Chapter 17: Function Of The Heart

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  • 1/577 Questions

    Which of the following is descriptive of the vagus nerve?

    • "fight or flight"
    • Parasympathetic
    • Sympathetic
    • Adrenergic
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Chapter 17: Function Of The Heart - Quiz
About This Quiz

Explore the key functions of the heart in 'Chapter 17: Function of the Heart'. This quiz assesses understanding of myocardial activities, phases of heart cycles, and the effects of various conditions on heart function. Essential for students and professionals in medical and health-related fields.

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  • 2. 

    Heart rate and stroke volume determine

    • Hemotocrit

    • Total blood volume

    • Cardiac output

    • The size of the heart valves

    Correct Answer
    A. Cardiac output
    Explanation
    Heart rate and stroke volume are two important factors that determine cardiac output. Heart rate refers to the number of times the heart beats per minute, while stroke volume refers to the amount of blood pumped out of the heart with each beat. Cardiac output is the total volume of blood pumped by the heart in one minute, and it is calculated by multiplying the heart rate by the stroke volume. Therefore, heart rate and stroke volume directly affect cardiac output.

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  • 3. 

    This term refers to a heart rate of fewer that 60 beats/min

    • Bradycardia

    • Heart block

    • Fight-or-flight response

    • Tachycardia

    Correct Answer
    A. Bradycardia
    Explanation
    Bradycardia refers to a heart rate of fewer than 60 beats per minute. This condition occurs when the heart beats slower than normal, which can be caused by various factors such as certain medications, heart disease, or an imbalance in the electrical signals that control the heart. Bradycardia can lead to symptoms like dizziness, fatigue, and shortness of breath. Treatment options may include medication, pacemaker implantation, or addressing the underlying cause of the condition.

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  • 4. 

    Vagal stimulation on the heart

    • Increases the force of myocardial contraction

    • Increases the amount of blood that flows into the heart from the vena cava

    • Causes tachycardia

    • Slows the heart rate

    Correct Answer
    A. Slows the heart rate
    Explanation
    Vagal stimulation on the heart slows the heart rate. The vagus nerve, also known as the parasympathetic nervous system, is responsible for regulating the heart rate. When the vagus nerve is stimulated, it releases acetylcholine, which slows down the electrical conduction in the heart and decreases the heart rate. This is known as vagal bradycardia.

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  • 5. 

    Which of the following most accurately describes the vagus nerve?

    • "fight or flight"

    • Norepinephrine

    • Parasympathetic

    • Causes tachycardia

    Correct Answer
    A. Parasympathetic
    Explanation
    The vagus nerve is a part of the parasympathetic nervous system. It is responsible for regulating various bodily functions such as heart rate, digestion, and breathing. Unlike the "fight or flight" response associated with the sympathetic nervous system, the vagus nerve promotes a calming and relaxing effect on the body. Therefore, the answer "parasympathetic" accurately describes the vagus nerve's role in the body.

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  • 6. 

    What is the term for the sequence of events that occur during one heartbeat?

    • Stroke volume

    • Cardiac output

    • Cardiac cycle

    • Systole

    Correct Answer
    A. Cardiac cycle
    Explanation
    The term for the sequence of events that occur during one heartbeat is called the cardiac cycle. This includes the contraction and relaxation of the heart chambers, as well as the opening and closing of the heart valves. The cardiac cycle is responsible for pumping blood throughout the body and ensuring proper circulation.

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  • 7. 

      The cardiovascular center is located

    • In the thorax

    • In the cerebral cortex

    • In the cerebellum

    • In the medulla oblongata

    • In the hypothalamus

    Correct Answer
    A. In the medulla oblongata
    Explanation
    The cardiovascular center is located in the medulla oblongata. This region of the brain is responsible for regulating and controlling many vital functions of the cardiovascular system, including heart rate, blood pressure, and blood vessel constriction. It receives sensory input from baroreceptors and chemoreceptors, and then sends signals to the heart and blood vessels to adjust their activity accordingly. The medulla oblongata plays a crucial role in maintaining homeostasis and ensuring proper functioning of the cardiovascular system.

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  • 8. 

      This type of shock is due to decreased blood volume.

    • Hypovolemic

    • Cardiogenic

    • Vascular

    • Obstructive

    • Neurogenic

    Correct Answer
    A. Hypovolemic
    Explanation
    Hypovolemic shock occurs when there is a significant decrease in blood volume, leading to inadequate perfusion of organs and tissues. This can be caused by factors such as severe bleeding, dehydration, or fluid loss from burns. The decreased blood volume results in decreased cardiac output and tissue oxygenation, leading to symptoms such as low blood pressure, rapid heart rate, and altered mental status. Treatment involves addressing the underlying cause of the fluid loss and restoring blood volume through intravenous fluids or blood transfusions.

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  • 9. 

      What do the following have in common: superficial temporal artery, brachial artery and dorsal artery of the foot?

    • They are all areas where you can not hear Korotkoff sounds

    • They are all only found on the left side of the body

    • They are all pulse points

    • None of them contain baroreceptors

    • All of the are connected to each other by capillary beds

    Correct Answer
    A. They are all pulse points
    Explanation
    The correct answer is that they are all pulse points. Pulse points are specific areas in the body where arteries are close to the skin's surface, making it easier to feel the pulse. The superficial temporal artery, brachial artery, and dorsal artery of the foot are all examples of pulse points.

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  • 10. 

    What happens during ventricular diastole?

    • The ventricles are filling with blood

    • All semilunar valves are open

    • Both AV valves are closed

    • Blood is pumped to the lungs and systemic circulation

    Correct Answer
    A. The ventricles are filling with blood
    Explanation
    During ventricular diastole, the ventricles of the heart are relaxed and filling with blood. This is the phase of the cardiac cycle when the heart is at rest and preparing for the next contraction. Both atrioventricular (AV) valves, which separate the atria from the ventricles, are closed to prevent blood from flowing back into the atria. The semilunar valves, which separate the ventricles from the arteries, are also closed during this phase. Blood is not being pumped to the lungs or systemic circulation during ventricular diastole, as that occurs during ventricular systole.

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  • 11. 

    Which term refers to the amount of blood pumped by the heart in one minute?

    • Stroke volume

    • Cardiac output

    • Starling's law of the heart

    • Inotropic effect

    Correct Answer
    A. Cardiac output
    Explanation
    Cardiac output refers to the amount of blood pumped by the heart in one minute. It is a measure of the heart's efficiency in delivering oxygenated blood to the body's tissues. Cardiac output is calculated by multiplying the heart rate (number of beats per minute) by the stroke volume (amount of blood pumped with each beat). It is an important parameter in assessing cardiovascular health and can be influenced by various factors such as exercise, stress, and certain medical conditions.

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  • 12. 

    Excess vagal stimulation to the SA node is most likely to cause

    • Hypertension

    • Bradycardia

    • Tachycardia

    • Anemia

    Correct Answer
    A. Bradycardia
    Explanation
    Excess vagal stimulation to the SA node can cause bradycardia. The vagus nerve, which is part of the parasympathetic nervous system, innervates the SA node and slows down the heart rate. When there is excessive stimulation of the vagus nerve, it can lead to a decrease in heart rate, resulting in bradycardia. This can happen in certain medical conditions or due to certain medications that increase vagal tone. Hypertension, tachycardia, and anemia are not directly caused by excess vagal stimulation to the SA node.

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  • 13. 

    Systole and diastole describe the function of the

    • Pericardium

    • SA node

    • Myocardium

    • Mediastinum

    Correct Answer
    A. Myocardium
    Explanation
    Systole and diastole refer to the contraction and relaxation of the heart, respectively. The myocardium is the muscular tissue of the heart responsible for these actions. It contracts during systole to pump blood out of the heart and relaxes during diastole to allow the chambers to fill with blood. Therefore, the myocardium is directly involved in the function of systole and diastole.

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  • 14. 

    Which of the following is the most likely consequence of a very rapid heart rate?

    • Decreased ventricular filling (with blood)

    • Failure of the AV valves to open

    • Failure of the SA node to fire

    Correct Answer
    A. Decreased ventricular filling (with blood)
    Explanation
    A very rapid heart rate can lead to decreased ventricular filling with blood because when the heart beats too quickly, there is not enough time for the ventricles to fully fill with blood before the next contraction. This can result in a decrease in the amount of blood pumped out of the heart with each beat, leading to a decreased cardiac output.

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  • 15. 

    Which of the following is most likely to relieve an anxiety-induced tachycardia?

    • Vagolytic drug

    • Beta1 adrenergic agonist

    • Sympathomimetic

    • Beta1 adrenergic blocker

    Correct Answer
    A. Beta1 adrenergic blocker
    Explanation
    A beta1 adrenergic blocker is most likely to relieve an anxiety-induced tachycardia. Tachycardia refers to a rapid heartbeat, and anxiety can often cause an increase in heart rate. Beta1 adrenergic blockers, also known as beta blockers, work by blocking the effects of adrenaline on the beta1 receptors in the heart. By doing so, they can reduce the heart rate and blood pressure, helping to relieve tachycardia.

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  • 16. 

    Which of the following is responsible for the Starling effect?

    • Sympathetic nerve firing

    • Vagal discharge

    • Activation of the beta1 adrenergic receptors

    • End diastolic volume (EDV)

    Correct Answer
    A. End diastolic volume (EDV)
    Explanation
    The Starling effect refers to the phenomenon where an increase in end diastolic volume (EDV) results in a more forceful contraction of the heart and an increase in stroke volume. EDV is the volume of blood in the ventricles at the end of diastole, just before contraction. As the ventricles fill with more blood, the myocardial fibers are stretched, leading to a more forceful contraction and an increased stroke volume. This effect allows the heart to adapt and pump a greater volume of blood when there is an increase in venous return or preload.

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  • 17. 

    Which of the following is most likely to increase stroke volume?

    • A (+) inotrpic drug

    • A vagolytic drug

    • A (-) chronotropic drug

    • A beta1 adrenergic blocker

    Correct Answer
    A. A (+) inotrpic drug
    Explanation
    A (+) inotropic drug is most likely to increase stroke volume. Inotropic drugs enhance the force of contraction of the heart muscle, leading to an increase in the amount of blood pumped out of the heart with each heartbeat. This increased force of contraction results in an increased stroke volume, which is the amount of blood ejected from the heart per beat. Therefore, a (+) inotropic drug would be expected to increase stroke volume.

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  • 18. 

    Sympathetic nerve stimulation of the myocardium

    • Causes a (+) inotropic effect

    • Decreases cardiac output

    • Decreases heart rate

    • Decreases stroke volume

    Correct Answer
    A. Causes a (+) inotropic effect
    Explanation
    Sympathetic nerve stimulation of the myocardium causes a (+) inotropic effect. This means that it increases the force of contraction of the heart muscle. When the sympathetic nervous system is activated, it releases norepinephrine, which binds to beta-adrenergic receptors on the myocardium. This leads to an increase in intracellular calcium levels, which in turn enhances the contractility of the heart. As a result, the heart pumps blood more forcefully, leading to an increase in the strength of the heartbeat.

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  • 19. 

    A drug (i.e., atropine) that blocks the vagus nerve

    • Stops the heart

    • Increases the heart rate

    • Decreases cardiac output

    • Decreases stroke volume

    Correct Answer
    A. Increases the heart rate
    Explanation
    Atropine is a drug that blocks the vagus nerve, which is responsible for slowing down the heart rate. By blocking the vagus nerve, atropine prevents its inhibitory effect on the heart, leading to an increase in heart rate. Therefore, the correct answer is that atropine increases the heart rate.

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  • 20. 

    Decreased blood flow through the coronary arteries is most likely to cause

    • Valve damage

    • Pulmonary edema

    • Angina pectoris

    • Bradycardia

    Correct Answer
    A. Angina pectoris
    Explanation
    Decreased blood flow through the coronary arteries can lead to a reduced supply of oxygen and nutrients to the heart muscle. This can cause chest pain known as angina pectoris. Angina occurs when the heart does not receive enough blood and oxygen to meet its demands, usually during physical activity or periods of emotional stress. It is characterized by a squeezing or pressure-like sensation in the chest, which may radiate to the arms, neck, jaw, or back. Angina pectoris is a common symptom of coronary artery disease, where the arteries that supply blood to the heart become narrowed or blocked.

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  • 21. 

    During atrial systole, the

    • AV valves are closed

    • Ventricles are relaxed

    • Ventricles are in systole

    • Semilunar valves are open

    Correct Answer
    A. Ventricles are relaxed
    Explanation
    During atrial systole, the atria contract to push blood into the ventricles. At this stage, the AV valves (tricuspid and mitral valves) are closed to prevent the backflow of blood from the ventricles to the atria. The ventricles are relaxed during this phase, as they have already pumped blood out during the previous ventricular systole. The semilunar valves (pulmonary and aortic valves) are closed at this stage to prevent blood from flowing back into the ventricles. Therefore, the correct answer is "ventricles are relaxed".

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  • 22. 

    Which of the following does not happen to a ventricle?

    • Activation of the beta1 adrenergic receptors

    • Discharge of sympathetic nerves

    • Discharge of the vagal nerve

    • Binding of norepinephrine to its receptor

    Correct Answer
    A. Discharge of the vagal nerve
    Explanation
    The discharge of the vagal nerve does not happen to a ventricle. The vagal nerve, also known as the parasympathetic nerve, is responsible for slowing down the heart rate and reducing the force of contractions. In contrast, the other options mentioned, such as activation of beta1 adrenergic receptors, discharge of sympathetic nerves, and binding of norepinephrine to its receptor, all involve sympathetic activation, which increases heart rate and contractility.

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  • 23. 

    Which of the following is the same as end dialostic volume?

    • Stroke volume

    • Cardiac output

    • Preload

    • Cardiac reserve

    Correct Answer
    A. Preload
    Explanation
    Preload refers to the volume of blood in the ventricles at the end of diastole, just before contraction. It represents the amount of blood that the heart has to pump out with each beat. End diastolic volume is the same as preload because it refers to the volume of blood in the ventricles at the end of diastole. Therefore, preload is the correct answer.

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  • 24. 

      Which of the below would NOT increase blood pressure.

    • Increased blood volume

    • Increased sympathetic stimulation

    • Increased heart rate

    • Increased stroke volume

    • Decreased cardiac output

    Correct Answer
    A. Decreased cardiac output
    Explanation
    A decreased cardiac output would not increase blood pressure because cardiac output is the amount of blood pumped by the heart per minute. If the cardiac output decreases, there is less blood being pumped into the arteries, resulting in lower blood pressure. Therefore, a decrease in cardiac output would not contribute to an increase in blood pressure.

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  • 25. 

      Which of the below factors do NOT increase systemic vascular resistance?

    • Decreased vessel lumen diameter

    • Increased blood viscosity

    • Decreased vessel length

    • Increased vasodilation

    • Increased blood cell count

    Correct Answer
    A. Decreased vessel length
    Explanation
    A decrease in vessel length does not increase systemic vascular resistance because resistance is directly proportional to vessel length. When vessel length decreases, the resistance to blood flow decreases as well. This is because shorter vessels offer less resistance to the flow of blood compared to longer vessels. Therefore, a decrease in vessel length would not contribute to an increase in systemic vascular resistance.

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  • 26. 

      This depends mostly on the ratio of RBC to plasma volume.

    • Total blood volume

    • Blood viscosity

    • Systemic resistance

    • Blood vessel length

    • Size of vessel lumen

    Correct Answer
    A. Blood viscosity
    Explanation
    Blood viscosity refers to the thickness or stickiness of blood. It is determined by the concentration of red blood cells and plasma proteins in the blood. Higher viscosity means the blood is thicker and flows more slowly, while lower viscosity means the blood is thinner and flows more easily. The explanation for blood viscosity being the correct answer is that it is a factor that affects the flow of blood through the blood vessels. Higher viscosity can increase resistance to blood flow, leading to decreased circulation and potential cardiovascular problems.

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  • 27. 

      Where can pulse not be felt?

    • Arteries

    • Veins

    • Venules

    • Capillaries

    • Arterioles

    Correct Answer
    A. Capillaries
    Explanation
    Capillaries are the smallest blood vessels in the body and their walls are very thin, allowing for the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues. Due to their small size and thin walls, the pulse cannot be felt in capillaries. The pulse is typically felt in larger blood vessels such as arteries and arterioles, where the pressure from the heartbeat can be detected. Veins, venules, and capillaries do not have the same level of pressure and elasticity as arteries, making it difficult to feel the pulse in these blood vessels.

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  • 28. 

      In fetal circulation what is the opening between the right and left atria called?

    • Ductus venosus

    • Umbilicus

    • Umbilical vein

    • Foramen ovale

    • Placenta

    Correct Answer
    A. Foramen ovale
    Explanation
    The opening between the right and left atria in fetal circulation is called the foramen ovale. This opening allows blood to bypass the lungs and flow directly from the right atrium to the left atrium. After birth, the foramen ovale usually closes, redirecting blood flow to the lungs for oxygenation.

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  • 29. 

      Which of the below vessels is a pulse point at the wrist?

    • Radial artery

    • Subclavian artery

    • Axillary artery

    • Cephalic artery

    • Palmar artery

    Correct Answer
    A. Radial artery
    Explanation
    The radial artery is a pulse point at the wrist. This artery is located on the thumb side of the wrist and is commonly used to measure the pulse rate. It is easily accessible and its pulsations can be felt by placing two fingers on the wrist. The other options listed are not pulse points at the wrist.

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  • 30. 

    This heart structure(s) carries deoxygenated blood.

    • Left atrium and ventricle

    • Left atrium only

    • Right ventricle only

    • Right atrium and ventricle

    • Left atrium and right ventricle

    Correct Answer
    A. Right atrium and ventricle
    Explanation
    The right atrium and ventricle carry deoxygenated blood. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava. It then pumps this blood into the right ventricle, which further pumps it to the lungs for oxygenation.

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  • 31. 

    Cardiac muscle fibers electrically connect to neighboring fibers by

    • Intermediate discs

    • Gap junctions

    • Contractile fibers

    • Chordae tendinae

    • Desmosomes

    Correct Answer
    A. Gap junctions
    Explanation
    Cardiac muscle fibers electrically connect to neighboring fibers through gap junctions. Gap junctions are specialized protein channels that allow for the direct passage of ions and small molecules between cells. These junctions facilitate the rapid and synchronized contraction of the cardiac muscle, ensuring efficient pumping of blood. Intermediate discs, contractile fibers, chordae tendinae, and desmosomes are not involved in the electrical connection between cardiac muscle fibers.

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  • 32. 

    This is a the correct sequence of structures that allows the normal sequence of excitation to progress through the heart.

    • Bundle of His, SA node, AV node, Purkinje fibers

    • Sinoatrial (SA), Purkinje fibers, AV node, Bundle of His

    • Purkinje fibers, AV node, SA node, Bundle of His

    • SA node, AV node, Bundle of His, Purkinje fibers

    • Bundle of His, Purkinje fibers, Atrioventricular (AV) node

    Correct Answer
    A. SA node, AV node, Bundle of His, Purkinje fibers
    Explanation
    The correct answer is SA node, AV node, Bundle of His, Purkinje fibers. This sequence follows the normal pathway of electrical conduction in the heart. The SA node, located in the right atrium, initiates the electrical impulse. The impulse then travels to the AV node, located between the atria and ventricles, where it is delayed to allow for atrial contraction before passing to the Bundle of His. The Bundle of His then divides into the left and right bundle branches, which carry the impulse to the Purkinje fibers, allowing for coordinated ventricular contraction.

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  • 33. 

    This term refers to the period of time during a cardiac cycle when contraction occurs and blood pressure rises.

    • Systole

    • Repolarization

    • Fibrillation

    • Filling

    • Diastole

    Correct Answer
    A. Systole
    Explanation
    Systole refers to the period of time during a cardiac cycle when contraction occurs and blood pressure rises. This is the phase where the heart muscles contract, pushing blood out of the chambers and into the arteries. During systole, the ventricles contract, the atrioventricular valves close, and the semilunar valves open, allowing blood to be pumped out of the heart. This phase is crucial for maintaining blood flow and delivering oxygen and nutrients to the body's tissues.

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  • 34. 

    The second heart sound (dupp) closely follows which of the events listed below.

    • Semilunar valves opening

    • Atrioventricular valves opening

    • Atrioventricular valves closing

    • Semilunar valves closing

    • Valvular stenosis

    Correct Answer
    A. Semilunar valves closing
    Explanation
    The second heart sound (dupp) closely follows the closing of the semilunar valves. This sound occurs when the aortic and pulmonary valves close at the end of ventricular systole, preventing the backflow of blood into the ventricles. The closure of these valves produces a characteristic sound that can be heard during a cardiac examination.

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  • 35. 

    Which of the below reduces heart rate.

    • Increased sympathetic stimulation

    • Increased Norepinephrine hormone

    • Increased Thyroid hormone

    • Increased calcium levels

    • Increased potassium levels

    Correct Answer
    A. Increased potassium levels
    Explanation
    Increased potassium levels can reduce heart rate because potassium is an electrolyte that plays a crucial role in regulating the electrical activity of the heart. Potassium helps maintain the resting membrane potential of cardiac cells, allowing them to repolarize after each contraction. When potassium levels are increased, it enhances the repolarization process, leading to a longer duration between heartbeats and ultimately reducing the heart rate.

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  • 36. 

    This part of the brain contains the cardiovascular center that regulates heart rate.

    • Medulla oblongata

    • Thalamus

    • Cerebellum

    • Midbrain

    • Cerebrum

    Correct Answer
    A. Medulla oblongata
    Explanation
    The medulla oblongata is the correct answer because it is a part of the brain that contains the cardiovascular center. This center is responsible for regulating heart rate, among other cardiovascular functions. The medulla oblongata is located at the base of the brainstem and plays a crucial role in maintaining vital bodily functions such as breathing, blood pressure, and heart rate.

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  • 37. 
    Which of the structures in the diagram below represent semilunar valves? - ProProfs

    Which of the structures in the diagram below represent semilunar valves?

    • B

    • D

    • E

    • A & C

    • NONE OF THE ABOVE

    Correct Answer
    A. A & C
    Explanation
    The correct answer is A & C because in the diagram, structures A and C are shown as valves located at the base of the aorta and pulmonary artery respectively. These valves are known as semilunar valves because of their half-moon shape. They function to prevent the backflow of blood into the ventricles during ventricular relaxation.

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  • 38. 
    The structure indicated is the - ProProfs

    The structure indicated is the

    • Epicardium.

    • Fibrous pericardium.

    • Myocardium.

    • Endocardium.

    • Parietal layer of the serous pericardium.

    Correct Answer
    A. Endocardium.
    Explanation
    The endocardium is the correct answer because it is the innermost layer of the heart wall. It is composed of endothelial cells and connective tissue. The epicardium is the outermost layer, the fibrous pericardium is the tough outer layer that surrounds the heart, the myocardium is the middle layer responsible for the contraction of the heart, and the parietal layer of the serous pericardium is the outer layer of the pericardium.

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  • 39. 

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

    • Activation of beta1 adrenergic receptors

    • Vagal discharge

    • Blockade of beta1 adrenergic receptors

    • Blockade of the muscarinic receptors

    Correct Answer
    A. Activation of beta1 adrenergic receptors
    Explanation
    Activation of beta1 adrenergic receptors is most likely to increase ejection fraction. Beta1 adrenergic receptors are primarily found in the heart and their activation leads to an increase in heart rate and contractility. This increased contractility allows for a larger volume of blood to be pumped out of the heart with each contraction, leading to an increase in ejection fraction.

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  • 40. 

    What terms refers to the amount of blood pumped by the ventricle in one boat?

    • Cardiac output

    • Blood volume

    • Hematocrit

    • Stroke volume

    Correct Answer
    A. Stroke volume
    Explanation
    Stroke volume refers to the amount of blood pumped by the ventricle in one beat. It is a measure of the volume of blood ejected from the heart with each contraction of the ventricles. Cardiac output, on the other hand, refers to the total amount of blood pumped by the ventricle in one minute and is calculated by multiplying stroke volume by heart rate. Blood volume refers to the total volume of blood in the body, and hematocrit is the percentage of red blood cells in the blood.

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  • 41. 

    Vagal stimulation to the heart causes

    • A (+) inotrpoic effect

    • Heart rate to slow

    • Cardiac output to increase

    • Stroke volume to increase

    Correct Answer
    A. Heart rate to slow
    Explanation
    Vagal stimulation to the heart activates the parasympathetic nervous system, specifically the vagus nerve. This stimulation leads to a decrease in heart rate, as the vagus nerve releases acetylcholine, which slows down the firing rate of the sinoatrial (SA) node, the natural pacemaker of the heart. Therefore, the correct answer is "heart rate to slow."

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  • 42. 

    Activation of the muscarinic receptors by acetylcholine

    • Increases myocardial contractile force

    • Causes a (+) chronotropic effect

    • Increases cardiac output

    • Slows heart rate

    Correct Answer
    A. Slows heart rate
    Explanation
    Activation of muscarinic receptors by acetylcholine slows heart rate. Muscarinic receptors are found in the parasympathetic nervous system, which is responsible for regulating the heart rate. When these receptors are activated, it leads to a decrease in heart rate, known as a negative chronotropic effect. This is due to the inhibitory actions of the parasympathetic nervous system on the heart, which helps to balance the sympathetic nervous system's stimulatory effects. Therefore, the correct answer is that activation of muscarinic receptors by acetylcholine slows heart rate.

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  • 43. 

    Which of the following contains 70ml?

    • The cardiac output

    • The volume of a ventricle

    • An average stroke volume

    • The amount of blood that flows through the pulmonary capillaries in one minute

    Correct Answer
    A. An average stroke volume
    Explanation
    An average stroke volume refers to the amount of blood pumped out of the heart by a ventricle with each contraction. Therefore, it makes sense that an average stroke volume would contain a specific volume of blood, in this case, 70ml.

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  • 44. 

      Circulation time

    • Varies with diet

    • Is set by the hypothalamus

    • In a resting person is normally 1 minute

    • Depends on hormones from the liver

    • Will stop a heart if it is lower than 20 seconds

    Correct Answer
    A. In a resting person is normally 1 minute
    Explanation
    The correct answer is "in a resting person is normally 1 minute." This means that in a person who is at rest, the time it takes for blood to circulate throughout the body is typically around 1 minute. This is a normal and healthy circulation time for someone who is not engaged in physical activity.

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  • 45. 

      Which of the below factors is most important in forcing blood flow through veins?

    • Heart rate

    • Stroke volume

    • Muscular activity

    • Blood velocity

    • Valve opening

    Correct Answer
    A. Muscular activity
    Explanation
    Muscular activity is the most important factor in forcing blood flow through veins. When muscles contract and relax, they squeeze the veins and help push the blood towards the heart. This action is particularly important in the legs, where the muscles act as a pump to overcome gravity and prevent blood from pooling in the lower extremities. Muscular activity also helps to maintain venous return, which is the flow of blood back to the heart. Without sufficient muscular activity, blood flow through the veins would be compromised, leading to various circulatory problems.

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  • 46. 

    Which of the below would be the response of the body as a result of decreased frequency of action potentials arising from the baroreceptors?

    • Increased blood pressure

    • Increased parasympathetic stimulation

    • Decreased heart rate

    • Decreased stroke volume

    • Decreased cardiac output

    Correct Answer
    A. Increased blood pressure
    Explanation
    A decreased frequency of action potentials from the baroreceptors would result in a decrease in the inhibitory signals sent to the brain, leading to a decrease in parasympathetic stimulation and an increase in sympathetic stimulation. This would cause an increase in heart rate, stroke volume, and cardiac output, leading to increased blood pressure.

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  • 47. 

      Which of the following hormones would NOT cause an increase in blood pressure?

    • Atrial Natriuretic Peptide

    • Antidiuretic Hormone

    • Aldosterone

    • Angiotensin

    • Increased Norepinephrine

    Correct Answer
    A. Atrial Natriuretic Peptide
    Explanation
    Atrial Natriuretic Peptide is a hormone that is released by the heart in response to high blood pressure. Its main function is to promote the excretion of sodium and water by the kidneys, which leads to a decrease in blood volume and subsequently lowers blood pressure. Therefore, Atrial Natriuretic Peptide would not cause an increase in blood pressure.

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  • 48. 

      Chemoreceptors in blood vessels measuring high levels of blood carbon dioxide would NOT cause which of the following

    • Increased heart rate

    • Increased vasoconstriction of blood vessels

    • Increased blood pressure

    • Decreased respiratory rate

    • Decreased heart rate

    Correct Answer
    A. Decreased respiratory rate
    Explanation
    Chemoreceptors in blood vessels measure the levels of carbon dioxide in the blood. When they detect high levels of carbon dioxide, they send signals to the brain to increase the respiratory rate, which means the person breathes faster to eliminate the excess carbon dioxide. Therefore, the correct answer is "Decreased respiratory rate" because chemoreceptors would not cause a decrease in breathing rate when they sense high levels of carbon dioxide.

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  • 49. 

      The myogenic response make smooth muscle

    • Contract more forcefully when stretched

    • Contract more forcefully when relaxed

    • Stay in an isotonic state

    • Less elastic

    • More elastic

    Correct Answer
    A. Contract more forcefully when stretched
    Explanation
    The myogenic response refers to the ability of smooth muscle to contract more forcefully when it is stretched. This response is an important mechanism for regulating blood flow and maintaining blood pressure in various organs and tissues. When smooth muscle is stretched, it responds by contracting more forcefully, which helps to prevent overstretching and maintain the appropriate level of tension. This response is particularly important in blood vessels, where it helps to regulate blood flow and ensure adequate perfusion to different tissues.

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Quiz Review Timeline (Updated): Mar 21, 2023 +

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  • Current Version
  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Oct 29, 2015
    Quiz Created by
    Kittykema

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