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

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

Blocked by calcium channel blockers

Blocked by spider and snail toxins

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

Which of the following are characteristic of the T type calcium channel?

Found in the SA node and Purkinje cells

Blocked by calcium channel blockers

Blocked by spider and snail toxins

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

Blocked by spider and snail toxins

Play a role in neurotransmitter release

Blocked by calcium channel blockers

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

Responsible for the upstroke of the cardiac action potential

Widespread in cardiovascular system

Activated when the cell is depolarized

Large conductance of long lasting duration

Inhibited by calcium channel blockers

Responsible for the plateau phase of the cardiac action potential

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

Phopshorylated myosin LC interacts with actin

Contraction occurs because phosphorylated myosin LC interacts with actin

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

By preventing calcium entry, calcium channel blockers are thereby stopping which of the following mechanisms from occuring?

calmodulin's activation of myosin LC kinase

phosphorylated myosin LC's interaction with actin

calcium's binding to calmodulin

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

Decreased pressure and decreased cardiac afterload

Decrease pressure and decreased cardiac preload

Increased pressure and increase cardiac preload

Calcium Channel Blockers

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| By Bd13

Bd13

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Quizzes Created: 1 | Total Attempts: 1,986

Questions: 54 | Attempts: 1,999 | Updated: Sep 2, 2023

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Questions and Answers

1.

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?
- A.
  
  Nitrates
- B.
  
  Penylalkylamines
- C.
  
  Dihydropyridines
- D.
  
  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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2.

Calcium channel blockers can be used as anti-anginal drugs.
- A.
  
  True
- B.
  
  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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2
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3.

Which of the following are classified as "dihydropyridines" of the calcium channel blockers?
- A.
  
  Nicardipine
- B.
  
  Amlodipine
- C.
  
  Diltiazem
- D.
  
  Nifedipine
- E.
  
  Verapamil
- F.
  
  Felodipine
Correct Answer(s)
A. Nicardipine
B. Amlodipine
D. Nifedipine
F. Felodipine

Explanation
-PINES are dihydropyridine calcium channel blockers

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2
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4.

In addition to angina, calcium channel blockers can be used therapeutically in the treatment of which of the following diseases?
- A.
  
  Essential hypertension
- B.
  
  Cardiac arrhythmias
- C.
  
  Type II Diabetes
Correct Answer(s)
A. Essential hypertension
B. 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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1
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5.

Calcium enters excitable cells via potential or voltage-dependent calcium channels, which are similar to other ion channels.
- A.
  
  True
- B.
  
  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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6.

Which of the following is NOT a type of calcium channel?
- A.
  
  L
- B.
  
  S
- C.
  
  N
- D.
  
  T
Correct Answer
B. 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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7.

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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4
8.

Which type of calcium channel do the calcium channel blockers selectively inhibit?
- A.
  
  N
- B.
  
  T
- C.
  
  L
Correct Answer
C. 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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9.

Calcium channel blockers allow calcium movement from outside the cell to inside the cell through their channels.
- A.
  
  True
- B.
  
  False
Correct Answer
B. False

Explanation
prevent movement

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10.

Which of the following are characteristics of the L type calcium channels?
- A.
  
  Long lasting current
- B.
  
  High conductance
- C.
  
  Large channels
- D.
  
  Enriched in the neurons
- E.
  
  Enriched in cardiac and smooth muscle, in the SA node and Purkinje cells
- F.
  
  Blocked by spider and snail toxins
- G.
  
  Blocked by calcium channel blockers
Correct Answer(s)
A. Long lasting current
B. High conductance
C. Large channels
E. Enriched in cardiac and smooth muscle, in the SA node and Purkinje cells
G. 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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11.

Because L type calcium channels are enriched in the cardiac and smooth muscle, SA node, and Purkinje cells, they play an important role in __________.
- A.
  
  Contration, heart rate, and conduction
- B.
  
  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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12.

Which of the following are characteristic of the T type calcium channel?
- A.
  
  Found in the SA node and Purkinje cells
- B.
  
  Tiny, transient current
- C.
  
  Intermediate current
- D.
  
  Blocked by calcium channel blockers
- E.
  
  Blocked by spider and snail toxins
- F.
  
  Very small calcium entry
Correct Answer(s)
A. Found in the SA node and Purkinje cells
B. Tiny, transient current
F. Very small calcium entry

Explanation
The T type calcium channel is found in the SA node and Purkinje cells, which are specialized cells in the heart responsible for generating and conducting electrical impulses. It produces a tiny, transient current, meaning that it allows for a brief flow of calcium ions. Additionally, the T type calcium channel allows for a very small amount of calcium entry into the cells. Calcium channel blockers, as well as spider and snail toxins, block the T type calcium channel, preventing the flow of calcium ions.

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13.

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.
- A.
  
  True
- B.
  
  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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14.

Which of the following are characteristic of N type calcium channels?
- A.
  
  Large conductance
- B.
  
  Small conductance
- C.
  
  Intermediate conductance
- D.
  
  Blocked by calcium channel blockers
- E.
  
  Blocked by spider and snail toxins
- F.
  
  Enriched in neurons
- G.
  
  Enriched in cardiac muscle
- H.
  
  Play a role in neurotransmitter release
Correct Answer(s)
C. Intermediate conductance
E. Blocked by spider and snail toxins
F. Enriched in neurons
H. 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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15.

Which of the following is not true regarding L-type calcium channels?
- A.
  
  Widespread in cardiovascular system
- B.
  
  Activated when the cell is depolarized
- C.
  
  Large conductance of long lasting duration
- D.
  
  Inhibited by calcium channel blockers
- E.
  
  Responsible for the upstroke of the cardiac action potential
- F.
  
  Responsible for the plateau phase of the cardiac action potential
Correct Answer
E. 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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16.

Calcium channel blockers exhibit a mechanism of action in both cardiac cells and vascular muscle cells.
- A.
  
  True
- B.
  
  False
Correct Answer
A. True

Explanation
Calcium channel blockers work by blocking the influx of calcium ions into both cardiac cells and vascular muscle cells. By doing so, they decrease the contractility of the heart muscle and relax the smooth muscles in blood vessels, leading to vasodilation. This mechanism of action allows calcium channel blockers to effectively lower blood pressure and treat various cardiovascular conditions such as hypertension and angina. Therefore, the statement that calcium channel blockers exhibit a mechanism of action in both cardiac cells and vascular muscle cells is true.

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17.

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?
- A.
  
  Calmodulin activates myosin LC kinase to phosphorylate myosin LC
- B.
  
  Calcium binds to calmodulin
- C.
  
  Calmodulin inhibits myosin LC kinase, so myosin LC cannot be phosphorylated
- D.
  
  Phopshorylated myosin LC interacts with actin
- E.
  
  Contraction occurs because phosphorylated myosin LC interacts with actin
Correct Answer(s)
A. Calmodulin activates myosin LC kinase to phosphorylate myosin LC
B. Calcium binds to calmodulin
D. Phopshorylated myosin LC interacts with actin
E. 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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18.

Which of the following occurs because calcium entry into vascular smooth muscle is blocked by calcium channel blockers?
- A.
  
  Contraction
- B.
  
  Relaxation
Correct Answer
B. 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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19.

By preventing calcium entry, calcium channel blockers are thereby stopping which of the following mechanisms from occuring?
- A.
  
  Calcium's binding to calmodulin
- B.
  
  Calmodulin's activation of myosin LC kinase
- C.
  
  Phosphorylated myosin LC's interaction with actin
- D.
  
  Contraction
Correct Answer(s)
B. Calmodulin's activation of myosin LC kinase
C. Phosphorylated myosin LC's interaction with actin
D. Contraction

Explanation
Calcium channel blockers prevent calcium entry into cells. Calcium is necessary for the binding of calmodulin, which activates myosin LC kinase. This activation leads to the phosphorylation of myosin LC, allowing it to interact with actin and initiate muscle contraction. Therefore, by blocking calcium entry, calcium channel blockers prevent calmodulin's activation of myosin LC kinase, phosphorylated myosin LC's interaction with actin, and ultimately, muscle contraction.

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20.

Calcium channel blockers have a much more prominent effect in decreasing vascular smooth muscle contraction in arteries.
- A.
  
  True
- B.
  
  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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21.

The relaxation produced in coronary and peripheral vascular smooth muscle decreases peripheral resistance, which results in which of the following?
- A.
  
  Decrease pressure and decreased cardiac preload
- B.
  
  Increased pressure and increase cardiac preload
- C.
  
  Decreased pressure and decreased cardiac afterload
Correct Answer
C. 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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22.

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).
- A.
  
  True
- B.
  
  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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23.

Calcium channel blockers have a large effect on the veins, as well as the cardiac preload.
- A.
  
  True
- B.
  
  False
Correct Answer
B. False

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

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24.

Calcium entry is responsible for which phase in the action potential?
- A.
  
  Phase 0
- B.
  
  Phase 1
- C.
  
  Phase 2
Correct Answer
C. 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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25.

Calcium channels are sometimes called slow channels because of their delayed response in the cardiac action potential.
- A.
  
  True
- B.
  
  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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26.

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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27.

Because calcium channels are responsible for the plateau phase, which of the following occur when calcium channel blockers are used?
- A.
  
  More calcium enters the cell
- B.
  
  Negative inotropic effect
- C.
  
  Less calcium enters the cell
- D.
  
  Positive inotropic effect
- E.
  
  Decrease in contractility
- F.
  
  Increase in contractility
Correct Answer(s)
B. Negative inotropic effect
C. Less calcium enters the cell
E. 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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28.

How is the process for contraction in cardiac muscle different than in vascular smooth muscle?
- A.
  
  Cardiac muscle cells use calcium to bind troponin C
- B.
  
  Vascular smooth muscle cells use calcium to bind troponin C
- C.
  
  Cardiac muscle cells use calcium to bind calmodulin
- D.
  
  Vascular smooth muscle cells use calcium to bind calmodulin
Correct Answer(s)
A. Cardiac muscle cells use calcium to bind troponin C
D. 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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1
1
29.

When calcium enters a cardiac muscle cell, which of the following occurs?
- A.
  
  Calcium binds calmodulin
- B.
  
  Calcium binds troponin C
- C.
  
  The interaction of actin with myosin to produce contraction is inhibited
- D.
  
  The interaction of actin with myosin to produce contraction occurs uninhibited
Correct Answer(s)
B. Calcium binds troponin C
D. 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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2
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30.

Normally, without calcium, troponin C does which of the following in cardiac muscle cells?
- A.
  
  Inhibits myosin and actin's interactions to produce contraction
- B.
  
  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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31.

In cardiac muscle cells, which of the following occurs due to calcium channel blockers preventing calcium's entry into the cell?
- A.
  
  Relaxation
- B.
  
  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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32.

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?
- A.
  
  Dihydropyridines (Nifedipine)
- B.
  
  Phenylalkylamines (Verapamil)
- C.
  
  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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33.

For which reasons do the dihydropyridine drugs not show the effects on heart rate and conduction?
- A.
  
  Dihydropyridines have a preferentially selective effect on blood vessel calcium channels
- B.
  
  Dihydropyridines do not effect the rate of recovery of the calcium channels
- C.
  
  Dihydropyridines can show effects on heart rate and conduction
Correct Answer(s)
A. Dihydropyridines have a preferentially selective effect on blood vessel calcium channels
B. 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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34.

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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35.

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?
- A.
  
  Resting
- B.
  
  Inactivated
- C.
  
  Activated
Correct Answer
B. 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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36.

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?
- A.
  
  Decreased heart rate, decreased conduction
- B.
  
  Increased heart rate, increased conduction
- C.
  
  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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37.

Verapamil and diltiazem preferentially bind to the inactivated state of the calcium channel. This has what effects?
- A.
  
  Longer period of inactivation
- B.
  
  Prevention of cycling of the channel
- C.
  
  Decreased refractory period
- D.
  
  Increased refractory period
- E.
  
  Slows heart rate
- F.
  
  Increases conduction
- G.
  
  Decreases conduction
Correct Answer(s)
A. Longer period of inactivation
B. Prevention of cycling of the channel
D. Increased refractory period
E. Slows heart rate
G. 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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38.

Verapamil and diltiazem are sometimes called "use dependant" for which reason?
- A.
  
  Their effectiveness is dependent on the frequency of use of the drugs
- B.
  
  Their effectiveness is dependent on the frequency of use of the channels
Correct Answer
B. 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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39.

Verapamil and diltiazem are use dependent, which makes them especially effective in bradycardias.
- A.
  
  True
- B.
  
  False
Correct Answer
B. 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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40.

Which of the following are specific hemodynamic effects of dihydropyridines, like nifedipine?
- A.
  
  Increased contractility and heart rate due to reflex stimulation
- B.
  
  Vasodilation, resulting in decreased afterload
- C.
  
  Reflex increase in sympathetic stimulation of the heart
- D.
  
  Overall increase in cardiac output
Correct Answer(s)
A. Increased contractility and heart rate due to reflex stimulation
B. Vasodilation, resulting in decreased afterload
C. Reflex increase in sympathetic stimulation of the heart
D. Overall increase in cardiac output

Explanation
Overall increase in cardiac output because the negative inotropic (contractile) effect is overwhelmed by the sympathetic reflex stimulation!

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41.

Which of the following are characteristic of verapamil?
- A.
  
  Less potent vasodilatory than dihydropyridines
- B.
  
  More potent vasodilator than dihydropyridines
- C.
  
  In vasodilatory doses, more direct negative chronotropic, dromotropic, and inotropic effects than dihydropyridines
- D.
  
  In vasodilatory doses, less direct negative chronotropic, dromotropic, and inotropic effects than dihydropyridines
- E.
  
  Decrease in blood pressure
- F.
  
  Some reflex increase in sympathetic tone
- G.
  
  In impaired function patients, decreases in contractility and left ventricular function may occur
Correct Answer(s)
A. Less potent vasodilatory than dihydropyridines
C. In vasodilatory doses, more direct negative chronotropic, dromotropic, and inotropic effects than dihydropyridines
E. Decrease in blood pressure
F. Some reflex increase in sympathetic tone
G. In impaired function patients, decreases in contractility and left ventricular function may occur

Explanation
Verapamil is a calcium channel blocker that is used to treat hypertension and angina. It is less potent as a vasodilator compared to dihydropyridines, another class of calcium channel blockers. In vasodilatory doses, verapamil has more direct negative effects on heart rate (chronotropic), conduction velocity (dromotropic), and contractility (inotropic) compared to dihydropyridines. Verapamil also decreases blood pressure and may cause a reflex increase in sympathetic tone. In patients with impaired heart function, verapamil may further decrease contractility and left ventricular function.

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42.

Which of the following are characteristics of diltiazem?
- A.
  
  More potent vasodilatory than verapamil or dihydropyridines
- B.
  
  Less potent vasodilatory than verapamil or dihydropyridines
- C.
  
  In vasodilatory doses, less direct negative chronotropic and dromotropic effects than verapamil
- D.
  
  In vasodilatory doses, more direct negative chronotropic and dromotropic effects than verapamil
Correct Answer(s)
B. Less potent vasodilatory than verapamil or dihydropyridines
C. 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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43.

Which of the following drugs can be dangerous in a patient with congestive heart failure?
- A.
  
  Nifedipine
- B.
  
  Verapamil
- C.
  
  Diltiazem
Correct Answer
B. 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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44.

Calcium channel blockers can be used in which of the following conditions?
- A.
  
  Vasospastic angina
- B.
  
  Stable exertional angina
- C.
  
  Essential hypertension
- D.
  
  All of the above
- E.
  
  None of the above
Correct Answer
D. 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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45.

In stable exertional angina, calcium channel blockers are able to increase oxygen supply, as well as decrease oxygen demand.
- A.
  
  True
- B.
  
  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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46.

In vasospastic angina, calcium channel blockers primarily increase oxygen supply through coronary artery dilation to prevent vasospasms.
- A.
  
  True
- B.
  
  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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47.

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

Correct Answer
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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48.

Calcium channel blockers can be used in treating essential hypertension because of their prominent vascular effects.
- A.
  
  True
- B.
  
  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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49.

Depending on drug doses, the negative effects associated with calcium channel blockers (primarily dihydropyridines) include which of the following?
- A.
  
  Decreased diastolic pressure, decreased perfusion, decreased oxygen supply with increased vascular resistance
- B.
  
  Stronger activation of the baroreceptor reflex, reflex tachycardia, increased oxygen demand with decreased blood pressure
- C.
  
  Excessive vasodilation
Correct Answer(s)
A. Decreased diastolic pressure, decreased perfusion, decreased oxygen supply with increased vascular resistance
B. Stronger activation of the baroreceptor reflex, reflex tachycardia, increased oxygen demand with decreased blood pressure
C. Excessive vasodilation

Explanation
Calcium channel blockers, especially dihydropyridines, can cause several negative effects depending on the drug doses. These include decreased diastolic pressure, which refers to a decrease in the pressure in the arteries during the relaxation phase of the cardiac cycle. This can lead to decreased perfusion, which is the delivery of blood to the organs and tissues. Decreased oxygen supply can also occur due to reduced blood flow, and this is accompanied by increased vascular resistance, which refers to the resistance to blood flow in the blood vessels. Additionally, calcium channel blockers can cause stronger activation of the baroreceptor reflex, leading to reflex tachycardia, which is an increased heart rate. This can result in increased oxygen demand while the blood pressure decreases. Finally, excessive vasodilation can occur, causing a widening of the blood vessels beyond what is necessary, which can further contribute to decreased blood pressure.

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50.

The most common side effects of calcium channel blockers, dizziness, hypotension, headache, and facial flushing, can be attributed to which of the following?
- A.
  
  Excessive vasodilation
- B.
  
  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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Dec 09, 2010

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Calcium Channel Blockers