Cardiovascular physiology

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What is the main function of Purkinje fibers in the heart?

Control contraction of atria

Transmit electrical impulses from AV node to apex (correct)

Generate the lub-dub sound

Facilitate the closure of semilunar valves

Which phase in the cardiac contractile cells is characterized by a much larger release of Ca2+ known as Ca2+ sparks?

Repolarization phase

Plateau phase (correct)

Depolarization phase

Resting phase

What is the unique feature of the membrane potential in cardiac contractile cells during the plateau phase?

Drops to a negative level

Remains at resting membrane potential

Maintained close to the peak positive level (correct)

Fluctuates rapidly

Which component of an ECG represents the ventricular repolarization phase?

T wave Signup and view all the answers

What event in the heart causes the 'dub' sound in the cardiac cycle?

Closure of semilunar valves Signup and view all the answers

Which condition is characterized by disorganized and chaotic contraction of the ventricles?

Ventricular fibrillation Signup and view all the answers

What type of cells in the heart muscle are responsible for generating the pulse that causes contractions?

Autorhythmic cells Signup and view all the answers

Which type of nerve uses acetylcholine to bind to muscarinic receptors in the atria and slow the heart down?

Parasympathetic nerve Signup and view all the answers

What is the main ion movement responsible for giving rise to the pacemaker potential in autorhythmic cells?

Increased inward Na+ current Signup and view all the answers

What percentage of cardiac muscle cells do Contractile cells make up?

99% Signup and view all the answers

Which type of nerve uses noradrenaline and adrenaline to increase heart rate by binding to beta receptors of atria and ventricles?

Sympathetic nerve Signup and view all the answers

Where are most of the long-lasting Ca2+ channels located in contractile cells?

Transverse tubules Signup and view all the answers

What stimulates the opening of ryanodine receptor Ca2+ channels located on the sarcoplasmic reticulum?

Ca2+ influx from T tubules Signup and view all the answers

What distinguishes Autorhythmic cells from Contractile cells?

Autorhythmic cells don't contract Signup and view all the answers

Which of the following is not part of the normal electrical conduction pathway in the heart?

Internodal pathway Signup and view all the answers

What is the function of the AV node in the heart's electrical conduction system?

Delays the AP to allow atrial contraction to complete Signup and view all the answers

Which structure in the heart is known as the normal pacemaker?

SA node Signup and view all the answers

What is the primary role of Purkinje fibers in the heart?

Conduct electrical signals to the ventricles Signup and view all the answers

What is the role of autorhythmic cells in the heart?

Generating action potentials responsible for contraction Signup and view all the answers

Which ion movement is essential for the pacemaker potential in autorhythmic cells?

Increased inward Ca2+ current Signup and view all the answers

During which phase do contractile cells of the heart display pacemaker activity?

Resting phase Signup and view all the answers

What is the primary function of the autonomic nervous system in cardiac muscle excitation?

Controlling heart rate through neurotransmitter release Signup and view all the answers

Which type of nerve is responsible for slowing down the heart rate by binding to muscarinic receptors?

Vagus nerve Signup and view all the answers

During which phase in the cardiac contractile cells is the membrane potential maintained close to the peak positive level, leading to a much larger release of Ca2+ known as Ca2+ sparks?

Plateau phase Signup and view all the answers

Which specialized conducting fibers in the heart are larger than cardiomyocytes, have fewer myofibrils, and a large number of mitochondria, allowing for synchronized contractions of the ventricles?

Purkinje fibers Signup and view all the answers

Which electrical structure in the heart transmits electrical impulses from the AV node to the apex of the heart?

Purkinje fibers Signup and view all the answers

In cardiac excitation-contraction coupling, which ion's release from the sarcoplasmic reticulum induces muscle contraction in cardiac cells?

Calcium (Ca2+) Signup and view all the answers

Which phase in cardiac contractile cells is characterized by the maintenance of a membrane potential close to peak positivity due to a higher release of Ca2+ and is unique to these cells?

Plateau phase Signup and view all the answers

What is the primary function of the AV node in the heart's electrical conduction system?

Synchronization of atrial and ventricular contractions Signup and view all the answers

During which phase of the cardiac cycle does Ca2+ enter the cytosol from the T tubules stimulating the opening of Ca2+ channels on the sarcoplasmic reticulum?

Plateau phase Signup and view all the answers

Which component of the heart's electrical conduction system serves as the normal pacemaker and is responsible for generating the heart's electrical impulses?

SA node Signup and view all the answers

What is the purpose of the delay that occurs at the AV node in the heart's electrical conduction system?

To ensure complete atrial contraction before ventricular excitation begins Signup and view all the answers

Which part of the heart's electrical conduction system extends from the SA node to the AV node, ensuring coordination between the atria and ventricles?

Internodal pathway Signup and view all the answers

What is the role of the SA node in the heart's electrical conduction system?

SA node is the normal pacemaker of the heart. Signup and view all the answers

Describe the pathway of the interatrial pathway in the heart's electrical conduction system.

The interatrial pathway extends from the SA node within the right to the left atrium. Signup and view all the answers

What is the function of the AV node in cardiac excitation?

AV node serves as the only point of electrical contact between the atria and ventricles. Signup and view all the answers

How does the delay at the AV node impact the heart's electrical conduction system?

The delay at the AV node allows atrial contraction to be completed before ventricular excitation begins. Signup and view all the answers

Explain the significance of the Bundle of His in the heart's electrical conduction system.

The Bundle of His is responsible for relaying signals from the AV node to the Purkinje fibers. Signup and view all the answers

What is the primary function of Purkinje fibers in the heart?

Purkinje fibers are specialized for electrical conduction in the heart. Signup and view all the answers

How do Ca2+ sparks contribute to excitation-contraction coupling in cardiac muscle cells?

Ca2+ sparks lead to a much larger release of Ca2+ from the sarcoplasmic reticulum, inducing muscle contraction. Signup and view all the answers

What is the primary function of long-lasting Ca2+ channels in contractile cells?

Long-lasting Ca2+ channels in T tubules allow Ca2+ to enter the cytosol, leading to a larger Ca2+ release. Signup and view all the answers

Explain the concept of electrical excitation-contraction coupling between cardiac and skeletal muscle.

Electrical excitation in cardiac muscle must be complete before contraction begins to ensure coordinated function. Signup and view all the answers

What is the significance of the coordinated excitation between the atria and ventricles in the heart?

Coordinated excitation ensures that atrial contraction is complete before ventricular contraction begins. Signup and view all the answers

The SA node is responsible for delaying the signals to move to the Bundle of His.

False Signup and view all the answers

The interatrial pathway extends from the SA node within the right atrium to the left atrium.

True Signup and view all the answers

Excitation of the ventricles should be complete before atrial excitation occurs for proper cardiac function.

False Signup and view all the answers

The primary function of Purkinje fibers is to act as the normal pacemaker of the heart.

False Signup and view all the answers

During the refractory period, cardiac cells experience a period of increased excitability.

False Signup and view all the answers

Cardiovascular physiology

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Questions and Answers

What is the main function of Purkinje fibers in the heart?

Which phase in the cardiac contractile cells is characterized by a much larger release of Ca2+ known as Ca2+ sparks?

What is the unique feature of the membrane potential in cardiac contractile cells during the plateau phase?

Which component of an ECG represents the ventricular repolarization phase?

What event in the heart causes the 'dub' sound in the cardiac cycle?

Which condition is characterized by disorganized and chaotic contraction of the ventricles?

What type of cells in the heart muscle are responsible for generating the pulse that causes contractions?

Which type of nerve uses acetylcholine to bind to muscarinic receptors in the atria and slow the heart down?

What is the main ion movement responsible for giving rise to the pacemaker potential in autorhythmic cells?

What percentage of cardiac muscle cells do Contractile cells make up?

Which type of nerve uses noradrenaline and adrenaline to increase heart rate by binding to beta receptors of atria and ventricles?

Where are most of the long-lasting Ca2+ channels located in contractile cells?

What stimulates the opening of ryanodine receptor Ca2+ channels located on the sarcoplasmic reticulum?

What distinguishes Autorhythmic cells from Contractile cells?

Which of the following is not part of the normal electrical conduction pathway in the heart?

What is the function of the AV node in the heart's electrical conduction system?

Which structure in the heart is known as the normal pacemaker?

What is the primary role of Purkinje fibers in the heart?

What is the role of autorhythmic cells in the heart?

Which ion movement is essential for the pacemaker potential in autorhythmic cells?

During which phase do contractile cells of the heart display pacemaker activity?

What is the primary function of the autonomic nervous system in cardiac muscle excitation?

Which type of nerve is responsible for slowing down the heart rate by binding to muscarinic receptors?

During which phase in the cardiac contractile cells is the membrane potential maintained close to the peak positive level, leading to a much larger release of Ca2+ known as Ca2+ sparks?

Which specialized conducting fibers in the heart are larger than cardiomyocytes, have fewer myofibrils, and a large number of mitochondria, allowing for synchronized contractions of the ventricles?

Which electrical structure in the heart transmits electrical impulses from the AV node to the apex of the heart?

In cardiac excitation-contraction coupling, which ion's release from the sarcoplasmic reticulum induces muscle contraction in cardiac cells?

Which phase in cardiac contractile cells is characterized by the maintenance of a membrane potential close to peak positivity due to a higher release of Ca2+ and is unique to these cells?

What is the primary function of the AV node in the heart's electrical conduction system?

During which phase of the cardiac cycle does Ca2+ enter the cytosol from the T tubules stimulating the opening of Ca2+ channels on the sarcoplasmic reticulum?

Which component of the heart's electrical conduction system serves as the normal pacemaker and is responsible for generating the heart's electrical impulses?

What is the purpose of the delay that occurs at the AV node in the heart's electrical conduction system?

Which part of the heart's electrical conduction system extends from the SA node to the AV node, ensuring coordination between the atria and ventricles?

What is the role of the SA node in the heart's electrical conduction system?

Describe the pathway of the interatrial pathway in the heart's electrical conduction system.

What is the function of the AV node in cardiac excitation?

How does the delay at the AV node impact the heart's electrical conduction system?

Explain the significance of the Bundle of His in the heart's electrical conduction system.

What is the primary function of Purkinje fibers in the heart?

How do Ca2+ sparks contribute to excitation-contraction coupling in cardiac muscle cells?

What is the primary function of long-lasting Ca2+ channels in contractile cells?

Explain the concept of electrical excitation-contraction coupling between cardiac and skeletal muscle.

What is the significance of the coordinated excitation between the atria and ventricles in the heart?

The SA node is responsible for delaying the signals to move to the Bundle of His.

The interatrial pathway extends from the SA node within the right atrium to the left atrium.

Excitation of the ventricles should be complete before atrial excitation occurs for proper cardiac function.

The primary function of Purkinje fibers is to act as the normal pacemaker of the heart.

During the refractory period, cardiac cells experience a period of increased excitability.

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