Guyton and Hall Physiology Chapter 21 - Muscle Blood Flow and Cardiac Output During Exercise
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Questions and Answers

What type of drug is commonly used to provide immediate relief during an acute anginal attack?

  • Beta blockers
  • Calcium channel blockers
  • Angiotensin receptor blockers
  • Vasodilators (correct)

    • What is a potential long-term consequence of angioplasty in patients treated for coronary artery blockages?

  • Restenosis of the artery (correct)
  • Decreased heart rate
  • Improved pumping capability
  • Increase in blood pressure

    • What do beta blockers prevent during exercise or emotional stress?

  • Sympathetic enhancement of heart rate (correct)
  • Calcium channel entry
  • Vasodilation of blood vessels
  • Angina pectoris occurrence

    • How does the pumping capability of a heart recovering from a large myocardial infarction typically compare to that of a healthy heart?

    <p>It is permanently decreased</p> Signup and view all the answers

    Which class of drugs is primarily used for the prolonged treatment of angina pectoris?

    <p>Beta blockers</p> Signup and view all the answers

    What primarily regulates blood flow to skeletal muscles during exercise?

    <p>Local control of vascular resistance</p> Signup and view all the answers

    What happens to muscle capillaries during strenuous exercise?

    <p>All capillaries open to enhance blood flow</p> Signup and view all the answers

    How does increased blood flow through capillaries affect muscle tissue?

    <p>It decreases nutrient diffusion distance</p> Signup and view all the answers

    What is the effect of decreased oxygen in muscles during exercise?

    <p>It enhances blood flow to the muscle</p> Signup and view all the answers

    What role does capillary surface area play during exercise?

    <p>It can increase twofold to threefold during exercise</p> Signup and view all the answers

    Which process contributes to rapid weakening of heart contractions during ischemia?

    <p>Reduced blood flow to the heart muscle</p> Signup and view all the answers

    What is a characteristic response of skeletal muscle to strenuous exercise?

    <p>Increased reliance on anaerobic metabolism</p> Signup and view all the answers

    How does the body cope with the large mass of skeletal muscle during exercise?

    <p>By increasing cardiac output and blood flow</p> Signup and view all the answers

    What physiological changes occur during exercise to increase cardiac output?

    <p>Sympathetic stimulation and muscle contraction</p> Signup and view all the answers

    What is the significance of the circulatory system's ability to increase cardiac output during exercise?

    <p>It helps deliver oxygen and nutrients to muscles</p> Signup and view all the answers

    How much can mean systemic filling pressure increase during maximal exercise?

    <p>From 7 mm Hg to 30 mm Hg</p> Signup and view all the answers

    What happens to resistance in blood vessels during heavy exercise?

    <p>Resistance decreases in virtually all blood vessels</p> Signup and view all the answers

    What is the relationship represented by the intersecting cardiac output and venous return curves during exercise?

    <p>They represent normal circulation and changes during exercise</p> Signup and view all the answers

    What effect do muscle contractions have on the capacitative parts of the circulation during exercise?

    <p>They compress internal vessels and increase filling pressure</p> Signup and view all the answers

    Why do marathon runners with the highest cardiac output tend to have record-breaking times?

    <p>They maintain a higher systemic filling pressure</p> Signup and view all the answers

    During exercise, what primarily causes the upward rotation of the venous return curve?

    <p>Decreased resistance in blood vessels of active muscles</p> Signup and view all the answers

    What happens to mean systemic filling pressure when venous return increases?

    <p>It increases proportionally</p> Signup and view all the answers

    Which of the following best describes the cardiac output change during heavy exercise?

    <p>Cardiac output increases significantly with exercise intensity</p> Signup and view all the answers

    What is the primary role of the left coronary artery?

    <p>Supplies mainly the anterior and left lateral portions of the left ventricle</p> Signup and view all the answers

    How much oxygen is typically removed from coronary arterial blood as it flows through the heart muscle?

    <p>70%</p> Signup and view all the answers

    What mainly regulates blood flow in the coronary arteries?

    <p>The oxygen demand of cardiac musculature</p> Signup and view all the answers

    Where does the cardiac muscle receive significant nutrition directly from blood?

    <p>From the inner one-tenth millimeter of the endocardial surface</p> Signup and view all the answers

    What area does the right coronary artery primarily supply?

    <p>Mostly the right ventricle and the posterior part of the left ventricle</p> Signup and view all the answers

    During which phase do coronary capillary blood flow in the left ventricle muscle significantly decrease?

    <p>Only during systole</p> Signup and view all the answers

    Which coronary arteries are depicted in the diagram of coronary vasculature?

    <p>Subendocardial, intramuscular, and epicardial coronary arteries</p> Signup and view all the answers

    What is the significance of the low oxygen levels after blood flows through the cardiac musculature?

    <p>It ensures the heart muscle doesn't require additional oxygen</p> Signup and view all the answers

    What determines the need for nutritional blood supply to the heart?

    <p>The relative deficiency of coronary blood supply</p> Signup and view all the answers

    In what percentage of the population does the right coronary artery supply the posterior part of the left ventricle?

    <p>80% to 90%</p> Signup and view all the answers

    What is the role of norepinephrine in the regulation of muscle blood flow?

    <p>It decreases blood flow through resting muscles.</p> Signup and view all the answers

    Which physiological response occurs in nonmuscular areas during muscle activity?

    <p>Blood flow decreases in nonmuscular areas.</p> Signup and view all the answers

    What is the potential effect of sympathetic vasoconstrictor nerves on blood flow during stress?

    <p>They can reduce blood flow in resting muscles to enhance blood supply to active muscles.</p> Signup and view all the answers

    What happens to blood flow in the coronary and cerebral systems during sympathetic activation?

    <p>They are spared from the vasoconstrictor effect.</p> Signup and view all the answers

    During intense exercise, how much additional blood flow may be provided to the muscles?

    <p>Up to 2 L/min.</p> Signup and view all the answers

    What happens to arterial pressure during physiological stress when sympathetic vasoconstriction is activated?

    <p>Arterial pressure may need to be increased.</p> Signup and view all the answers

    What primarily triggers vasodilation in active skeletal muscles?

    <p>Local vasodilator effects within the muscles.</p> Signup and view all the answers

    How much can blood flow through resting muscles decrease during maximal sympathetic activation?

    <p>To one-third of normal levels.</p> Signup and view all the answers

    What is the consequence of reduced blood flow in nonmuscular areas during muscle activity?

    <p>Enhanced blood supply to active muscles.</p> Signup and view all the answers

    What is the primary function of sympathetic vasodilator nerves, when present in some species?

    <p>To promote vasodilation in certain vascular beds.</p> Signup and view all the answers

    What causes blood vessels in muscles to relax during exercise?

    <p>Decreased levels of oxygen and release of vasodilators</p> Signup and view all the answers

    Which of the following factors continues to maintain increased capillary blood flow during prolonged exercise?

    <p>Vasodilating factors like lactic acid and carbon dioxide</p> Signup and view all the answers

    How does the body respond to the onset of exercise regarding heart function?

    <p>Increased heart rate and strength due to sympathetic stimulation</p> Signup and view all the answers

    What happens to blood flow between contractions during strong rhythmic muscle contraction?

    <p>Blood flow is less during contractions than between contractions</p> Signup and view all the answers

    Which statement about adenosine during exercise is true?

    <p>Adenosine's effects cannot sustain vasodilation after two hours of intense exercise.</p> Signup and view all the answers

    What is the role of norepinephrine in regulating blood flow during muscle activity?

    <p>It stimulates vasoconstriction in skeletal muscles.</p> Signup and view all the answers

    How much can blood flow through resting muscles decrease during maximal sympathetic activation?

    <p>It can reduce to one-third to one-half of normal.</p> Signup and view all the answers

    What occurs to blood flow in nonmuscular areas during the activation of sympathetic vasoconstrictor nerves?

    <p>Blood flow temporarily decreases to prioritize muscle blood flow.</p> Signup and view all the answers

    What physiological role does sympathetic vasoconstriction play during periods of stress?

    <p>It increases blood pressure by preserving arterial pressure.</p> Signup and view all the answers

    Which of the following statements is true regarding blood flow to the coronary and cerebral systems during sympathetic activation?

    <p>These areas are spared from the vasoconstrictor effects.</p> Signup and view all the answers

    What compensatory mechanism helps maintain blood flow during systole in the heart?

    <p>Subendocardial plexus activity</p> Signup and view all the answers

    Which of the following is NOT a vasodilator product identified in the coronary blood flow?

    <p>Lactic acid</p> Signup and view all the answers

    How long does the vascular dilation from adenosine infusion typically last?

    <p>1 to 3 hours</p> Signup and view all the answers

    What is the role of autonomic nerve stimulation in coronary blood flow?

    <p>It can affect blood flow directly and indirectly.</p> Signup and view all the answers

    What happens to the immediate blood flow in the subendocardial plexus during systole?

    <p>It tends to be reduced.</p> Signup and view all the answers

    Which of the following substances contributes to coronary vasodilation during increased cardiac activity?

    <p>Prostaglandins</p> Signup and view all the answers

    What primarily explains the peculiar difference in blood flow between epicardial and subendocardial arteries?

    <p>Muscle contraction effects</p> Signup and view all the answers

    What is the consequence of blocking vasodilator effects of adenosine?

    <p>Partial vasodilation is still observed</p> Signup and view all the answers

    Which mechanism is involved in coronary blood flow during periods of intense physical activity?

    <p>Increased metabolic demand</p> Signup and view all the answers

    What effect does the continued infusion of adenosine have on vascular dilation in muscle tissue?

    <p>Only temporary dilation</p> Signup and view all the answers

    Blood flow during strong rhythmic contraction is greater than between contractions.

    <p>False</p> Signup and view all the answers

    Adenosine is a significant vasodilator but cannot sustain increased blood flow in the skeletal muscle for more than about 2 hours during exercise.

    <p>True</p> Signup and view all the answers

    Lactic acid is one of the factors that help maintain increased capillary blood flow during prolonged exercise.

    <p>True</p> Signup and view all the answers

    Potassium ions do not play a role in maintaining increased blood flow during exercise.

    <p>False</p> Signup and view all the answers

    Sympathetic activation decreases heart rate during physical exertion.

    <p>False</p> Signup and view all the answers

    The right coronary artery primarily supplies the anterior part of the left ventricle.

    <p>False</p> Signup and view all the answers

    Most of the coronary venous blood flow from the left ventricular muscle returns to the right atrium by way of the coronary sinus.

    <p>True</p> Signup and view all the answers

    The right atrial pressure significantly changes during a strong heart's response to increased cardiac output.

    <p>False</p> Signup and view all the answers

    Coronary blood flow is higher during diastole than during systole.

    <p>True</p> Signup and view all the answers

    The left anterior descending branch is the most significant branch of the right coronary artery.

    <p>False</p> Signup and view all the answers

    Sympathetic stimulation typically causes coronary dilation.

    <p>False</p> Signup and view all the answers

    Ischemic heart disease is the leading cause of death in Western countries.

    <p>True</p> Signup and view all the answers

    Vasospastic myocardial ischemia during periods of excess sympathetic drive is common in all individuals.

    <p>False</p> Signup and view all the answers

    A significant percentage of people aged 65 and older in the United States die from ischemic heart disease.

    <p>True</p> Signup and view all the answers

    Acute coronary occlusion typically leads to slow death over years.

    <p>False</p> Signup and view all the answers

    Atherosclerosis is a significant cause of decreased coronary blood flow.

    <p>True</p> Signup and view all the answers

    The metabolic control of coronary flow can override nervous stimulation effects only after minutes.

    <p>False</p> Signup and view all the answers

    Genetic predisposition can influence the atherosclerotic process in cardiac muscle health.

    <p>True</p> Signup and view all the answers

    Myocardial oxygen consumption is not a major factor in controlling myocardial blood flow.

    <p>False</p> Signup and view all the answers

    Chapters 68 through 73 cover the basic principles of cellular metabolism as they apply to cardiac muscle.

    <p>True</p> Signup and view all the answers

    Match the coronary blood flow information with its corresponding value or statement:

    <p>Normal coronary blood flow at rest = 70 ml/min/100 g of heart weight Percentage of cardiac output for coronary blood flow = 4% to 5% Increase in cardiac output during strenuous exercise = 4-fold to 7-fold Increase in coronary blood flow during exercise = 3-fold to 4-fold</p> Signup and view all the answers

    Match the physiological impacts of exercise with their corresponding description:

    <p>Sympathetic stimulation during heavy exercise = Increased blood flow through the thebesian veins Marked increase in right atrial pressure = Occurs in patients with weakened hearts Work output increase under severe conditions = 6-fold to 9-fold Ratio of energy expenditure to blood flow = Increases during exercise</p> Signup and view all the answers

    Match the outcome of coronary artery disease with its likely demographic:

    <p>Coronary artery disease prevalence = Common in industrialized countries Older adults with coronary issues = Most have some impairment Main cause of mortality = One-third of all deaths in the Western world Understanding coronary circulation = Important for physicians</p> Signup and view all the answers

    Match the terms with their corresponding descriptions related to cardiac function:

    <p>Cardiac output during exercise = Pumps blood against higher arterial pressure Total cardiac output at rest = 225 ml/min Energy utilization efficiency during exercise = Increases Coronary blood flow during strenuous activity = May not be sufficient for energy needs</p> Signup and view all the answers

    Match the effects of exercise on the heart with their respective changes:

    <p>Cardiac output increase range = 4-fold to 7-fold Increase in coronary blood flow = 3-fold to 4-fold Decrease in coronary capillary flow phase = During left ventricle contraction Resting coronary blood flow rate = 70 ml/min/100 g</p> Signup and view all the answers

    Match the coronary arteries with the areas they supply:

    <p>Left coronary artery = Posterior part of the left ventricle (80-90%) Right coronary artery = Anterior part of the left ventricle</p> Signup and view all the answers

    Match the type of blood flow regulation with its description:

    <p>Regulation of coronary blood flow = Proportional to cardiac oxygen needs Decrease in left ventricular coronary blood flow = Occurs during systole Oxygen removal in coronary blood = About 70% during circulation through the heart Subendocardial arterial plexus = Supplies the deepest layer of the heart muscle</p> Signup and view all the answers

    Match the source of muscle nutrition with the level of significance:

    <p>Nutrient capillaries from blood = Significant source for heart muscle Blood inside cardiac chambers = Minuscule source of muscle nutrition Coronary arteries = Main source of blood supply to heart muscles Inner endocardial surface = Only a slight level of nutritional support</p> Signup and view all the answers

    Match the coronary blood flow changes with the phases of the heart cycle:

    <p>Systole = Coronary blood flow decreases Diastole = Coronary blood flow increases Endocardial surface nutrition = Insufficient during systole Epicardial arteries = Supply blood during diastole</p> Signup and view all the answers

    Match the statement about coronary blood flow with the correct fact:

    <p>Oxygen demand = Major factor in local coronary blood flow regulation Nutritional blood supply to the heart = Necessary due to limited direct nutrition Capillary blood flow during exercise = Increases to meet added oxygen demands Coronary blood flow during heavy exercise = Significantly regulated by muscle activity</p> Signup and view all the answers

    Study Notes

    Blood Flow Regulation in Skeletal Muscle at Rest and During Exercise

    • Strenuous exercise causes a large increase in blood flow to skeletal muscles, surpassing the normal circulatory system's capacity
    • Sympathetic vasoconstrictor nerve fibers secrete norepinephrine, which can decrease blood flow through resting muscles
    • This vasoconstriction helps to prevent decreases in arterial pressure during shock or stress
    • Skeletal muscles have sympathetic vasodilator nerves in some animals, but their role in blood flow regulation is unclear
    • During exercise, the body shifts blood from inactive areas to active muscles
    • This “lending” of blood supply to the muscles allows for increased muscle activity and performance
    • The coronary and cerebral systems are spared from this vasoconstriction due to minimal innervation
    • This allows for continued oxygen and nutrient delivery to the brain and heart during physical exertion
    • Sympathetic stimulation contracts veins and other capacitative vessels, leading to a greater increase in mean systemic filling pressure
    • Tensing of abdominal and other skeletal muscles during exercise further increases mean systemic filling pressure
    • The combination of increased mean systemic filling pressure and decreased resistance to venous return elevates the venous return curve
    • This shift in the venous return curve significantly contributes to the increase in cardiac output during exercise

    Control of Skeletal Muscle Blood Flow

    • Decreased oxygen in muscle tissue greatly enhances muscle blood flow
    • The body actively distributes blood towards active muscle groups while reducing flow to inactive regions
    • This redistribution is crucial for optimal oxygen and nutrient delivery to the highly active muscles
    • The coronary and cerebral systems are spared from vasoconstriction, allowing for continued oxygen and nutrient delivery to the brain and heart

    Coronary Circulation and Ischemic Heart Disease

    • Coronary arteries deliver blood to the heart muscle, providing the oxygen and nutrients essential for cardiac function
    • The epicardial coronary arteries carry blood to the myocardium, the heart muscle
    • The left coronary artery supplies blood to the anterior and left lateral portions of the left ventricle, while the right coronary artery supplies most of the right ventricle
    • Coronary blood flow is regulated in proportion to the oxygen needs of the cardiac muscle
    • Cardiac muscle compression during systole causes phasic changes in coronary blood flow
    • During ventricular contraction, coronary blood flow decreases briefly, but increases sharply during diastole when the heart relaxes
    • Angina pectoris, also known as chest pain, is typically caused by narrowing or blockage of the coronary arteries, leading to reduced oxygen supply to the heart muscle
    • The pain of angina is often described as hot, pressing, and constricting
    • Vasodilator drugs like nitroglycerin or nitrates can provide immediate relief from anginal pain
    • Drugs that block sympathetic beta-adrenergic receptors, known as beta-blockers, can prevent sympathetic enhancement and decrease heart rate and metabolism
    • This reduces the heart's oxygen demand, lowering the chances of anginal pain
    • Percutaneous coronary intervention (PCI), also known as angioplasty, involves inserting a balloon catheter into a blocked coronary artery to widen the vessel
    • A stent, a small tube, is often placed after angioplasty to maintain the vessel’s openness
    • Despite the success of PCI, restenosis, the narrowing or blockage of the coronary artery, can occur in a significant portion of patients
    • Restenosis is usually caused by the formation of scar tissue within the stent
    • Coronary artery bypass graft (CABG) is a surgical intervention that uses a vein or artery from another part of the body to bypass the blocked coronary artery
    • CABG helps restore blood flow to the heart muscle and is often performed for multiple blocked arteries or complex blockages

    Heart Function After Recovery From Myocardial Infarction

    • Myocardial infarction, also known as a heart attack, occurs when the blood supply to the heart muscle is abruptly cut off, leading to damage or death of heart muscle
    • Although some hearts recover fully from a myocardial infarction, others experience permanent pumping capability reduction
    • This reduction can impact the heart's ability to pump blood effectively, potentially leading to complications

    Exercise and Blood Flow

    • During muscle contraction, blood flow in the calf muscle is reduced significantly compared to rest.
    • This is due to compression of blood vessels by the contracting muscle.
    • A key factor in vasodilation during exercise is adenosine, but it cannot sustain vasodilation for long periods.
    • Other vasodilators are essential for maintaining increased blood flow during prolonged exercise.
    • These include potassium ions, adenosine triphosphate (ATP), lactic acid, and carbon dioxide.

    Sympathetic Activation

    • Sympathetic nervous system activation during exercise causes increased heart rate and pumping strength, as well as constriction of arterioles in most of the body.
    • However, blood vessels in the active muscles remain dilated due to local vasodilator effects.
    • This redistribution of blood flow is critical for supplying the muscles with the oxygen and nutrients they need during exercise.

    Coronary Blood Flow

    • Blood flow in the coronary arteries is influenced by the mechanical compression of the heart muscle during contraction.
    • Subendocardial arteries face greater compression during systole, leading to possible blood flow reduction there.
    • The subendocardial plexus, a network of arteries, compensates for this compression.

    Subendocardial Infarction

    • Subendocardial muscle is vulnerable to infarction due to its higher oxygen demand and reduced blood flow during systole.
    • Infarction in this area can spread outward towards the epicardium.

    Causes of Death After Acute Coronary Occlusion

    • Decreased cardiac output is a major cause of death due to the weakened pumping ability of the heart.
    • Systolic stretch, where nonfunctional muscle bulges outward, further reduces pumping efficiency.
    • Cardiac shock occurs when the heart cannot deliver adequate blood flow to the body.
    • Damming of blood in the venous system, particularly in the lungs, can lead to pulmonary edema and death.
    • Ventricular fibrillation, a chaotic rhythm of the heart's lower chambers, is another common cause of death.

    Muscle Blood Flow During Exercise

    • During rhythmic muscle contractions, blood flow in the calf is much lower during contractions than between contractions.
    • The primary cause of reduced blood flow during contraction is compression of blood vessels by the contracting muscles.
    • During prolonged muscle contractions, blood flow is sustained due to the release of vasodilator substances, including adenosine, potassium ions, ATP, lactic acid, and carbon dioxide.

    Sympathetic Activation and Its Effects

    • Sympathetic activation during exercise increases heart rate and contractility.
    • Sympathetic stimulation also constricts peripheral blood vessels, redirecting blood flow to active muscles.

    Cardiac Muscle Metabolism

    • Cardiac muscle relies heavily on oxidative phosphorylation for energy.
    • Cardiac muscle has a high mitochondrial density to support this energy demand.
    • While adenosine is a known vasodilator, it cannot sustain vasodilation in skeletal muscle for extended periods, suggesting other mechanisms are at play during prolonged exercise.

    Coronary Blood Flow

    • Coronary blood flow is influenced during both systole and diastole.
    • The left ventricular muscle relies on the coronary sinus for venous return.
    • The right ventricular muscle uses smaller anterior cardiac veins that flow directly into the right atrium.

    Ischemic Heart Disease

    • Ischemic heart disease is a leading cause of death in Western countries.
    • It stems from insufficient coronary blood flow, often due to atherosclerosis.
    • Atherosclerosis can lead to sudden death or gradual heart failure.

    Atherosclerosis

    • Atherosclerosis involves plaque buildup in arteries, narrowing the lumen and reducing blood flow.
    • Thrombosis, a blood clot formation, can further occlude coronary arteries, causing a heart attack.
    • Collateral circulation, the development of alternate blood vessels, can offer some protection against ischemic damage.

    Myocardial Infarction

    • A myocardial infarction occurs when an artery is blocked, causing tissue death in the heart muscle.
    • The severity of damage depends on the extent of occlusion and collateral circulation.
    • Fibrillation, irregular heart rhythm, can occur during the first 10 minutes or after an hour post-infarction.

    Factors Leading to Fibrillation

    • Potassium depletion from the ischemic heart muscle can increase the likelihood of fibrillation.
    • Injury currents, caused by ischemia, can also lead to fibrillation.
    • Fibrillation can result in the stretching of the thin dead muscle wall, possibly even leading to heart rupture.

    Coronary Circulation

    • Coronary artery disease is responsible for one-third of deaths in industrialized countries
    • Most older adults have some impairment of coronary artery circulation
    • Understanding coronary circulation is an important topic in medicine
    • Coronary blood flow averages 5% of cardiac output
    • 70 ml/min/100 g of heart weight is the normal coronary blood flow in resting people
    • Coronary blood flow during strenuous exercise can increase 3 to 4 times
    • Coronary blood flow is a major factor in local coronary blood flow regulation
    • 70% of the oxygen in coronary blood is removed as it flows through the heart muscle
    • Sympathetic nervous system stimulation increases heart rate and contractility, and increases metabolic needs
    • Vagal stimulation has a slightly depressive effect on heart contractility and slows the heart
    • Lactic accumulation in the cardiac tissue could be linked to cardiac pain
    • More than 95% of the metabolic energy from food is used to form ATP in mitochondria
    • The effects of sympathetic and vagal stimulation are mostly opposite
    • Sympathetic stimulation increases heart rate and contractility, and increases metabolic needs
    • Vagal stimulation has a slightly depressive effect on heart contractility and slows the heart
    • Lactic acid accumulation in the cardiac tissue could be linked to cardiac pain
    • ATP is the main source of energy for heart muscle contraction and other cell functions

    Coronary Blood Supply

    • Coronary arteries are located on the heart surface
    • The left coronary artery supplies the anterior and left lateral portions of the left ventricle
    • The right coronary artery supplies most of the right ventricle and the posterior part of the left ventricle
    • Inner one-tenth millimeter of the endocardial surface receives nutrition directly from the blood in the heart chambers
    • Cardiac muscle compression during systole and diastole causes changes in coronary blood flow

    Coronary Artery Disease

    • When the area of ischemia is small, little or no death of muscle cells may occur, but part of the muscle often becomes temporarily nonfunctional
    • When the area is large, some of the muscle fibers in the center die within 1 to 3 hours if there is total cessation of coronary blood supply
    • After an acute infarct, there is little danger of rupture of the ischemic portion of the heart during the first day
    • Rupture is more likely a few days later, as the dead muscle fibers begin to degenerate and the area of dead fibers enlarges
    • Anginal pain can be relieved in most patients after coronary bypass surgery
    • Bypass surgery can provide normal life expectancy if the heart is not severely damaged
    • Coronary angioplasty uses a balloon-tipped catheter to stretch diseased arteries

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    Description

    Explore how blood flow to skeletal muscles changes at rest and during exercise. This quiz covers mechanisms like sympathetic vasoconstriction and the body's ability to redirect blood supply to active muscles while sparing critical systems like the coronary and cerebral regions.

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