Cardiac Physiology Quiz
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Questions and Answers

Which of the following factors would increase preload?

  • Arterial dilation
  • Venous constriction (correct)
  • Arterial constriction
  • Venous dilation

Which of the following accurately describes the relationship between blood vessel radius and resistance according to Poiseuille's Equation?

  • Resistance is inversely proportional to the radius squared.
  • Resistance is inversely proportional to the radius to the 4th power. (correct)
  • Resistance is directly proportional to the radius to the 4th power.
  • Resistance is directly proportional to the radius.

Which of the following conditions would decrease afterload?

  • Venous dilation
  • Arterial constriction
  • Arterial dilation (correct)
  • Venous constriction

A patient with a condition requiring a permanent pacemaker is likely experiencing:

<p>Impaired electrical conduction in the heart (A)</p> Signup and view all the answers

Which of the following arteries exhibit the Windkessel Effect?

<p>Aorta (B)</p> Signup and view all the answers

If blood vessel B has a radius twice that of blood vessel A, and both vessels have the same length, what is the ratio of blood flow in vessel B to vessel A?

<p>1:16 (A)</p> Signup and view all the answers

Which of the following is a characteristic of the aorta?

<p>Highest blood flow velocity (D)</p> Signup and view all the answers

Which of the following is NOT a direct consequence of coarctation of the aorta?

<p>Decreased afterload (D)</p> Signup and view all the answers

What is the ECG pattern suggestive of atrial fibrillation?

<p>Absent P waves (A)</p> Signup and view all the answers

Which of the following is a key characteristic of the Bezold-Jarisch reflex?

<p>It is a bradycardia-inducing reflex. (C)</p> Signup and view all the answers

What is the ECG pattern associated with hyperkalemia?

<p>Peaked T waves (D)</p> Signup and view all the answers

Which condition is characterized by an increase in jugular venous pressure during inspiration?

<p>Constrictive pericarditis (A)</p> Signup and view all the answers

Which of the following is a characteristic pattern seen in the ECG of a patient with Wolf-Parkinson-White Syndrome?

<p>Delta waves (B)</p> Signup and view all the answers

Which of the following statements about the Frank-Starling law is TRUE?

<p>It explains the relationship between preload and stroke volume. (D)</p> Signup and view all the answers

Which of the following is a common cause of First Degree Heart Block?

<p>Rheumatic fever (A)</p> Signup and view all the answers

What is the most dangerous type of second-degree heart block?

<p>Mobitz Type 2 (D)</p> Signup and view all the answers

What is the ECG pattern typically seen in patients with stable Ventricular Tachycardia?

<p>A characteristic pattern distinct from other arrhythmias (A)</p> Signup and view all the answers

Which of the following is TRUE regarding Torsades de Pointes?

<p>It is associated with QT prolongation. (C)</p> Signup and view all the answers

Which drug class is known to cause Torsades de Pointes by blocking potassium channels?

<p>Class III antiarrhythmic drugs (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic feature of cardiac tamponade?

<p>Presence of a delta wave (A)</p> Signup and view all the answers

Which of the following conditions is most likely to be associated with Osborn waves (J waves) on an ECG?

<p>Severe hypothyroidism (D)</p> Signup and view all the answers

What is the mechanism by which dopamine helps treat oliguria?

<p>It causes vasodilation in the renal blood vessels to maintain GFR. (B)</p> Signup and view all the answers

Which of the following is TRUE regarding the Bainbridge reflex?

<p>It is activated by an increase in venous return. (B)</p> Signup and view all the answers

Which area of the chest is best for auscultation of the aortic valve?

<p>Right side of the sternum, 2nd intercostal space (A)</p> Signup and view all the answers

What is the resting membrane potential of cardiac myocytes?

<p>-90 mV (D)</p> Signup and view all the answers

During which phase of the action potential does potassium efflux begin?

<p>Early Repolarization (Phase 1) (B)</p> Signup and view all the answers

What causes the first heart sound (S1)?

<p>Closure of mitral and tricuspid valves (A)</p> Signup and view all the answers

Which heart sound is typically not heard in normal adults?

<p>S3 (C)</p> Signup and view all the answers

What type of murmur is associated with mitral regurgitation?

<p>Pan Systolic (Holosystolic) Murmur (B)</p> Signup and view all the answers

Which heart sound occurs during atrial contraction?

<p>S4 (D)</p> Signup and view all the answers

What phase of the cardiac action potential is characterized by balanced calcium influx and potassium efflux?

<p>Plateau Phase (Phase 2) (C)</p> Signup and view all the answers

Which of the following is a characteristic of Crescendo-Decrescendo murmurs?

<p>Intensity increases then decreases (D)</p> Signup and view all the answers

Which of the following conditions is characterized by a diastolic rumble with an opening snap?

<p>Mitral Stenosis (B)</p> Signup and view all the answers

What is the primary wave associated with atrial contraction in Jugular Venous Pressure (JVP) measurements?

<p>A wave (D)</p> Signup and view all the answers

Which phase of the cardiac cycle begins with mitral valve closure and is characterized by pressure rising without a change in volume?

<p>Isovolumetric Contraction (C)</p> Signup and view all the answers

Which abnormal JVP pattern is characterized by prominent X descent and is commonly seen in cardiac tamponade?

<p>Prominent X descent (A)</p> Signup and view all the answers

Which of the following is NOT typically associated with aortic regurgitation?

<p>Atrial fibrillation (A)</p> Signup and view all the answers

Marfan Syndrome is associated with which of the following cardiac complications?

<p>Aortic dissection (D)</p> Signup and view all the answers

The dichroic notch occurs during which phase of the cardiac cycle?

<p>Rapid Ejection Phase (A)</p> Signup and view all the answers

Which reflex is known to increase heart rate in response to increased venous return?

<p>Bainbridge Reflex (D)</p> Signup and view all the answers

Mitral regurgitation is best characterized by which change in the left ventricular pressure volume loop?

<p>Short and extending to both sides (B)</p> Signup and view all the answers

What does the baroreceptor reflex primarily respond to?

<p>Increased blood pressure (D)</p> Signup and view all the answers

Which abnormal JVP pattern is associated with atrioventricular dissociation?

<p>Canon A waves (B)</p> Signup and view all the answers

Which of the following is a characteristic finding of mitral stenosis?

<p>Diastolic rumble with opening snap (D)</p> Signup and view all the answers

What is likely to occur during the isovolumetric relaxation phase of the cardiac cycle?

<p>Aortic valve closure (B)</p> Signup and view all the answers

Which condition may present with large A waves in JVP measurements?

<p>Tricuspid Stenosis (A)</p> Signup and view all the answers

Flashcards

What is preload?

The end-diastolic volume of the heart, representing the amount of blood in the heart before contraction. It's directly affected by venous return.

What is afterload?

The pressure the left ventricle needs to overcome to push blood into the aorta. It's influenced by the resistance of blood vessels.

Describe coarctation of the aorta

A condition where the aorta is narrowed, leading to increased pressure before the narrowing and decreased pressure after it.

What is Poiseuille's Law?

A principle explaining how blood flow changes with vessel size. Flow is directly proportional to the radius to the 4th power.

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Explain the Windkessel effect

The recoil of major arteries after being stretched by blood flow. It helps maintain continuous blood flow when the heart is not pumping.

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Why does the aorta have the highest blood pressure?

The aorta has the highest blood pressure because it receives blood directly from the heart during contraction.

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How do venous dilation and constriction affect preload?

Venous dilation decreases preload as blood pools in the periphery, while venous constriction increases preload by pushing more blood towards the heart.

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How do arterial dilation and constriction affect afterload?

Arterial dilation decreases afterload as it reduces resistance, making it easier for the heart to pump blood. Arterial constriction increases afterload due to higher resistance.

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Cardiac Myocyte Resting Membrane Potential

The resting membrane potential of a cardiac myocyte is -90 mV, equal to the potassium equilibrium potential. This is different from a neuron's -70 mV resting potential, which is equal to the chloride equilibrium potential.

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Depolarization (Phase 0)

The initial phase of an action potential where sodium influx causes rapid depolarization of the cell membrane.

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Early Repolarization (Phase 1)

The short period following depolarization where potassium efflux begins, leading to a slight decrease in membrane potential.

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Plateau Phase (Phase 2)

A sustained period of relatively stable membrane potential where calcium influx and potassium efflux are balanced.

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Repolarization (Phase 3)

The final phase of an action potential where potassium efflux predominates, leading to a rapid decrease in membrane potential.

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Essential Calcium

Calcium entering the cell during the plateau phase triggers the release of calcium from the sarcoplasmic reticulum (SR) via ryanodine receptors (RYR). This process leads to muscle contraction.

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First Heart Sound (S1)

The first heart sound, heard during isovolumetric contraction, is caused by the closure of the mitral and tricuspid valves. This prevents blood backflow into the atria.

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Second Heart Sound (S2)

The second heart sound, heard during the beginning of isovolumetric relaxation (protodiastole), is caused by the closure of the aortic and pulmonic valves. This prevents blood backflow from the aorta and pulmonary trunk.

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Valsalva Maneuver

A maneuver that increases intrathoracic pressure, compressing the aorta and activating aortic baroreceptors, leading to a decreased heart rate.

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Baroreceptor Reflex

A reflex that regulates blood pressure by sensing pressure changes in the aorta and carotid arteries.

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Carotid Sinus Reflex

A reflex that is triggered by increased pressure in the carotid sinus, leading to a decrease in heart rate.

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Frank-Starling Law

The Frank-Starling law states that the more blood volume in the ventricle (preload), the higher the stroke volume will be.

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EDV and SV Relationship

The end-diastolic volume (EDV) is directly proportional to the stroke volume (SV).

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Sawtooth Waves on ECG

Sawtooth waves on an ECG are seen with atrial flutter.

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Absent P Waves on ECG

Atrial fibrillation is characterized by absent P waves on an ECG.

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Dopamine

A positive inotropic drug that increases myocardial contractility and is used in patients with shock and oliguria.

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Bezold-Jarisch Reflex

A reflex that causes bradycardia, often associated with hypotension and pain.

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Bainbridge Reflex

A positive feedback loop that increases heart rate in response to increased venous return.

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Irregularly Irregular Rhythm

The ECG pattern seen with atrial fibrillation.

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PSVT ECG Pattern

The ECG pattern seen with paroxysmal supraventricular tachycardia (PSVT).

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Ventricular Tachycardia ECG Pattern

The ECG pattern seen with stable ventricular tachycardia.

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Torsades de Pointes

The ECG pattern characterized by a twisting, irregular QRS complex.

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Delta Waves

A characteristic upswinging wave seen on the ECG with Wolf-Parkinson-White Syndrome.

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What is Marfan Syndrome?

A connective tissue disorder affecting the fibrillin 1 gene, leading to potential complications like aortic dissection.

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What is Mitral Valve Prolapse?

A condition characterized by a midsystolic click, often an isolated finding but potentially associated with Marfan Syndrome.

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What is Mitral Stenosis?

A heart condition characterized by a diastolic rumble with an opening snap, often associated with rheumatic heart disease. It can begin as mitral regurgitation and progress to stenosis.

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What is Aortic Regurgitation?

A condition associated with a blowing diastolic murmur, bounding pulse, head bobbing, and widened pulse pressure.

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What is the Isovolumetric Contraction phase in the left ventricular pressure-volume loop?

The first phase of the cardiac cycle where the left ventricle contracts, but the aortic valve is closed due to pressure, causing pressure to rise from 5 to 80 mm Hg while volume remains constant. This is when the mitral valve closes.

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What is the Rapid Ejection Phase in the left ventricular pressure-volume loop?

The phase where the aortic valve opens and blood is quickly ejected from the left ventricle, further increasing pressure to 120 mm Hg.

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What is the Slow Ejection Phase in the left ventricular pressure-volume loop?

As the ventricle continues contracting, the pressure decreases, leading to slower ejection of blood. Pressure declines to around 80 mm Hg.

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What is the Isovolumetric Relaxation Phase in the left ventricular pressure-volume loop?

The aortic valve closes as pressure in the left ventricle falls below aortic pressure. The ventricle begins to relax. Pressure drops quickly with no change in volume. This is when the mitral valve opens.

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What is the Ventricular Filling Phase in the left ventricular pressure-volume loop?

As the ventricle relaxes, the mitral valve opens, allowing blood to flow from the left atrium into the left ventricle, decreasing pressure.

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What is Jugular Venous Pressure (JVP)?

A measurement of the pressure in the right atrium, observed in the internal jugular vein.

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What is the A wave in JVP?

This positive wave in JVP is due to atrial contraction, causing a pressure increase.

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What is the X descent in JVP?

This negative wave in JVP is due to atrial relaxation, leading to a decrease in pressure as blood moves from the jugular vein to the right atrium.

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What is the C wave in JVP?

This positive wave in JVP is caused by bulging of the tricuspid valve into the atrium during isovolumetric contraction of the right ventricle, increasing pressure in the right atrium.

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What is the V wave in JVP?

This positive wave in JVP is due to the filling of the atrium, increasing the pressure in the right atrium.

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What is the Y descent in JVP?

This negative wave in JVP is due to atrial emptying when the tricuspid valve opens, allowing blood to flow into the right ventricle, resulting in reduced pressure.

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What is the Dichroic Notch?

A notch formed during the rapid ejection phase of the cardiac cycle, due to the closure of the aortic valve.

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Study Notes

Cardiac Physiology

  • Cardiac myocyte resting membrane potential = -90 mV, equal to potassium equilibrium potential.
  • Neuron resting membrane potential = -70 mV, equal to chloride equilibrium potential.
  • Action Potential Phases:
    • Depolarization (Phase 0): Sodium influx.
    • Early Repolarization (Phase 1): Potassium efflux begins.
    • Plateau Phase (Phase 2): Calcium influx and potassium efflux are balanced.
    • Repolarization (Phase 3): Potassium efflux predominates.
  • Essential Calcium:
    • Calcium entering during the plateau phase is "essential calcium."
    • Triggers calcium release from the sarcoplasmic reticulum (SR) via ryanodine receptors (RYR).
    • Leads to muscle contraction.

Heart Sounds

  • First Heart Sound (S1):
    • Occurs during isovolumetric contraction.
    • Caused by closure of mitral and tricuspid valves, preventing backflow.
  • Second Heart Sound (S2):
    • Occurs during protodiastole or isovolumetric relaxation.
    • Caused by closure of aortic and pulmonic valves.
  • Third Heart Sound (S3):
    • Heard during rapid ventricular filling.
    • Typically not heard in normal adults.
    • Can be physiological in children and pregnant individuals.
    • May be associated with hyperdynamic states.
  • Fourth Heart Sound (S4):
    • Heard during atrial contraction.
    • A low-pitched sound.
    • Occurs as ventricles fill with ~30% of blood volume.
  • Low-Pitched Heart Sounds:
    • S3, S4, and Tumor Plop are low-pitched heart sounds.
  • Tumor Plop Sound:
    • Associated with atrial myxoma (a tumor in the left atrium).
    • Created by the tumor hitting the mitral valve wall during contractions.

Murmurs

  • Pan Systolic (Holosystolic) Murmurs:
    • Occur throughout systole.
    • Associated with mitral regurgitation, tricuspid regurgitation, and ventricular septal defect (VSD).
  • Cresendo-Decresendo Murmurs:
    • Intensity increases then decreases during systole.
    • Also called diamond-shaped murmurs.
    • Associated with pulmonic stenosis, subaortic stenosis, and hypertrophic obstructive cardiomyopathy (HOCM).
  • Continuous Murmurs:
    • Heard during systole and diastole.
    • Associated with patent ductus arteriosus (PDA), continuous blood shunting from aorta to pulmonary trunk.

Other Important Concepts

  • Mitral Valve Prolapse:
    • Associated with midsystolic clicks.
    • Can be an isolated finding or associated with Marfan syndrome.
  • Marfan Syndrome:
    • Connective tissue disorder affecting the fibrillin-1 gene.
    • Can lead to aortic dissection, a serious medical emergency.
  • Mitral Stenosis:
    • Characterized by diastolic rumble and opening snap.
    • Often associated with rheumatic heart disease.
    • Initially presents as mitral regurgitation, progressing to stenosis in chronic cases.
  • Aortic Regurgitation:
    • Associated with blowing diastolic murmur, bounding pulse, head bobbing, and widened pulse pressure.

Left Ventricular Pressure-Volume Loop

  • Shows pressure and volume changes during a cardiac cycle.
  • End Systolic Volume (ESV): ~50 mL.
  • End Diastolic Volume (EDV): ~120 mL.
  • Isovolumetric Contraction: Mitral valve closes, pressure rises (5 mmHg to 80 mmHg) but volume remains constant.
  • Rapid Ejection Phase: Aortic valve opens, pressure rises further (to 120 mmHg), rapid blood ejection.
  • Slow Ejection Phase: Ventricular pressure decreases; slower ejection.
  • Isovolumetric Relaxation: Aortic valve closes when ventricular pressure falls below aortic pressure. Mitral valve opens. Pressure drops quickly, volume remains constant.
  • Ventricular Filling: Mitral valve open, blood flows from atrium to ventricle. Pressure drops, reflecting ventricular relaxation.
  • Changes in the loop:
    • Narrow and tall: Aortic stenosis.
    • Extending to the right side: Aortic regurgitation.
    • Short: Mitral stenosis.
    • Extending to both sides: Mitral regurgitation.

Jugular Venous Pressure (JVP)

  • Measures right atrial pressure, observed in the internal jugular vein.
  • A wave: Positive wave due to atrial contraction.
  • X descent: Negative wave due to atrial relaxation; blood moving to right atrium.
  • C wave: Positive wave from tricuspid valve bulging into atrium during right ventricular contraction.
  • V wave: Positive wave due to atrial filling.
  • Y descent: Negative wave from atrial emptying into the right ventricle.
  • Abnormal JVP: Refer to notes for various scenarios.

Other Relevant Cardiac Concepts (updated)

  • Dichroic Notch: Formed during rapid ejection phase due to aortic valve closure; prominent during slow ejection phase.

  • Cardiac Reflexes: All reflexes decrease heart rate except the Bainbridge reflex.

    • Cushing reflex: Increased intracranial pressure, bradycardia, Cushing ulcers.
    • Bainbridge reflex: Tachycardia induced by increased venous return, right atrial distention, or increased blood volume (e.g., normal saline).
    • Bezold-Jarisch reflex: Bradycardia, hypotension, and prolonged apnea triggered by chemicals like serotonin, capsaicin, veratridine.
    • Baroreceptor reflex: Negative feedback mechanism; triggered by increased blood pressure, leading to decreased heart rate and blood pressure. Activated by the aortic arch and carotid sinus. Mary's Law: Increased BP results in decreased heart rate. Manuevers and clamping above/below the carotid sinus activate baroreceptors.

  • Frank-Starling Law: Increased end-diastolic volume (preload) leads to increased stroke volume.

  • ECG Points:

    • Atrial Flutter: Sawtooth waves.
    • Atrial Fibrillation: Absent P waves.

  • Dopamine: Positive inotropic drug, increases myocardial contractility; used for shock and oliguria.

  • Important ECG Points (Auscultation Area): Refer to existing notes.

  • Additional Notes (updated):

    • ... (Refer back to existing notes for other key concepts)

...(Rest of the existing notes remain as is.)

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Description

Test your knowledge on cardiac physiology, focusing on key concepts such as resting membrane potential, action potentials, and heart sounds. This quiz covers the essential mechanisms involved in cardiac function and muscle contraction.

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