Exercise and Coronary Blood Flow
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Questions and Answers

What is the primary controller of coronary blood flow?

Local metabolism

What is the function of the left coronary artery?

Supplying blood to the walls of LA, LV, and most of the interventricular septum including AV bundle

What is the function of the right coronary artery?

Supplying blood to the walls of RA, RV, SA and AV node, and posterior part of interventricular septum (proximal portion of AV bundle of His)

What is the main consequence of anaerobic glycolysis in the myocardium?

<p>Increased production of lactic acid</p> Signup and view all the answers

What stimulates the release of vasodilators in response to the need of cardiac musculature for oxygen?

<p>Anaerobic glycolysis</p> Signup and view all the answers

What is the role of sympathetic stimulation in arterioles during exercise?

<p>Sympathetic stimulation causes arterioles to close mechanically during systole and increases oxygen and metabolic demand during exercise.</p> Signup and view all the answers

How does sympathetic stimulation affect the work output of the heart during strenuous exercise?

<p>Sympathetic stimulation increases the work output of the heart by 6-9 times during strenuous exercise.</p> Signup and view all the answers

What percentage of coronary blood flow does the heart use during strenuous exercise?

<p>The heart uses 70-80% of coronary blood flow during strenuous exercise.</p> Signup and view all the answers

How does sympathetic stimulation affect the demand for oxygen at rest?

<p>Sympathetic stimulation increases the demand for oxygen at rest, which must be met by increased blood flow.</p> Signup and view all the answers

What is the role of sympathetic stimulation in skeletal muscle arteries?

<p>Sympathetic stimulation causes vasoconstriction of skeletal muscle arterioles via noradrenaline acting on α1 receptors, but adrenaline acting on β2 receptors causes vasodilation.</p> Signup and view all the answers

What determines the coronary dominance in the majority of people?

<p>The artery that gives off the posterior interventricular/posterior descending artery</p> Signup and view all the answers

What are the components of the cardiac conduction system?

<p>Sinu-atrial node (SA node), Atrioventricular node (AV node), Atrioventricular bundle (bundle of His), Left bundle branch, Right bundle branch, Purkinje fibers</p> Signup and view all the answers

What is the function of the coronary sinus?

<p>To drain 60% of the venous blood of the heart into the right atrium</p> Signup and view all the answers

What are the components of the cardiac conduction system?

<p>SA node, AV node, Bundle of His, Bundle branches, Purkinje fibers</p> Signup and view all the answers

What is the role of the sympathetic nervous system in the heart?

<p>Increase heart rate, increase force of contraction, dilate coronary arteries</p> Signup and view all the answers

What is the role of the parasympathetic nervous system in the heart?

<p>Decrease heart rate, constrict coronary arteries</p> Signup and view all the answers

What are the sources of figures and images mentioned in the text?

<p>DAFFNER, DRAKE, GILROY, KELLEY, MOORE, NETTER, SOBOTTA, ONI</p> Signup and view all the answers

What are the learning outcomes of the lecture on coronary circulation and the conduction system?

<ol> <li>Describe the origin, course and distribution of the coronary arteries. 2. Explain the importance of the anastomoses between the coronary arteries. 3. Describe the venous drainage of the heart. 4. Describe the anatomical position of the conducting system of the heart and how it controls heart rate. 5. List the arteries that supply the conduction system of the heart. 6. Describe the autonomic innervation of the heart. 7. Discuss the effects of ischaemia of the myocardium and how it may affect the conducting system. 8. Explain where pain originating from the heart is referred to and why. 9. Identify major branches of coronary arteries on angiograms.</li> </ol> Signup and view all the answers

How is the heart innervated and controlled?

<p>The heart is innervated by the autonomic nervous system. The sympathetic and parasympathetic divisions of the autonomic nervous system control the heart rate and rhythm.</p> Signup and view all the answers

Why can't the heart use the oxygenated blood in its chambers?

<p>The oxygenated blood in the chambers of the heart is meant to be delivered to the rest of the body's tissues. The heart itself requires a separate blood supply through the coronary arteries to meet its own oxygen demands.</p> Signup and view all the answers

What is the long-term regulation of blood volume and pressure controlled by?

<p>The renal-body fluid feedback system and the level of salt and water intake.</p> Signup and view all the answers

How are changes in blood volume and blood osmotic pressure sensed and altered?

<p>Changes in blood volume and blood osmotic pressure are sensed and altered by the release of antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system.</p> Signup and view all the answers

What triggers the release of ADH?

<p>ADH is released in response to increased osmotic pressure and hypovolemia (10% loss or greater).</p> Signup and view all the answers

How does hypotension affect ADH release?

<p>Hypotension leads to decreased arterial baroreceptor firing, increased sympathetic activity, and increased ADH release.</p> Signup and view all the answers

What is the role of angiotensin II in the regulation of blood volume and pressure?

<p>Angiotensin II stimulates the release of ADH and plays a role in vasoconstriction and sodium reabsorption to increase blood volume and pressure.</p> Signup and view all the answers

What is the role of ADH (arginine vasopressin) in increasing blood volume and reducing urine production?

<p>ADH increases water permeability in renal collecting ducts, leading to increased reabsorption of water and decreased urine production.</p> Signup and view all the answers

How does the release of ADH change in severe hypovolemic shock?

<p>ADH release is high in severe hypovolemic shock, leading to vasoconstriction and increased total peripheral resistance.</p> Signup and view all the answers

What is the function of the renin-angiotensin-aldosterone system (RAAS) in regulating blood volume?

<p>RAAS helps regulate blood volume by increasing sodium and water reabsorption in the kidneys, as well as vasoconstriction.</p> Signup and view all the answers

What is the role of atrial-natriuretic hormone (ANH) in counteracting the effects of the RAAS system?

<p>ANH is released in response to stretch of the atria and helps oppose the effects of the RAAS system, potentially counteracting volume overload.</p> Signup and view all the answers

What are the classifications of shock based on the percentage of blood loss?

<p>Class 1: 10-15% blood loss; Class 2: 15-30% blood loss; Class 3: 30-40% blood loss; Class 4: &gt;40% blood loss.</p> Signup and view all the answers

What is the primary purpose of the baroreceptor reflex control?

<p>The primary purpose of the baroreceptor reflex control is to reduce the minute-to-minute variations or arterial pulse.</p> Signup and view all the answers

What are the target effectors in the reflex control of blood pressure?

<p>The target effectors in the reflex control of blood pressure are the heart and blood vessels.</p> Signup and view all the answers

What is the role of the sympathetic nervous system in blood vessels?

<p>The sympathetic nervous system exerts a continuous low-level tone, known as sympathetic vasoconstrictor tone, which affects total peripheral resistance and keeps the blood vessels partially constricted.</p> Signup and view all the answers

What is the role of the parasympathetic nervous system in the heart?

<p>The parasympathetic nervous system controls heart rate by reducing its activity.</p> Signup and view all the answers

How is integration of baroreceptor and cardiopulmonary baroreceptor signals controlled?

<p>The integration of baroreceptor and cardiopulmonary baroreceptor signals is controlled by the medullary cardiovascular control (MCVC) center, also known as the &quot;vasomotor&quot; center.</p> Signup and view all the answers

What are the fundamental components of a reflex control system?

<ol> <li>Internal variable to be maintained</li> <li>Receptors sensitive to change in the variable</li> <li>Afferent pathways from the receptors</li> <li>An integrating center for the afferent inputs</li> <li>Efferent pathways from the integrating center</li> <li>Target effectors that alter their activities</li> </ol> Signup and view all the answers

Where are the main baroreceptor locations?

<p>Walls of aorta and Carotid artery</p> Signup and view all the answers

What is the function of baroreceptors?

<p>Baroreceptors are stretch receptors that sense changes in blood pressure. Their firing rate increases when blood pressure increases and decreases when blood pressure decreases.</p> Signup and view all the answers

What are the roles of the nervous control of arterial pressure?

<p>The nervous control of arterial pressure allows for rapid changes in arterial pressure. It can increase arterial pressure to 2x normal within 5-10 seconds and decrease arterial pressure to 50% normal within 10-40 seconds.</p> Signup and view all the answers

What is the purpose of controlling blood pressure?

<p>The purpose of controlling blood pressure is to maintain tissue perfusion throughout the body and to keep a relatively constant arterial blood pressure. Blood pressure that is too low can result in inadequate blood flow to organs, while blood pressure that is too high can cause damage to vessels and organs.</p> Signup and view all the answers

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