The Heart And Its Function

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1. Actin and myosin, striated and involuntary are descriptive terms for the

Explanation

Actin and myosin are proteins that are primarily found in muscle cells, including the myocardium, which is the muscular tissue of the heart. The term "striated" refers to the striped appearance of muscle fibers under a microscope, which is a characteristic of skeletal and cardiac muscle, including the myocardium. Additionally, the term "involuntary" means that the muscles contract and relax without conscious control, which is true for the myocardium. Therefore, the correct answer is "myocardium" because it is the tissue in the heart that contains actin and myosin, is striated, and functions involuntarily.

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The Heart And Its Function - Quiz

Being able to note difference or an abnormality in a heart can make the difference between life and death. Being that you are a cardiovascular student you must know what a normal functioning heart looks like and how to make an unhealthy one, healthy. Take this quiz on the heart... see moreand its function to see just how much you know. All the best! see less

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2. Which of the following terms describes myocardial contraction and relaxation?

Explanation

Systole and diastole are terms used to describe the contraction and relaxation of the myocardium, which is the muscular tissue of the heart. During systole, the myocardium contracts, pumping blood out of the heart and into the arteries. Diastole, on the other hand, refers to the relaxation phase of the myocardium, during which the heart fills with blood. These terms are commonly used in the context of measuring blood pressure and understanding the cardiac cycle.

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3. Which of the following statements is correct about cardiac output?

Explanation

The correct answer is that cardiac output is determined by heart rate and stroke volume. Cardiac output refers to the amount of blood pumped by the heart per minute and is influenced by both heart rate (the number of times the heart beats per minute) and stroke volume (the amount of blood pumped by the heart with each beat). When the heart rate or stroke volume increases, the cardiac output also increases, and vice versa.

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4. Increase in the strength of myocardial contraction that occurs when the heart is· stretched

Explanation

Starling's law of the heart states that the strength of myocardial contraction increases when the heart is stretched. This means that when the volume of blood entering the heart increases, the heart muscle fibers are stretched, leading to a more forceful contraction and a greater amount of blood being pumped out of the heart. This mechanism ensures that the heart is able to adapt to changes in venous return and maintain an adequate cardiac output.

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5. Determined by heart rate x stroke volume

Explanation

Cardiac output refers to the amount of blood pumped by the heart per minute. It is determined by the product of heart rate (number of heartbeats per minute) and stroke volume (volume of blood pumped by the heart with each beat). The higher the heart rate and stroke volume, the greater the cardiac output. Cardiac output is an important measure of heart function and can be used to assess the efficiency of blood circulation in the body.

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6. The phase of the cardiac cycle that refers to relaxation of the ventricles

Explanation

Diastole refers to the phase of the cardiac cycle when the ventricles are relaxed. During diastole, the ventricles fill with blood from the atria, preparing for the next contraction. This phase allows for adequate blood flow and oxygen supply to the body. Stroke volume, on the other hand, is the amount of blood pumped out of the heart with each contraction. Systole is the phase of the cardiac cycle when the ventricles contract and pump blood out of the heart.

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7. The capacity to increase cardiac output above the resting cardiac output

Explanation

Cardiac reserve refers to the ability of the heart to increase its cardiac output above the resting cardiac output. It represents the difference between the maximum cardiac output that the heart can achieve during exercise or stress and the resting cardiac output. This reserve is important as it allows the heart to meet the increased demands of the body during physical activity or in times of stress. It is influenced by factors such as heart rate, stroke volume, and contractility of the heart.

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8. Stretching the heart causes the force of myocardial contraction to increase. This stretch effect is called

Explanation

Stading's Law of the Heart states that the force of myocardial contraction increases when the heart is stretched. This phenomenon is known as the stretch effect.

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9. Beats/min

Explanation

Heart rate refers to the number of times the heart beats per minute. It is a measure of the cardiac cycle, which is the complete sequence of events in one heartbeat. The heart rate is an important factor in determining the cardiac output, which is the amount of blood pumped by the heart in one minute. Therefore, heart rate is closely related to cardiac output and is a crucial parameter in assessing cardiovascular health and function.

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10. Hepatomegaly (enlarged liver), distended jugular veins aVOs), pedal edema

Explanation

The given symptoms of hepatomegaly (enlarged liver), distended jugular veins, aVOs (atrioventricular openings), and pedal edema are indicative of right-sided heart failure. Right-sided heart failure occurs when the right side of the heart is unable to effectively pump blood to the lungs for oxygenation. This leads to a backup of blood in the veins, causing fluid accumulation in the liver (hepatomegaly), jugular veins (distended jugular veins), and lower extremities (pedal edema). Left-sided heart failure primarily affects the left side of the heart and causes different symptoms.

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11. The heart drug digitalis stimulates the parasympathetic nerve that supplies the heart. What cardiac effect is expected?

Explanation

When the parasympathetic nerve that supplies the heart is stimulated by digitalis, it causes the heart rate to slow down. This is because the parasympathetic nervous system is responsible for regulating rest and digestion, and it works in opposition to the sympathetic nervous system which controls the fight or flight response. Stimulation of the parasympathetic nerve leads to a decrease in heart rate and a relaxation of the heart muscles, resulting in a slower heart rate.

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12. During ventricular diastole

Explanation

During ventricular diastole, the heart muscles relax, and the ventricles expand. This expansion creates a low-pressure environment, allowing blood to flow into the ventricles from the atria. The semilunar valves, which separate the ventricles from the blood vessels, are closed during this phase to prevent backflow. As a result, blood fills the ventricles, preparing them for the next phase of the cardiac cycle.

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13. 'What happens when the actin and myosin in the ventricles form cross-bridges

Explanation

When the actin and myosin in the ventricles form cross-bridges, it triggers the contraction of the myocardium. The actin and myosin filaments slide past each other, causing the ventricular muscles to contract. This contraction leads to the pumping of blood out of the ventricles and into the arteries.

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14. Increase in the strength of myocardial contraction that occurs without stretching the heart

Explanation

A positive inotropic effect refers to an increase in the strength of myocardial contraction. This effect occurs without stretching the heart, meaning that it is not dependent on the volume of blood filling the heart. It can be caused by various factors such as sympathetic stimulation or the administration of certain medications. This increase in myocardial contraction strength ultimately leads to an increase in stroke volume, which is the amount of blood pumped out of the heart with each heartbeat. Therefore, the given correct answer, positive inotropic effect, accurately describes the phenomenon of increased myocardial contraction strength without stretching the heart.

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15. Sequence of events that occurs in the heart in one beat

Explanation

The cardiac cycle refers to the sequence of events that occur in the heart in one beat. It includes the contraction and relaxation of the heart chambers, as well as the opening and closing of the heart valves. During the cardiac cycle, the heart fills with blood during diastole and then pumps out the blood during systole. This process ensures that oxygenated blood is pumped to the body and deoxygenated blood is sent to the lungs for oxygenation. Therefore, the cardiac cycle is responsible for maintaining the circulation of blood throughout the body.

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16. The percentage of the end-diastolic volume (EOV) that is pumped

Explanation

Ejection fraction refers to the percentage of blood pumped out of the left ventricle of the heart with each contraction. It is calculated by dividing the stroke volume (the amount of blood pumped out) by the end-diastolic volume (the amount of blood in the ventricle before contraction). A higher ejection fraction indicates a more efficient pumping of blood and is often used as a measure of cardiac function.

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17. Phase of the cardiac cycle that refers to contraction of the heart muscle

Explanation

Systole refers to the phase of the cardiac cycle where the heart muscle contracts. During systole, the ventricles contract and pump blood out of the heart to the rest of the body. This phase is important for maintaining blood pressure and ensuring proper circulation. Diastole, on the other hand, refers to the relaxation phase of the cardiac cycle where the heart muscle relaxes and fills with blood. Heart rate, although related to the cardiac cycle, does not specifically refer to the contraction of the heart muscle.

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18. 70mL/bea

Explanation

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19. Change in heart rate

Explanation

The term "chronotropic effect" refers to the ability of a substance or factor to alter the heart rate. This means that it can either increase or decrease the heart rate. In this context, the correct answer suggests that the change in heart rate is due to the chronotropic effect. It implies that some factor or substance has influenced the heart rate, causing it to either increase or decrease. The answer does not provide any specific information about the cause or mechanism of the chronotropic effect, but it does indicate that the change in heart rate is due to this particular effect.

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20. Backup within the pulmonary capillaries causing water to accumulate in the lungs

Explanation

Left-sided heart failure occurs when the left side of the heart is unable to pump blood effectively, leading to a backup of blood within the pulmonary capillaries. This causes an increase in pressure within the capillaries, resulting in the accumulation of fluid in the lungs. This accumulation of fluid in the lungs is known as pulmonary edema. Therefore, the given answer, "left-sided heart failure," explains the situation where there is a backup within the pulmonary capillaries causing water to accumulate in the lungs.

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21. Which of the following is least likely to increase cardiac output?

Explanation

Vagal discharge refers to the activation of the vagus nerve, which has a parasympathetic effect on the heart, causing a decrease in heart rate. Since cardiac output is the product of heart rate and stroke volume, a decrease in heart rate would lead to a decrease in cardiac output. Therefore, vagal discharge is least likely to increase cardiac output.

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22. Amount of blood pumped by the heart in 1 minute

Explanation

Cardiac output refers to the amount of blood pumped by the heart in one minute. It is a measure of the efficiency and effectiveness of the heart in delivering oxygenated blood to the body's tissues. Cardiac output is calculated by multiplying the heart rate (number of heartbeats per minute) by the stroke volume (amount of blood pumped with each heartbeat). Therefore, the correct answer is cardiac output.

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23. Ventricular systole refers to

Explanation

Ventricular systole refers to the contraction of the ventricular myocardium. During this phase of the cardiac cycle, the ventricles contract, forcing blood out of the heart and into the arteries. This contraction is necessary for proper blood flow and circulation throughout the body. Ventricular depolarization, on the other hand, refers to the electrical activity that triggers the contraction, while the opening of the valves of the ventricles is a result of the contraction and allows blood to be pumped out of the heart.

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24. Pulmonary edema

Explanation

Left-sided heart failure occurs when the left side of the heart is unable to effectively pump blood to the rest of the body. This can lead to a buildup of fluid in the lungs, known as pulmonary edema. The excess fluid in the lungs causes symptoms such as difficulty breathing, coughing, and wheezing. Therefore, the correct answer is left-sided heart failure as it directly relates to the development of pulmonary edema.

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25. Most likely to say "1 can't breathe

Explanation

Left-sided heart failure occurs when the left side of the heart is unable to pump blood effectively to the rest of the body. This can lead to fluid accumulation in the lungs, causing shortness of breath and the feeling of being unable to breathe. Right-sided heart failure, on the other hand, occurs when the right side of the heart is unable to effectively pump blood to the lungs for oxygenation. Since the symptom mentioned in the question is related to breathing difficulties, it is most likely associated with left-sided heart failure.

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26. Which of the following is a consequence of backward failure associated with left-sided heart failure?

Explanation

Backward failure in left-sided heart failure refers to the inability of the left ventricle to adequately pump blood out to the systemic circulation, leading to a buildup of fluid in the pulmonary circulation. This excess fluid accumulates in the lungs, causing pulmonary edema. Pulmonary edema is characterized by symptoms such as shortness of breath, coughing, and wheezing. It can be a life-threatening condition if not promptly treated. Therefore, pulmonary edema is a consequence of backward failure associated with left-sided heart failure.

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27. A beta,-adrenergic agonist

Explanation

A beta-adrenergic agonist increases cardiac output by stimulating the beta receptors in the heart, leading to an increase in heart rate and contractility. This results in an increased amount of blood being pumped out of the heart with each beat, leading to an overall increase in cardiac output.

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28. Which of the following is an age-related cardiac change

Explanation

As individuals age, there are several changes that occur in the cardiovascular system. One of these changes is a decrease in the heart muscle's ability to respond vigorously to the demands of exercise. This means that the heart may not be able to pump blood as efficiently during physical activity, leading to decreased exercise tolerance and potential fatigue. This age-related cardiac change can result in a reduced ability to engage in strenuous activities and may require modifications in exercise routines for older individuals.

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29. Increased return of blood to the heart stretches the heart muscle, thereby

Explanation

When the return of blood to the heart increases, it stretches the heart muscle. This stretching stimulates the vagus nerve, which in turn increases stroke volume. Stroke volume refers to the amount of blood pumped out by the heart with each contraction. Therefore, the correct answer is that increased return of blood to the heart increases stroke volume.

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30. Which of the following is least characteristic of sympathetic nerve stimulation

Explanation

Sympathetic nerve stimulation is known to have several effects on the heart, including increased heart rate and increased cardiac output. However, it is least characteristic of sympathetic nerve stimulation to have an inotropic effect, which refers to the force of contraction of the heart. Inotropic effects are typically associated with the parasympathetic nervous system, while sympathetic stimulation primarily affects heart rate and cardiac output.

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31. Jugular vein distension is most associated with

Explanation

Jugular vein distension is most associated with right-sided heart failure because in this condition, the right side of the heart is unable to effectively pump blood to the lungs for oxygenation. This leads to a backup of blood in the veins, including the jugular veins in the neck, causing them to become enlarged and visible. Left wall infarct and left ventricular failure may also cause jugular vein distension, but right-sided heart failure is the most common cause. Low volume shock, on the other hand, typically does not cause jugular vein distension.

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32. The amount of blood in the ventricles at the end of its resting phase

Explanation

End diastolic volume refers to the amount of blood present in the ventricles at the end of their resting phase, just before they contract and pump blood out of the heart. It is an important measure of the heart's preload, or the amount of blood that fills the ventricles during diastole. The end diastolic volume is influenced by factors such as venous return and the ability of the ventricles to relax and fill with blood.

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33. Cor pulmonale

Explanation

Right-sided heart failure is the correct answer because cor pulmonale refers to a condition where the right side of the heart fails to pump blood effectively due to lung disease or high blood pressure in the lungs. This leads to a backup of blood in the veins and fluid accumulation in the legs and abdomen, causing symptoms such as swelling, fatigue, and shortness of breath. Left-sided heart failure, on the other hand, occurs when the left side of the heart fails to pump blood effectively and is not directly related to cor pulmonale.

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34. Which of the following occurs during ventricular systole?

Explanation

During ventricular systole, the contraction of the ventricles causes the blood to be pumped out of the ventricles and into the arteries. This is an essential part of the cardiac cycle, where the ventricles contract to push the oxygenated blood to the rest of the body. The AV valves, which are located between the atria and the ventricles, close during ventricular systole to prevent the backflow of blood into the atria. The semilunar valves, which are located between the ventricles and the arteries, open to allow the blood to flow out of the ventricles and into the arteries.

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35. Atropine, a muscarinic blocker

Explanation

Atropine, a muscarinic blocker, is known to increase heart rate. This is because it blocks the action of acetylcholine, a neurotransmitter that slows down the heart rate by stimulating muscarinic receptors. By blocking these receptors, atropine prevents the inhibitory effect of acetylcholine, resulting in an increase in heart rate.

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36. The resistance or opposition to the flow of blood

Explanation

Afterload refers to the resistance or opposition to the flow of blood from the heart into the arteries. It is the pressure that the heart must overcome in order to pump blood out into the circulatory system. When the afterload is increased, such as in conditions like hypertension, the heart has to work harder to overcome the resistance, leading to increased workload and potential complications. Therefore, afterload is an important factor in determining cardiac function and can have significant implications for overall cardiovascular health.

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37. 5000mL/min

Explanation

Cardiac output refers to the amount of blood pumped by the heart in one minute. It is measured in milliliters per minute (mL/min). This measurement is important as it helps determine the efficiency of the heart in delivering oxygenated blood to the body's tissues. In this case, the given answer of 5000mL/min indicates the volume of blood pumped by the heart per minute.

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38. Which of the following is least related to tachydysrhythmias

Explanation

Vagal discharge refers to the activation of the vagus nerve, which has a parasympathetic effect on the heart, slowing down the heart rate. Tachydysrhythmias, on the other hand, are abnormal rapid heart rhythms. Therefore, vagal discharge is least related to tachydysrhythmias as it has an opposite effect by slowing down the heart rate. Beta1 adrenergic receptor activation and (+) dromotropic effect, on the other hand, are both related to sympathetic activation and can contribute to tachydysrhythmias by increasing the heart rate.

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39. Which of the following is most likely to elicit a (+) inotropic effect, a (+) dromotropic effect and a (+) chronotropic effect?

Explanation

Sympathomimetic activity is most likely to elicit a positive inotropic effect (increased force of contraction), a positive dromotropic effect (increased conduction velocity), and a positive chronotropic effect (increased heart rate). Sympathomimetic drugs mimic the effects of the sympathetic nervous system, which is responsible for the "fight or flight" response. Activation of the sympathetic system leads to increased heart rate, increased force of contraction, and increased conduction velocity in the heart. Therefore, sympathomimetic activity is the most likely choice to produce these effects.

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40. Amount of blood pumped by the ventricle per beat

Explanation

Stroke volume refers to the amount of blood that is pumped by the ventricle of the heart with each beat. It is an important measure of cardiac function and is directly related to the cardiac output, which is the total amount of blood pumped by the heart in one minute. The cardiac reserve, on the other hand, refers to the ability of the heart to increase its output during times of increased demand, such as during exercise. While both cardiac output and cardiac reserve are related to stroke volume, they are not the same as stroke volume specifically refers to the amount of blood pumped per beat.

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41. Cyanosis, dyspnea, orthopnea

Explanation

Cyanosis, dyspnea, and orthopnea are symptoms commonly associated with left-sided heart failure. Cyanosis refers to a bluish discoloration of the skin due to inadequate oxygenation, which can occur when the heart is unable to pump enough oxygenated blood to the body. Dyspnea is shortness of breath, often experienced during physical activity or lying flat, which can result from fluid buildup in the lungs due to left-sided heart failure. Orthopnea is difficulty breathing while lying flat, which is also a common symptom of left-sided heart failure. Therefore, the correct answer is left-sided heart failure.

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42. Seventy (70) mL/beat x 72 beats/min is the amount of blood that determines the

Explanation

The given equation, Seventy (70) mL/beat x 72 beats/min, calculates the amount of blood pumped by the heart in one minute. This quantity is known as the cardiac output, which represents the volume of blood pumped by the heart per minute. Therefore, the correct answer is cardiac output.

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43. An increase venous return of blood to the heart

Explanation

An increase in venous return of blood to the heart leads to an increase in preload. Preload refers to the amount of blood in the ventricles at the end of diastole, just before the heart contracts. When venous return increases, more blood is delivered to the heart, causing the ventricles to fill up with a larger volume of blood. This increased preload stretches the cardiac muscle fibers, leading to a more forceful contraction during systole and ultimately increasing cardiac output. Therefore, the correct answer is that an increase in venous return of blood to the heart increases preload.

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44. Preload is most related to

Explanation

Preload refers to the degree of stretch of the cardiac muscle fibers just before contraction. Starling's Law of the Heart states that the force of contraction of the heart is directly proportional to the initial length of the muscle fibers. Therefore, preload is most related to Starling's Law of the Heart, as it influences the force of contraction by determining the initial length of the muscle fibers. Heart rate and SA node activity are not directly related to preload.

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45. A patient in heart failure is given a drug that is classified as a beta1 adrenergic agonist. The drug

Explanation

The drug is classified as a beta1 adrenergic agonist, which means it activates the beta1 adrenergic receptors. Activation of these receptors causes a positive inotropic effect, meaning it increases the force of contraction of the heart. Therefore, the correct answer is that the drug activates the beta1 adrenergic receptors and causes a (+) inotropic effect.

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46. Which of the following is least related to the vagus nerve

Explanation

The vagus nerve is primarily responsible for the parasympathetic nervous system, which controls rest and digestion. It also plays a role in slowing down the heart rate. However, the (+) inotropic effect refers to the increase in the force of contraction of the heart, which is not directly related to the vagus nerve. Therefore, the (+) inotropic effect is the least related to the vagus nerve among the given options.

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47. Its duration is 0.8 second with a normal resting heart rate.

Explanation

The cardiac cycle refers to the sequence of events that occur during one complete heartbeat. It includes the contraction and relaxation of the heart chambers, as well as the opening and closing of the heart valves. The duration of the cardiac cycle is typically around 0.8 seconds in individuals with a normal resting heart rate. This time period allows for efficient blood flow and ensures that the heart is able to pump an adequate amount of blood to meet the body's demands.

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48. Example hypertension

Explanation

Afterload refers to the pressure or resistance that the heart has to overcome in order to pump blood out of the left ventricle and into the systemic circulation. It is determined by factors such as vascular tone and arterial blood pressure. An increase in afterload can lead to an increased workload on the heart, as it has to generate more force to overcome the resistance. This can result in decreased stroke volume and cardiac output. Therefore, afterload is an important factor to consider in the assessment and management of hypertension.

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49. Which of the following increases stroke volume?

Explanation

An inotropic effect refers to an increase in the force of contraction of the heart muscle. When the heart contracts more forcefully, it is able to pump a greater volume of blood with each beat, leading to an increase in stroke volume. This can be beneficial in situations where the heart needs to pump more blood, such as during exercise or in response to certain medical conditions. The other options, a chronotropic effect and decreased EDV, do not directly affect the force of contraction and therefore would not increase stroke volume.

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50. If heart rate increases to 170 beats/min

Explanation

When the heart rate increases to 170 beats per minute, the length of diastole decreases. Diastole is the phase of the cardiac cycle when the heart muscle relaxes and fills with blood. As the heart rate increases, the time available for diastole decreases, leading to a shorter duration of relaxation and filling. This can affect the amount of blood that is able to enter the heart during diastole, potentially impacting cardiac output and overall cardiovascular function.

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51. A drug, such as atropine, that blocks the muscarinic receptors is most likely to

Explanation

A drug that blocks muscarinic receptors, such as atropine, is most likely to increase heart rate. Muscarinic receptors are responsible for inhibiting heart rate, so blocking these receptors would result in a decrease in the inhibitory signals and therefore an increase in heart rate.

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52. Which of the following is least related to a bradycardia

Explanation

Sympathetic nerve stimulation is least related to bradycardia because sympathetic stimulation usually increases heart rate, while bradycardia refers to a slow heart rate of less than 60 beats per minute. Bradycardia is often caused by vagal discharge, which is an increase in parasympathetic activity that slows down the heart rate.

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53. Forms the basis of Starling's law of the heart

Explanation

End diastolic volume refers to the amount of blood in the ventricles at the end of diastole, or the relaxation phase of the cardiac cycle. It is an important parameter in determining the preload, or the amount of blood that fills the heart before it contracts. Starling's law of the heart states that the force of cardiac contraction is directly proportional to the end diastolic volume, meaning that as the volume increases, the heart contracts more forcefully to pump out the increased volume of blood. Therefore, end diastolic volume forms the basis of Starling's law of the heart.

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54. Venous return

Explanation

End diastolic volume refers to the amount of blood in the ventricles at the end of diastole, or relaxation phase of the cardiac cycle. It is an important determinant of stroke volume, which is the amount of blood ejected from the ventricles with each heartbeat. A higher end diastolic volume generally leads to a higher stroke volume, as the ventricles are more filled with blood and can contract more forcefully. Therefore, end diastolic volume plays a crucial role in regulating cardiac output and overall cardiovascular function.

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55. Also called preload

Explanation

End diastolic volume refers to the amount of blood present in the ventricles at the end of diastole, before contraction. It is an important determinant of stroke volume, which is the amount of blood pumped out of the heart with each contraction. An increase in end diastolic volume leads to an increase in stroke volume, due to the Frank-Starling mechanism. This mechanism states that the heart will automatically pump out a greater volume of blood when it is filled with a larger volume of blood. Therefore, end diastolic volume is a crucial factor in cardiac function and directly affects the amount of blood pumped out of the heart.

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56. Change in myocardial contractile force that is not caused by stretch

Explanation

An inotropic effect refers to a change in the force of contraction of the heart muscle (myocardium) that is not caused by stretching of the muscle. This means that the force of contraction is altered without any change in the length or stretch of the muscle fibers. The term "inotropic" is derived from the Greek words "inon" meaning "fiber" and "tropos" meaning "turn" or "change". Therefore, an inotropic effect can be understood as a change in the contractile force of the myocardium that is independent of changes in muscle length or stretch.

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57. Norepinephrine (NE)

Explanation

Norepinephrine (NE) is a neurotransmitter and hormone that activates beta-adrenergic receptors in the sympathetic nervous system. These receptors are part of the adrenergic system, which is responsible for the fight-or-flight response. NE acts as an agonist, meaning it enhances the activity of these receptors, leading to increased heart rate, blood pressure, and other sympathetic responses. It does not activate muscarinic receptors, which are instead activated by acetylcholine. Muscarinic blockade refers to the inhibition of muscarinic receptors, which would have the opposite effect of NE activation. Therefore, the correct statement is that NE is a beta-adrenergic agonist.

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58. Which of the following is most likely to increase the ejection fraction?

Explanation

Stimulation of the sympathetic nervous system is most likely to increase the ejection fraction. The sympathetic nervous system is responsible for the "fight or flight" response, which increases heart rate and contractility. This increased contractility leads to a stronger contraction of the heart, resulting in a higher ejection fraction. On the other hand, activation of the muscarinic receptors and vagal discharge have the opposite effect, decreasing heart rate and contractility, and therefore decreasing the ejection fraction.

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59. Blockade of the effects of acetylcholine ACh on the heart

Explanation

The blockade of the effects of acetylcholine (ACh) on the heart would result in an increase in heart rate. Acetylcholine is a neurotransmitter that slows down the heart rate by binding to specific receptors in the heart. By blocking the effects of ACh, the inhibitory signals that would normally slow down the heart rate are prevented, leading to an increase in heart rate.

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60. Coronary blood flow is greatest during this phase of the cardiac cycle

Explanation

During diastole, the heart is in its relaxation phase. This is when the ventricles are filling with blood from the atria. Since the heart is relaxed and not contracting, there is less resistance to blood flow, allowing for a greater volume of blood to flow through the coronary arteries and supply oxygen and nutrients to the heart muscle. Therefore, coronary blood flow is greatest during diastole.

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61. Ability of the myocardium to match venous return and cardiac output on a beat-to-beat basis

Explanation

Starling's law of the heart refers to the ability of the myocardium (heart muscle) to adjust its force of contraction in response to changes in venous return (the amount of blood returning to the heart) and maintain a balance between venous return and cardiac output (the amount of blood pumped out of the heart per minute). This law states that as venous return increases, the myocardium stretches, leading to increased force of contraction and thus increased cardiac output. Therefore, the ability of the myocardium to match venous return and cardiac output on a beat-to-beat basis is a characteristic of Starling's law of the heart.

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62. What the ventricles are "doing" when the AV valves are open and the semilunar valves are closed

Explanation

During diastole, the ventricles are in a relaxed state. The AV valves, which are located between the atria and ventricles, are open, allowing blood to flow from the atria into the ventricles. At the same time, the semilunar valves, which are located between the ventricles and the major arteries, are closed, preventing blood from flowing back into the ventricles. This phase allows for the ventricles to fill with blood before the next contraction (systole) occurs, which will then push the blood out of the heart and into the circulation, resulting in cardiac output.

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63. A change in preload causes a change in myocardial contractile force. This response is known as a

Explanation

A change in preload, which refers to the amount of stretch on the heart muscle before it contracts, can affect the force of myocardial contraction. This phenomenon is known as Starling's law of the heart. According to this law, an increase in preload leads to an increase in myocardial contractile force, while a decrease in preload results in a decrease in contractile force. The other two options, dromotropic effect and inotropic effect, refer to different mechanisms that can affect the heart's electrical conduction and contractility, respectively, but they are not specifically related to changes in preload.

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64. Milliliters per minute describes

Explanation

Milliliters per minute is a unit commonly used to measure the volume of blood pumped by the heart in one minute, known as the cardiac output. It represents the amount of blood that is circulated throughout the body per minute and is influenced by both the stroke volume (the amount of blood pumped by the heart with each beat) and the heart rate (the number of times the heart beats per minute). Therefore, milliliters per minute is a suitable measurement for describing cardiac output.

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65. Which of the following is descriptive of stroke volume?

Explanation

Stroke volume refers to the amount of blood pumped by the heart with each heartbeat. It is measured in milliliters (ml) per beat, indicating the volume of blood ejected from the left ventricle of the heart during systole. This measurement is important in assessing cardiac function and can be used to evaluate the efficiency of the heart in pumping blood.

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66. What the ventricles are" doing" when the atrioventricular (AV) valves are closed and the semilunar valves are open

Explanation

During systole, the ventricles of the heart are contracting and pumping blood out of the heart. The closure of the atrioventricular (AV) valves prevents blood from flowing back into the atria, while the opening of the semilunar valves allows blood to be ejected into the arteries. This is a crucial phase of the cardiac cycle where blood is being forcefully pumped out of the heart to supply oxygen and nutrients to the rest of the body.

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67. For the ventricles to fill, the

Explanation

The question states that for the ventricles to fill, certain conditions must be met. One of these conditions is that the ventricles must be in diastole. Diastole is the phase of the cardiac cycle when the heart muscle relaxes and the ventricles fill with blood. During diastole, the ventricles expand and create a low pressure environment, allowing blood to flow into them from the atria. Therefore, when the ventricles are in diastole, it enables them to fill with blood.

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68. If the QRS complex does not develop, the

Explanation

When the QRS complex does not develop, it indicates that the ventricular myocardium does not contract. The QRS complex represents the depolarization and contraction of the ventricles. If this complex is absent, it means that the ventricular muscles are not contracting as they should. This can lead to a sustained muscle contraction (tetanus) in the heart, where the ventricular myocardium remains in systole and is unable to relax.

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69. Starling's law relates force of myocardial contraction with

Explanation

Starling's law states that the force of myocardial contraction is directly related to the preload, which is the degree of stretch on the heart muscle fibers just before contraction. Preload is determined by the volume of blood returning to the heart, also known as the end diastolic volume. As the volume of blood increases, the heart muscle fibers are stretched, leading to a more forceful contraction and increased cardiac output. Therefore, Starling's law establishes a relationship between preload and the force of myocardial contraction, not heart rate or end systolic volume.

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70. Three-pillow dyspnea

Explanation

Left-sided heart failure is the correct answer because three-pillow dyspnea is a symptom commonly associated with this condition. Three-pillow dyspnea refers to the need to prop oneself up with three pillows or more in order to breathe comfortably. Left-sided heart failure occurs when the left side of the heart is unable to effectively pump blood to the rest of the body, leading to fluid accumulation in the lungs. This fluid buildup can cause difficulty breathing, leading to the need for extra pillows for support. Right-sided heart failure, on the other hand, typically causes fluid accumulation in the legs and abdomen rather than the lungs.

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71. An elevation in pulmonary artery pressure is most likely to cause

Explanation

An elevation in pulmonary artery pressure is most likely to cause right ventricular hypertrophy. When the pressure in the pulmonary artery increases, the right ventricle has to work harder to pump blood into the pulmonary circulation. This increased workload leads to the thickening and enlargement of the right ventricle, known as right ventricular hypertrophy. This adaptation helps the right ventricle cope with the increased pressure and maintain adequate blood flow to the lungs.

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72. Phase of the cardiac cycle that shortens most in response to tachycardia

Explanation

During tachycardia, the heart rate increases significantly. In order to maintain an adequate amount of blood flow, the duration of diastole, the phase when the heart relaxes and fills with blood, is shortened. This allows for a quicker filling of the ventricles, ensuring that enough blood is pumped out during systole, the phase when the heart contracts. Therefore, diastole is the phase of the cardiac cycle that shortens the most in response to tachycardia.

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73. Change in the rate or speed of the cardiac impulse that travels through the conduction system of the heart

Explanation

The correct answer is "dromotropic effect." The term "dromotropic effect" refers to a change in the rate or speed of the cardiac impulse as it travels through the conduction system of the heart. This effect specifically relates to the conduction velocity of the electrical signals in the heart, affecting the timing of electrical activation and the coordination of heart contractions. It does not directly affect the strength or force of the heart's contractions (inotropic effect) or the heart rate (chronotropic effect).

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74. Consequence of chronic lung disease such as emphysema and asthma

Explanation

Chronic lung diseases such as emphysema and asthma can lead to right-sided heart failure. These lung conditions can cause increased pressure in the pulmonary arteries, leading to pulmonary hypertension. Over time, this increased pressure can strain the right side of the heart, causing it to weaken and eventually fail. As a result, the heart is unable to effectively pump blood to the lungs, leading to symptoms such as fluid retention, swelling in the legs and abdomen, and difficulty breathing. Left-sided heart failure, on the other hand, is typically caused by conditions such as coronary artery disease or high blood pressure.

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75. Most likely to develop in response to chronic systemic hypertension

Explanation

Left-sided heart failure is the most likely to develop in response to chronic systemic hypertension. Chronic systemic hypertension causes the heart to work harder to pump blood against increased resistance, leading to the development of left-sided heart failure. This occurs when the left ventricle of the heart is unable to effectively pump blood out to the rest of the body, resulting in fluid accumulation in the lungs and other symptoms associated with heart failure. Right-sided heart failure may also develop as a result of left-sided heart failure, but it is not directly caused by chronic systemic hypertension.

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76. Bradycardia is most likely to be caused by

Explanation

Bradycardia refers to a slower than normal heart rate. Vagal discharge is a likely cause of bradycardia because it involves the overstimulation of the vagus nerve, which is responsible for controlling heart rate. When the vagus nerve is overactive, it releases excessive acetylcholine, which slows down the heart rate. This can occur due to various reasons such as certain medications, heart diseases, or increased pressure in the skull. Parasympatholytic effect refers to blocking the parasympathetic nervous system, which would actually increase heart rate rather than causing bradycardia. Beta1 adrenergic receptor activation also increases heart rate rather than slowing it down.

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77. Which of the following is least likely to be used in the treatment of left ventricular failure and pulmonary edema?

Explanation

Left ventricular failure and pulmonary edema are conditions characterized by fluid overload and impaired cardiac function. The primary goal of treatment is to reduce fluid volume and improve cardiac output. Inotropic agents like digoxin and dopamine increase the force of cardiac contractions, improving cardiac output. Diuretics like furosemide help in removing excess fluid from the body. On the other hand, peripheral vasoconstrictors like norepinephrine would further increase peripheral resistance, potentially worsening the condition by increasing the afterload on the heart. Therefore, a peripheral vasoconstrictor is least likely to be used in the treatment of left ventricular failure and pulmonary edema.

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78. Under what condition is end-diastolic volume (EDV) most likely to increase while ejection fraction decreases?

Explanation

In heart failure, the heart is unable to pump enough blood to meet the body's needs. This can lead to an increase in end-diastolic volume (EDV), which is the amount of blood in the ventricles at the end of diastole. As the heart becomes weaker and less efficient, it is unable to effectively eject the increased volume of blood, resulting in a decrease in ejection fraction. Ejection fraction is the percentage of blood pumped out of the ventricles with each heartbeat. Therefore, in heart failure, EDV is most likely to increase while ejection fraction decreases.

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79. Which of the following is most likely to cause an elevation of pulmonary capillary hydrostatic pressure?

Explanation

Left ventricular failure is most likely to cause an elevation of pulmonary capillary hydrostatic pressure. In left ventricular failure, the heart's ability to pump blood effectively is compromised, leading to an increase in pressure within the left ventricle. This elevated pressure is then transmitted back into the pulmonary circulation, causing an increase in pulmonary capillary hydrostatic pressure. This can result in fluid accumulation in the lungs, leading to symptoms such as shortness of breath and pulmonary edema.

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80. Venodilation

Explanation

Venodilation refers to the widening of blood vessels, specifically the veins. When the veins dilate, they can hold more blood, which decreases the amount of blood returning to the heart (preload). Therefore, venodilation decreases preload.

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81. Digoxin is a (+) inotropic agent and therefore

Explanation

Digoxin is a positive inotropic agent, meaning it enhances the force of contraction of the heart muscle. By increasing the force of contraction, digoxin promotes the ejection of a larger volume of blood from the heart with each beat. This leads to an increase in cardiac output, which is the amount of blood pumped by the heart per minute. Therefore, the correct answer is that digoxin increases cardiac output.

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82. The amount of blood in the ventricle at the end of its resting phase is the

Explanation

Preload refers to the amount of blood in the ventricle at the end of its resting phase, just before it contracts. It is determined by the amount of blood returning to the heart from the body and is influenced by factors such as venous return and filling pressures. Preload is an important determinant of stroke volume, which is the amount of blood pumped out of the heart with each contraction. Therefore, the correct answer is preload.

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83. A chronic elevation in afterload, as in systemic hypertension, is most likely to cause

Explanation

A chronic elevation in afterload, as in systemic hypertension, can lead to left ventricular hypertrophy. This occurs because the heart has to work harder to pump blood against the increased resistance in the arteries. Over time, the increased workload causes the left ventricle to thicken and enlarge. This can eventually lead to heart failure and the development of a left-to-right shunt, where blood flows from the higher pressure left side of the heart to the lower pressure right side. Cor pulmonale, on the other hand, is typically caused by chronic lung disease and is not directly related to afterload.

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Actin and myosin, striated and involuntary are...
Which of the following terms describes...
Which of the following statements is correct about cardiac output?
Increase in the strength of myocardial...
Determined by heart rate x stroke volume
The phase of the cardiac cycle that...
The capacity to increase cardiac output...
Stretching the heart causes the force of...
Beats/min
Hepatomegaly (enlarged liver),...
The heart drug digitalis stimulates the...
During ventricular diastole
'What happens when the actin and myosin in...
Increase in the strength of myocardial...
Sequence of events that occurs in the heart in one beat
The percentage of the end-diastolic volume (EOV) that is pumped
Phase of the cardiac cycle that refers to...
70mL/bea
Change in heart rate
Backup within the pulmonary...
Which of the following is least likely to increase cardiac output?
Amount of blood pumped by the heart in 1 minute
Ventricular systole refers to
Pulmonary edema
Most likely to say "1 can't breathe
Which of the following is a consequence of backward failure associated...
A beta,-adrenergic agonist
Which of the following is an age-related cardiac change
Increased return of blood to the heart stretches the heart muscle,...
Which of the following is least characteristic of sympathetic nerve...
Jugular vein distension is most associated with
The amount of blood in the ventricles at the end of its resting phase
Cor pulmonale
Which of the following occurs during ventricular systole?
Atropine, a muscarinic blocker
The resistance or opposition to the flow of blood
5000mL/min
Which of the following is least related to tachydysrhythmias
Which of the following is most likely to elicit a (+) inotropic...
Amount of blood pumped by the ventricle per beat
Cyanosis, dyspnea, orthopnea
Seventy (70) mL/beat x 72 beats/min is the...
An increase venous return of blood to the heart
Preload is most related to
A patient in heart failure is given a drug that is classified as a...
Which of the following is least related to the vagus nerve
Its duration is 0.8 second with a normal resting heart rate.
Example hypertension
Which of the following increases stroke volume?
If heart rate increases to 170 beats/min
A drug, such as atropine, that blocks the...
Which of the following is least related to a bradycardia
Forms the basis of Starling's law of the heart
Venous return
Also called preload
Change in myocardial contractile force that is not caused by stretch
Norepinephrine (NE)
Which of the following is most likely to increase...
Blockade of the effects of acetylcholine ACh on the heart
Coronary blood flow is greatest during this phase of the cardiac cycle
Ability of the myocardium to match...
What the ventricles are "doing"...
A change in preload causes a change in myocardial contractile force....
Milliliters per minute describes
Which of the following is descriptive of stroke volume?
What the ventricles are" doing" when...
For the ventricles to fill, the
If the QRS complex does not develop, the
Starling's law relates force of myocardial contraction with
Three-pillow dyspnea
An elevation in pulmonary artery pressure is most likely to cause
Phase of the cardiac cycle that shortens...
Change in the rate or speed of the...
Consequence of chronic lung disease such as emphysema and asthma
Most likely to develop in response to chronic systemic hypertension
Bradycardia is most likely to be caused by
Which of the following is least likely to be used in the treatment of...
Under what condition is end-diastolic volume (EDV) most likely to...
Which of the following is most likely to cause an elevation of...
Venodilation
Digoxin is a (+) inotropic agent and therefore
The amount of blood in the ventricle at the end of its resting phase...
A chronic elevation in afterload, as in systemic...
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