A&p Ch. 18 - Heart & Cardiovascular Function

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  • 1/154 Questions

    Which of the following would you expect to have the lowest resting heart rate?

    • A trained athlete
    • An unconditioned adult
    • A person with heart failure
    • A teenager with a sedentary lifestyle
    • An 80-year-old woman
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A&p Ch. 18 - Heart & Cardiovascular Function - Quiz
About This Quiz

The heart is more than just an instrument of love – it’s the most important organ in our bodies, beating blood all around and ensuring we keep ticking away like a fully functioning clock. What do you know about it? Take this quiz on A&P Ch. 18 – Heart & Cardiovascular Function now!

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  • 2. 

    Heart rate is controlled by neurons of the cardiovascular center located in the

    • Pons.

    • Thalamus.

    • Medulla oblongata.

    • Hypothalamus.

    • Higher centers.

    Correct Answer
    A. Medulla oblongata.
    Explanation
    The correct answer is medulla oblongata. The medulla oblongata is responsible for controlling and regulating many vital functions of the body, including heart rate. It contains the cardiovascular center, which consists of specialized neurons that receive signals from the body and adjust the heart rate accordingly. These neurons can increase or decrease the heart rate in response to various factors such as stress, exercise, or changes in blood pressure. Therefore, the medulla oblongata plays a crucial role in maintaining the appropriate heart rate to meet the body's needs.

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  • 3. 

    When will the blood pressure be greater?

    • When the peripheral vessels dilate

    • When the peripheral vessels constrict

    Correct Answer
    A. When the peripheral vessels constrict
    Explanation
    When the peripheral vessels constrict, it causes the blood vessels to narrow, resulting in an increase in blood pressure. This is because the constriction of the vessels increases the resistance to blood flow, forcing the heart to pump harder to maintain the same level of blood flow. As a result, the blood pressure rises. Conversely, when the peripheral vessels dilate, the blood vessels widen, reducing the resistance to blood flow and leading to a decrease in blood pressure. Therefore, the blood pressure will be greater when the peripheral vessels constrict.

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  • 4. 

    The heart is innervated by ________ nerves.

    • Parasympathetic.

    • Sympathetic.

    • Both parasympathetic and sympathetic.

    • Neither parasympathetic nor sympathetic

    • Somatomotor

    Correct Answer
    A. Both parasympathetic and sympathetic.
    Explanation
    The heart is innervated by both parasympathetic and sympathetic nerves. The parasympathetic nervous system, through the vagus nerve, slows down the heart rate and decreases the force of contractions. On the other hand, the sympathetic nervous system, through the cardiac accelerator nerves, increases the heart rate and enhances the force of contractions. Therefore, both systems work together to regulate the heart's activity and maintain proper functioning.

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  • 5. 

    Arteriosclerosis can lead to

    • Hypertension.

    • Stroke.

    • Coronary artery disease.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Arteriosclerosis is a condition characterized by the hardening and narrowing of the arteries due to the buildup of plaque. This can lead to hypertension, which is high blood pressure, as the narrowed arteries make it harder for blood to flow through them. Additionally, the plaque buildup can cause blockages in the arteries supplying blood to the brain, leading to a stroke. Furthermore, if the coronary arteries, which supply blood to the heart, are affected by arteriosclerosis, it can result in coronary artery disease, which can lead to chest pain, heart attacks, and other heart-related problems. Therefore, all of the above conditions can be caused by arteriosclerosis.

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  • 6. 

    Which of the following affects blood flow through the body?

    • Blood viscosity

    • Vessel diameter

    • Turbulence

    • Vascular resistance

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    Blood flow through the body is affected by several factors. Blood viscosity refers to the thickness or stickiness of the blood, which can impede its flow. Vessel diameter plays a significant role as narrower vessels result in increased resistance to blood flow. Turbulence occurs when blood flows irregularly, causing disruptions in the smooth flow. Vascular resistance refers to the overall resistance encountered by blood as it flows through the blood vessels. Therefore, all of these factors (blood viscosity, vessel diameter, turbulence, and vascular resistance) affect blood flow through the body.

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  • 7. 

    The ________ ventricle has a greater workload than the ________.

    • Left; right ventricle

    • Right; left ventricle

    • Right; systemic circulation

    • All of the above

    • None of the above

    Correct Answer
    A. Left; right ventricle
    Explanation
    The left ventricle has a greater workload than the right ventricle. This is because the left ventricle is responsible for pumping oxygenated blood to the rest of the body through the systemic circulation, which requires more force. The right ventricle, on the other hand, pumps deoxygenated blood to the lungs for oxygenation, which requires less force. Therefore, the left ventricle has a higher workload compared to the right ventricle.

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  • 8. 

    Which of the following are characteristics of cardiovascular regulation?

    • Blood flow through tissues meets the demand for oxygen.

    • Blood flow changes to match tissue responses.

    • Changes occur without drastically altering blood pressure.

    • Blood flow through tissues meets the demand for nutrients.

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    The characteristics of cardiovascular regulation include blood flow through tissues meeting the demand for oxygen and nutrients, blood flow changing to match tissue responses, and these changes occurring without drastically altering blood pressure.

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  • 9. 

    When the left ventricle contracts, the diameter of the ventricular chamber

    • Increases.

    • Decreases.

    • Remains the same.

    Correct Answer
    A. Decreases.
    Explanation
    During left ventricle contraction, also known as systole, the myocardium contracts, causing the ventricular chamber to decrease in size. This reduction in diameter ensures that blood is forcefully ejected into the aorta and circulated to the rest of the body. The contraction of the left ventricle helps maintain blood pressure and facilitates efficient blood flow throughout the cardiovascular system. Therefore, the correct answer is that the diameter of the ventricular chamber decreases during left ventricle contraction.

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  • 10. 

    The hormone that produces cardiovascular effects similar to activation of the sympathetic nervous system is:

    • Acetylcholine.

    • Epinephrine.

    • Bradykinin.

    • Tachykinin.

    • Sympathetic neuropeptide.

    Correct Answer
    A. Epinephrine.
    Explanation
    Epinephrine is the correct answer because it is a hormone that is released by the adrenal glands during times of stress or excitement. It activates the sympathetic nervous system, which is responsible for the "fight or flight" response. Epinephrine increases heart rate, constricts blood vessels, and raises blood pressure, all of which are cardiovascular effects similar to the activation of the sympathetic nervous system. Acetylcholine, bradykinin, tachykinin, and sympathetic neuropeptide do not produce these specific cardiovascular effects.

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  • 11. 

    Stroke volume depends on

    • End-diastolic volume.

    • The contractility of the ventricle.

    • The pressure required to pump blood into the aorta.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Stroke volume is the amount of blood pumped out of the heart with each beat. It is influenced by multiple factors, including end-diastolic volume, which is the amount of blood in the ventricles at the end of diastole. A higher end-diastolic volume allows for a greater stretch of the ventricles, resulting in a more forceful contraction and increased stroke volume. The contractility of the ventricle also plays a role in stroke volume, as a stronger contraction can pump out more blood. Additionally, the pressure required to pump blood into the aorta affects stroke volume, as higher pressure can help push more blood out of the heart. Therefore, all of these factors contribute to determining stroke volume.

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  • 12. 

    In the middle of the thoracic cavity is a region occupied by the heart, great vessels, thymus, esophagus, and trachea called the

    • Pleural space.

    • Pericardial space.

    • Mediastinum.

    • Cardiac notch.

    • Ventral cavity.

    Correct Answer
    A. Mediastinum.
    Explanation
    The correct answer is mediastinum. The question is asking for the region in the middle of the thoracic cavity that is occupied by various structures including the heart, great vessels, thymus, esophagus, and trachea. This region is known as the mediastinum. The other options, such as pleural space, pericardial space, cardiac notch, and ventral cavity, do not accurately describe this specific region in the thoracic cavity.

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  • 13. 

    The atrioventricular valves permit blood flow

    • In one direction only.

    • In both directions.

    • In many directions.

    • In opposite directions on the right and left.

    • None of the above.

    Correct Answer
    A. In one direction only.
    Explanation
    The atrioventricular valves are located between the atria and ventricles of the heart. Their main function is to prevent the backflow of blood from the ventricles back into the atria during ventricular contraction. This ensures that blood flows in one direction only, from the atria to the ventricles.

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  • 14. 

    When the semilunar valves close, the AV valves then

    • Close.

    • Open.

    • Make the third heart sound.

    • All of the above

    • None of the above

    Correct Answer
    A. Open.
    Explanation
    When the semilunar valves close, it indicates the end of ventricular systole and the beginning of ventricular diastole. During this phase, the atria fill with blood and the pressure inside the ventricles decreases. As a result, the AV valves open, allowing blood to flow from the atria into the ventricles. Therefore, the correct answer is "open."

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  • 15. 

    Which of the following would have the greater effect on vascular resistance?

    • Doubling the length of a blood vessel

    • Decreasing the diameter of a blood vessel by ½

    • Neither would be greater.

    Correct Answer
    A. Decreasing the diameter of a blood vessel by ½
    Explanation
    Decreasing the diameter of a blood vessel by ½ would have a greater effect on vascular resistance compared to doubling the length of a blood vessel. Vascular resistance is directly proportional to the length of the blood vessel and inversely proportional to the fourth power of the radius of the blood vessel. Therefore, decreasing the diameter of a blood vessel by ½ would significantly increase the resistance to blood flow, while doubling the length of a blood vessel would have a less pronounced effect on resistance.

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  • 16. 

    The continual movement of fluid through the interstitial spaces produced by capillary filtration serves which of the following functions?

    • Accelerates the distribution of nutrients and hormones

    • Assists the transport of insoluble substances that cannot enter the capillaries

    • Helps carry toxins and bacteria to cells of the immune system

    • Flushes hormones and wastes from the interstitial spaces

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    The continual movement of fluid through the interstitial spaces helps in the distribution of nutrients and hormones, as it accelerates their transport. It also assists in the transport of insoluble substances that cannot enter the capillaries. Additionally, this movement helps carry toxins and bacteria to the cells of the immune system, aiding in their removal. Moreover, it flushes hormones and wastes from the interstitial spaces. Therefore, all of the given functions are served by the continual movement of fluid through the interstitial spaces.

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  • 17. 

    Edema is favored when

    • The plasma concentration of protein is reduced.

    • Endothelial permeability goes up.

    • Capillary hydrostatic pressure is elevated.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Edema is the accumulation of fluid in the tissues, and it can occur when any or all of the mentioned conditions are present. When the plasma concentration of protein is reduced, there is a decrease in the oncotic pressure, which normally helps to draw fluid back into the capillaries. When endothelial permeability increases, it allows more fluid to leak out of the capillaries and into the tissues. Elevated capillary hydrostatic pressure can also push more fluid out of the capillaries. Therefore, all of these factors can contribute to the development of edema.

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  • 18. 

    The earlike extension of the atrium is the

    • Ventricle.

    • Coronary sinus.

    • Coronary sulcus.

    • Auricle.

    • Atricle.

    Correct Answer
    A. Auricle.
    Explanation
    The correct answer is "auricle." The earlike extension of the atrium is called the auricle. It is a small, muscular pouch that helps to increase the capacity of the atrium, allowing it to hold more blood. The auricle also helps to direct blood flow into the atrium and prevent backflow.

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  • 19. 

    The function of the atrium is to

    • Collect blood.

    • Pump blood to the lungs.

    • Pump blood into the systemic circuit

    • Pump blood to the ventricle

    • Collect blood and pump blood to the ventricle.

    Correct Answer
    A. Collect blood and pump blood to the ventricle.
    Explanation
    The atrium has two main functions: to collect blood and to pump blood to the ventricle. It receives blood from the veins and acts as a holding chamber, allowing blood to flow into the ventricle when it contracts. Therefore, the correct answer is that the atrium collects blood and pumps it to the ventricle.

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  • 20. 
    Use Figure 18-1 to answer the following questions: 34) Identify the structure labeled "19." - ProProfs

    Use Figure 18-1 to answer the following questions: 34) Identify the structure labeled "19."

    • Tricuspid valve

    • Pulmonary semilunar valves

    • Aortic semilunar valve

    • Bicuspid valves

    • Ligamentum arteriosum

    Correct Answer
    A. Pulmonary semilunar valves
    Explanation
    The structure labeled "19" in Figure 18-1 is the pulmonary semilunar valves.

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  • 21. 

    Which of the following is greater during left ventricular systole?

    • The peak pressure in the ventricle

    • The peak pressure in the aorta

    • Neither is greater.

    Correct Answer
    A. The peak pressure in the ventricle
    Explanation
    During left ventricular systole, the ventricle contracts to pump blood out into the aorta. This contraction generates a peak pressure within the ventricle, known as the peak ventricular pressure. This pressure is greater than the peak pressure in the aorta because the ventricle needs to overcome the resistance offered by the aorta to push blood out into the systemic circulation. Therefore, the peak pressure in the ventricle is greater during left ventricular systole.

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  • 22. 

    The following are structural components of the conducting system of the heart. 1. Purkinje fibers 2. AV bundle 3. AV node 4. SA node 5. bundle branches The sequence in which excitation would move through this system is

    • 1, 4, 3, 2, 5.

    • 3, 2, 4, 5, 1.

    • 3, 5, 4, 2, 1.

    • 4, 3, 2, 5, 1.

    • 4, 2, 3, 5, 1.

    Correct Answer
    A. 4, 3, 2, 5, 1.
    Explanation
    The correct sequence in which excitation would move through the conducting system of the heart is 4, 3, 2, 5, 1. This is because the SA node, located in the right atrium, initiates the electrical impulse that starts each heartbeat. The impulse then travels to the AV node, located in the atrial septum, which delays the impulse to allow for atrial contraction before passing it on to the AV bundle. The AV bundle then divides into the bundle branches, which conduct the impulse towards the Purkinje fibers. Finally, the Purkinje fibers distribute the impulse throughout the ventricles, causing them to contract.

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  • 23. 

    Cardiac output is increased by

    • More sympathetic stimulation.

    • Increased end-diastolic volume.

    • Increased stroke volume.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    The correct answer is "all of the above" because sympathetic stimulation increases the heart rate and contractility, leading to an increase in stroke volume and cardiac output. Increased end-diastolic volume, also known as preload, stretches the myocardium and allows for a greater force of contraction, resulting in an increase in stroke volume and cardiac output. Thus, all three factors mentioned in the options contribute to an increase in cardiac output.

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  • 24. 

    Turbulent blood flow occurs

    • When there are irregularities in the vessel wall.

    • At high flow rates.

    • When there are sudden changes in vessel diameter.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Turbulent blood flow can occur due to irregularities in the vessel wall, high flow rates, and sudden changes in vessel diameter. Irregularities in the vessel wall can disrupt the smooth flow of blood, causing turbulence. High flow rates can also disrupt the laminar flow of blood, leading to turbulence. Additionally, sudden changes in vessel diameter can create disturbances in blood flow, resulting in turbulence. Therefore, all of the above options can contribute to the occurrence of turbulent blood flow.

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  • 25. 

    Materials can move across capillary walls by

    • Diffusion.

    • Filtration.

    • Reabsorption.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    Materials can move across capillary walls by diffusion, filtration, and reabsorption. Diffusion refers to the movement of molecules from an area of higher concentration to an area of lower concentration. Filtration occurs when fluid and solutes are forced through a membrane by hydrostatic pressure. Reabsorption is the process by which water and solutes are reabsorbed back into the bloodstream from the filtrate. Therefore, all of the above options are correct explanations for the movement of materials across capillary walls.

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  • 26. 

    During exercise

    • Vasodilation occurs at the active skeletal muscles.

    • Venous return increases.

    • Both cardiac output and stroke volume increase.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    During exercise, the body requires more oxygen and nutrients to be delivered to the active skeletal muscles. Vasodilation occurs at the active skeletal muscles, which means that the blood vessels in these muscles widen, allowing for increased blood flow and delivery of oxygen and nutrients. This increased blood flow also leads to an increase in venous return, which is the amount of blood returning to the heart. As a result, both cardiac output (the amount of blood pumped by the heart per minute) and stroke volume (the amount of blood pumped by the heart per beat) increase. Therefore, all of the above statements are correct.

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  • 27. 

    After losing 25 percent of blood volume in a motorcycle accident, which of the following compensatory responses would occur?

    • Increased heart rate

    • Increase of contractility

    • Vasoconstriction of the body wall

    • Venoconstriction of skin vessels

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    After losing 25 percent of blood volume in a motorcycle accident, the body would undergo compensatory responses to maintain blood pressure and perfusion. Increased heart rate would occur to pump the remaining blood more rapidly. Increase of contractility would help the heart to pump blood more forcefully. Vasoconstriction of the body wall would occur to redirect blood flow to vital organs. Venoconstriction of skin vessels would reduce blood flow to the skin and help conserve blood volume. Therefore, all of the above compensatory responses would occur.

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  • 28. 

    Pacemaker cells isolated from the SA node generate action potentials at ________ beats per minute.

    • 20-40

    • 40-60

    • 80-100

    • 100-140

    • 140-180

    Correct Answer
    A. 80-100
    Explanation
    Pacemaker cells isolated from the SA node generate action potentials at a rate of 80-100 beats per minute. These cells are responsible for initiating the electrical signals that regulate the heartbeat. The SA node, located in the right atrium of the heart, acts as the natural pacemaker and sets the rhythm for the rest of the heart. A normal resting heart rate falls within the range of 60-100 beats per minute, with the SA node firing at a rate of 60-100 times per minute. Therefore, the correct answer is 80-100 beats per minute.

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  • 29. 

    ________ is to slow heart rate as ________ is to fast heart rate.

    • Tachycardia; bradycardia

    • Bradycardia; cardiomyopathy

    • Bradycardia; tachycardia

    • Cardiac tamponade; bradycardia

    • None of the above

    Correct Answer
    A. Bradycardia; tachycardia
    Explanation
    Bradycardia refers to a slow heart rate, while tachycardia refers to a fast heart rate. This means that the correct answer is "Bradycardia; tachycardia" as it correctly pairs the terms that represent slow and fast heart rates respectively.

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  • 30. 

    Exchange between a blood vessel and the cells that surround it can occur only in

    • Arteries.

    • Arterioles.

    • Veins.

    • Venules.

    • Capillaries

    Correct Answer
    A. Capillaries
    Explanation
    Capillaries are the smallest blood vessels in the body and have thin walls that allow for the exchange of oxygen, nutrients, and waste products between the blood and the surrounding cells. Arteries, arterioles, veins, and venules do not have the same level of permeability as capillaries, and therefore, exchange between blood vessels and surrounding cells primarily occurs in capillaries.

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  • 31. 

    The right ventricle pumps blood to the

    • Right and left lungs.

    • Left ventricle.

    • Left atrium.

    • Aorta.

    • Right atrium.

    Correct Answer
    A. Right and left lungs.
    Explanation
    The right ventricle pumps blood to both the right and left lungs. This is because the right ventricle receives deoxygenated blood from the right atrium and pumps it to the lungs through the pulmonary artery. In the lungs, the blood picks up oxygen and gets rid of carbon dioxide before returning to the heart. Therefore, the right ventricle is responsible for pumping blood to both lungs.

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  • 32. 

    The left ventricle pumps blood to the

    • Lungs.

    • Right ventricle.

    • Right atrium.

    • Aorta.

    • Pulmonary circuit.

    Correct Answer
    A. Aorta.
    Explanation
    The left ventricle is responsible for pumping oxygenated blood from the heart to the rest of the body through the aorta, the largest artery in the body. The aorta carries the oxygenated blood to all the organs and tissues, ensuring that they receive the necessary oxygen and nutrients for proper functioning.

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  • 33. 

    The pulmonary arteries carry blood to the

    • Heart.

    • Lungs.

    • Brain.

    • Intestines.

    • Liver.

    Correct Answer
    A. Lungs.
    Explanation
    The correct answer is "lungs" because the pulmonary arteries are responsible for carrying deoxygenated blood from the heart to the lungs, where it can receive oxygen and get rid of carbon dioxide. This oxygenated blood is then returned to the heart to be pumped to the rest of the body.

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  • 34. 

    The pulmonary veins carry blood to the

    • Heart.

    • Lungs.

    • Brain.

    • Intestines.

    • Liver.

    Correct Answer
    A. Heart.
    Explanation
    The pulmonary veins carry blood to the heart. This is because the pulmonary veins are responsible for transporting oxygenated blood from the lungs back to the heart so that it can be pumped to the rest of the body. The heart then distributes this oxygenated blood to the various organs and tissues, allowing them to receive the necessary oxygen and nutrients for proper functioning.

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  • 35. 
    Use Figure 18-1 to answer the following questions: Identify the structure labeled "6." - ProProfs

    Use Figure 18-1 to answer the following questions: Identify the structure labeled "6."

    • Cusp of tricuspid valve

    • Pulmonary semilunar valve

    • Aortic semilunar valve

    • Bicuspid valve

    • Ligamentum arteriosum

    Correct Answer
    A. Cusp of tricuspid valve
    Explanation
    The structure labeled "6." in Figure 18-1 is the cusp of the tricuspid valve.

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  • 36. 

    The bicuspid or mitral valve is located

    • In the opening of the aorta.

    • In the opening of the pulmonary trunk.

    • Where the venae cavae join the right atrium.

    • Between the right atrium and right ventricle.

    • Between the left atrium and left ventricle.

    Correct Answer
    A. Between the left atrium and left ventricle.
    Explanation
    The bicuspid or mitral valve is located between the left atrium and left ventricle. This valve prevents the backflow of blood from the left ventricle to the left atrium during the contraction of the heart. It consists of two leaflets or cusps, which open and close to regulate the flow of blood. The location of the bicuspid valve between the left atrium and left ventricle ensures that oxygenated blood is pumped out of the left ventricle and into the systemic circulation, while preventing any backflow into the atrium.

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  • 37. 

    To defend blood volume against dehydration, the body

    • Accelerates reabsorption of water at the kidneys.

    • Experiences a recall of interstitial fluids.

    • Experiences an increase in the blood colloidal osmotic pressure.

    • Increases water intake.

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    The body defends blood volume against dehydration by implementing multiple mechanisms. It accelerates reabsorption of water at the kidneys, which helps retain water in the body. It also experiences a recall of interstitial fluids, which are the fluids surrounding the cells, to maintain blood volume. Additionally, there is an increase in the blood colloidal osmotic pressure, which helps to retain water in the bloodstream. Lastly, increasing water intake is another way the body defends blood volume against dehydration. Therefore, all of the above options are correct explanations for how the body defends blood volume against dehydration.

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  • 38. 

    Most of the middle layer in the heart wall is composed of

    • Cardiac muscle cells.

    • Chondrocytes.

    • Epitheliocytes.

    • Fibrocytes.

    • Smooth muscle cells.

    Correct Answer
    A. Cardiac muscle cells.
    Explanation
    The correct answer is cardiac muscle cells. The middle layer of the heart wall, known as the myocardium, is primarily composed of cardiac muscle cells. These cells are specialized for contraction and play a crucial role in pumping blood throughout the body. Unlike other types of muscle cells, such as smooth muscle cells, cardiac muscle cells have distinct striations and are interconnected by intercalated discs, allowing for coordinated contractions. Therefore, cardiac muscle cells are the main component of the middle layer of the heart wall.

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  • 39. 

    There are ________ pulmonary veins.

    • 2

    • 4

    • 6

    • 8

    • 10

    Correct Answer
    A. 4
    Explanation
    There are four pulmonary veins.

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  • 40. 

    When the left ventricle contracts, the distance from the apex to the base

    • Increases.

    • Decreases.

    • Remains unchanged.

    Correct Answer
    A. Decreases.
    Explanation
    When the left ventricle contracts, the distance from the apex to the base decreases. This is because during contraction, the ventricle pushes the blood out of the heart and into the aorta, which causes the walls of the ventricle to come closer together. As a result, the distance from the apex (the bottom of the heart) to the base (the top of the heart) decreases.

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  • 41. 

    As a result of the long refractory period in the cardiac action potential, cardiac muscle cannot exhibit

    • Tonus.

    • Treppe.

    • Tetany.

    • Recruitment.

    • Fatigue.

    Correct Answer
    A. Tetany.
    Explanation
    The long refractory period in the cardiac action potential refers to the period of time after a cardiac muscle cell has depolarized and cannot be stimulated again. This prevents the muscle from entering a state of tetany, which is a sustained and continuous contraction of the muscle. Tetany occurs when the muscle is repeatedly stimulated before it has a chance to fully relax. Therefore, due to the long refractory period, cardiac muscle cannot exhibit tetany.

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  • 42. 

    Which of the following would be greater?

    • The end-diastolic volume when the heart rate is 150 beats/minute

    • The end-diastolic volume when the heart rate is 60 beats/minute

    Correct Answer
    A. The end-diastolic volume when the heart rate is 60 beats/minute
    Explanation
    The end-diastolic volume refers to the amount of blood in the ventricles at the end of diastole, which is the relaxation phase of the cardiac cycle. When the heart rate is higher at 150 beats/minute, the ventricles have less time to fill with blood during diastole, resulting in a smaller end-diastolic volume. Conversely, when the heart rate is lower at 60 beats/minute, the ventricles have more time to fill with blood, leading to a larger end-diastolic volume.

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  • 43. 

    Averaged over a few heartbeats, venous return is ________ cardiac output.

    • Much higher than

    • Somewhat higher than

    • Equal to

    • Somewhat lower than

    • Much lower than

    Correct Answer
    A. Equal to
    Explanation
    The statement suggests that venous return, when averaged over a few heartbeats, is equal to cardiac output. This means that the amount of blood returning to the heart through the veins is the same as the amount of blood being pumped out of the heart.

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  • 44. 

    Blood pressure increases with all of the following, except increased

    • Cardiac output.

    • Peripheral resistance.

    • Blood volume.

    • Parasympathetic innervation.

    • Force of cardiac contraction.

    Correct Answer
    A. Parasympathetic innervation.
    Explanation
    Blood pressure is primarily regulated by two factors: cardiac output and peripheral resistance. When cardiac output increases, the heart pumps more blood into the arteries, leading to an increase in blood pressure. Similarly, when peripheral resistance increases, the blood vessels constrict, causing an increase in blood pressure. Additionally, an increase in blood volume can also contribute to elevated blood pressure. However, parasympathetic innervation, which is responsible for regulating the body's rest and digest functions, does not directly affect blood pressure. Therefore, the correct answer is parasympathetic innervation.

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  • 45. 

    In response to hemorrhage, there is

    • Peripheral vasoconstriction.

    • Increased sympathetic stimulation of the heart.

    • Mobilization of the venous reserve.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    In response to hemorrhage, the body undergoes several physiological changes to compensate for the loss of blood. Peripheral vasoconstriction occurs to redirect blood flow to vital organs. There is also increased sympathetic stimulation of the heart, which leads to an increased heart rate and cardiac output. Additionally, the body mobilizes the venous reserve, releasing stored blood from the veins into circulation. Therefore, all of the given options are correct as they describe the various responses to hemorrhage.

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  • 46. 

    The interventricular sulci and coronary sulcus contain

    • Fat.

    • Arteries.

    • Veins.

    • All of the above

    • None of the above

    Correct Answer
    A. All of the above
    Explanation
    The interventricular sulci and coronary sulcus contain fat, arteries, and veins. The interventricular sulci are grooves on the surface of the heart that separate the left and right ventricles. These sulci contain fat, which helps to protect and cushion the heart. The coronary sulcus is a groove that encircles the heart and contains the coronary arteries and veins, which supply blood to the heart muscle. Therefore, all of the given options, including fat, arteries, and veins, are present in the interventricular sulci and coronary sulcus.

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  • 47. 

    The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the

    • Atrial systole.

    • Early diastolic filling phase.

    • Late diastolic filling phase.

    • Ventricular ejection of the ventricular systole.

    • Dicrotic phase.

    Correct Answer
    A. Ventricular ejection of the ventricular systole.
    Explanation
    During the ventricular ejection phase of the cardiac cycle, the mitral valve is closed to prevent blood from flowing back into the atrium, while the aortic valve is open to allow blood to be ejected from the left ventricle into the aorta. This phase occurs during ventricular systole, which is the contraction of the ventricles.

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  • 48. 

    The volume of blood ejected from each ventricle during a contraction is called the

    • End-diastolic volume.

    • End-systolic volume.

    • Stroke volume.

    • Cardiac output.

    • Cardiac reserve.

    Correct Answer
    A. Stroke volume.
    Explanation
    The volume of blood ejected from each ventricle during a contraction is called the stroke volume. This is the amount of blood that is pumped out of the heart with each heartbeat. It is calculated by subtracting the end-systolic volume (the amount of blood left in the ventricle after contraction) from the end-diastolic volume (the amount of blood in the ventricle before contraction). The stroke volume is an important measure of heart function and can be used to calculate the cardiac output, which is the amount of blood pumped by the heart in one minute.

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  • 49. 

    Which of the following would increase heart rate?

    • Increased sympathetic stimulation of SA node

    • Decreased parasympathetic stimulation of nodal fibers

    • Increased levels of norepinephrine and/or epinephrine

    • Faster depolarization of the pacemaker potential

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    All of the options listed would increase heart rate. Increased sympathetic stimulation of the SA node leads to increased heart rate as it increases the firing rate of the SA node, which is responsible for initiating the electrical impulses that regulate the heart's rhythm. Decreased parasympathetic stimulation of nodal fibers also increases heart rate, as the parasympathetic nervous system slows down heart rate. Increased levels of norepinephrine and/or epinephrine, which are released during stress or exercise, increase heart rate by binding to receptors in the heart and increasing the strength and frequency of contractions. Faster depolarization of the pacemaker potential also leads to an increased heart rate.

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Quiz Review Timeline (Updated): Mar 22, 2023 +

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  • Current Version
  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Jun 12, 2013
    Quiz Created by
    Seres21e

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