function. These channels are enriched in neurons, suggesting they play a significant role in neuronal signaling. Additionally, N type calcium channels are involved in neurotransmitter release, further emphasizing their importance in neuronal communication.

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  • 49. 

    Verapamil and diltiazem preferentially bind to the inactivated state of the calcium channel. This has what effects?

    • Longer period of inactivation

    • Prevention of cycling of the channel

    • Decreased refractory period

    • Increased refractory period

    • Slows heart rate

    • Increases conduction

    • Decreases conduction

    Correct Answer(s)
    A. Longer period of inactivation
    A. Prevention of cycling of the channel
    A. Increased refractory period
    A. Slows heart rate
    A. Decreases conduction
    Explanation
    Verapamil and diltiazem preferentially binding to the inactivated state of the calcium channel leads to a longer period of inactivation, preventing the cycling of the channel. This results in an increased refractory period, slowing down the heart rate, and decreasing conduction.

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Quiz Review Timeline (Updated): Sep 2, 2023 +

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  • Current Version
  • Sep 02, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Dec 09, 2010
    Quiz Created by
    Bd13
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