Electrical Properties Of The Heart 2

Question 1

Describe the role of the special conducting system in the heart.

Answer 1

The special conducting system controls the coordinated depolarization and contraction of different parts of the heart, ensuring effective pumping of blood.

Question 2

Define the sinoatrial node and its function in the heart.

Answer 2

The sinoatrial node is a cluster of pacemaker cells in the heart that initiates the electrical impulse for heart contraction, making it the pacemaker for the rest of the heart.

Question 3

How does depolarization spread through the heart via gap junctions?

Answer 3

Depolarization spreads cell to cell through gap junctions, allowing for the wave of depolarization to move through the atria and then to the ventricles.

Question 4

Describe the role of the annulus fibrosis in the heart’s electrical conduction system.

Answer 4

The annulus fibrosis is a ring of non-conducting tissue that prevents immediate spread of depolarization from the atria to the ventricles, ensuring proper coordination of heart contractions.

Question 5

What is the function of the atrioventricular (AV) node in the heart’s electrical conduction system?

Answer 5

The AV node conducts electrical impulses very slowly, acting as a delay box to allow the atria to contract and fill the ventricles before ventricular contraction.

Question 6

Explain the significance of the rapid conduction system in the heart.

Answer 6

The rapid conduction system, including the bundle of His, ensures quick and synchronized depolarization of the ventricles, leading to a strong and coordinated contraction for effective blood circulation.

Question 7

Describe the difference in conduction speed between the sinoatrial node and the AV node.

Answer 7

The sinoatrial node conducts at about 0.5 m/s, while the AV node conducts at about 0.05 m/s, making it ten times slower than the sinoatrial node.

Question 8

Describe the process of electrical conduction the heart.

Answer 8

The electrical con in the heart starts the sinoatrial node depolarizing, spreading through the atria, then to the atrioventricular node bundle of His, Purkinje fibers, leading to ventricular contraction and relaxation.

Question 9

What is the significance of the Purkinje fibers in the heart’s electrical conduction system?

Answer 9

Purkinje fibers are specialized fibers that ensure coordinated contraction of the heart by rapidly conducting the electrical impulses to the ventricles.

Question 10

How is an electrocardiogram (ECG) generated from the heart’s electrical activity?

Answer 10

An ECG is generated by summing the small extracellular electrical potentials from multiple myocytes depolarizing and repolarizing simultaneously, creating larger electrical waves conducted through bodily fluids to the skin.

Question 11

Define the P wave, QRS complex, and T wave in an ECG.

Answer 11

The P wave represents atrial depolarization, the QRS complex signifies ventricular depolarization, and the T wave indicates ventricular repolarization.

Question 12

Describe the role of the atrioventricular node in the heart’s electrical conduction system.

Answer 12

The atrioventricular node acts as a delay box, allowing the atria to contract before the ventricles by slowing down the spread of depolarization from the atria to the ventricles.

Question 13

How can the transmembrane potential of a myocyte be measured?

Answer 13

The transmembrane potential of a myocyte can be measured by using intracellular recording with an electrode in the cytoplasm and another in the extracellular fluid, showing large changes in voltage during depolarization and repolarization.

Question 14

Describe the relationship between atrial repolarization and ventricular depolarization on an ECG.

Answer 14

Atrial repolarization occurs at the same time as ventricular depolarization, causing the atrial repolarization wave to be obscured within the QRS complex.

Question 15

What information can an ECG provide about the heart’s rhythm?

Answer 15

An ECG can provide information about the heart’s rhythm, showing the sequence of P waves, QRS complexes, and T waves in a normal sinus rhythm.

Question 16

Define sinus rhythm in the context of an ECG.

Answer 16

Sinus rhythm on an ECG refers to a normal heart rhythm where each P wave is followed by a QRS complex and then a T wave.

Question 17

How can the heart rate be calculated manually using an ECG?

Answer 17

The heart rate can be calculated by measuring the RR interval (number of boxes between two R waves) on the ECG paper, with each large square representing 0.2 seconds.

Question 18

Describe what a first-degree heart block looks like on an ECG.

Answer 18

In a first-degree heart block, the ECG appears normal but with a prolonged PR interval, indicating a delay in the conduction of the electrical signal from the atria to the ventricles.

Question 19

What is the significance of the PR interval in diagnosing heart block on an ECG?

Answer 19

The PR interval is crucial in diagnosing heart block as a prolonged PR interval indicates a delay in the conduction of the electrical signal from the atria to the ventricles.

Question 20

Explain the importance of ECG as a diagnostic tool in healthcare settings.

Answer 20

ECG is a valuable diagnostic tool due to its non-invasive nature, quick application, and ability to provide essential information about the heart’s conducting system and rhythm.

Question 21

How can the heart rate be determined using the information from an ECG paper?

Answer 21

The heart rate can be determined by counting the number of boxes between two R waves on the ECG paper, with each large square typically representing 0.2 seconds, allowing for manual calculation of heart rate in beats per minute.

Question 22

Describe 1st degree heart block an ECG.

Answer 22

In1st degree heart block, there is delayed conduction from the atria to the ventricles, resulting in a prolonged PR interval.

Question 23

What is Mobitz type 1 second degree heart block?

Answer 23

Mobitz type 1 second degree heart block is characterized by a progressive lengthening of the PR interval until a QRS complex is dropped.

Question 24

Define third degree heart block.

Answer 24

Third degree heart block, also known as complete heart block, is a condition where there is no atrioventricular conduction, leading to independent atrial and ventricular contractions.

Question 25

How is atrial flutter different from atrial fibrillation?

Answer 25

Atrial flutter is characterized by a rapid but organized atrial contraction with a sawtooth pattern on ECG, while atrial fibrillation involves uncoordinated atrial contractions.

Question 26

Describe the ECG pattern of atrial fibrillation.

Answer 26

Atrial fibrillation shows irregularly spaced P waves, with no clear P wave preceding each QRS complex, indicating chaotic atrial depolarization.

Question 27

What is the treatment for third degree heart block?

Answer 27

Third degree heart block, or complete heart block, can be treated by implanting an electrical pacemaker device into the heart to regulate the heartbeat.

Question 28

Describe ventricular fibrillation.

Answer 28

Ventricular fibrillation is when there is uncoordinated contraction in the ventricles, leading to ineffective pumping of blood and potential loss of consciousness.

Question 29

Define defibrillator.

Answer 29

A defibrillator is a device that delivers an electric shock to the heart to depolarize all cells simultaneously, allowing the sinoatrial node to restart the heart’s normal rhythm.

Question 30

How does a defibrillator work in the heart?

Answer 30

A defibrillator depolarizes all heart cells simultaneously, putting them in a refractory period, which gives the sinoatrial node a chance to reestablish the heart’s normal rhythm.

Question 31

Do ventricular fibrillation and atrial fibrillation have the same implications for the heart?

Answer 31

No, ventricular fibrillation is more serious as it affects the ventricles’ ability to pump blood effectively, leading to potential unconsciousness and requiring immediate defibrillation.

Question 32

Describe the role of the sinoatrial node in the heart.

Answer 32

The sinoatrial node is the heart’s natural pacemaker, initiating the electrical impulses that coordinate heart contractions. It has the fastest pacemaker cells in the heart.

Question 33

What is the significance of recognizing different types of arrhythmias in medical practice?

Answer 33

Recognizing different arrhythmias is crucial for appropriate treatment and management, as each type may require specific interventions to prevent complications like ventricular fibrillation.

Question 34

How does ventricular fibrillation impact oxygen delivery to the body?

Answer 34

Ventricular fibrillation disrupts the coordinated pumping of the heart, leading to inadequate blood circulation and oxygen delivery to vital organs like the brain, potentially causing unconsciousness.

Question 35

Describe the process of depolarization in the heart during a normal rhythm.

Answer 35

During a normal heart rhythm, depolarization starts at the sinoatrial node, spreading electrical impulses through the atria, then to the ventricles, leading to coordinated contractions for effective blood pumping.

Question 36

Describe 2nd degree heart block.

Answer 36

2nd degree heart block is characterized by a longer delay between the atria contracting and the ventricles contracting, leading to a gradual increase in the PR interval.

Question 37

Define right bundle branch block.

Answer 37

Right bundle branch block is a condition where there is a problem with the depolarisation spreading through the bundle of His and Purkinje fibers on the right side of the heart.

Question 38

How does atrial flutter differ from atrial fibrillation?

Answer 38

Atrial flutter is when the atria depolarize and contract much faster than normal, while atrial fibrillation is the uncoordinated contraction of the atria due to pacemaker failure.

Question 39

Do you know what left anterior hemiblock refers to?

Answer 39

Left anterior hemiblock is a condition where there is a problem with the depolarisation spreading to the front of the heart.

Question 40

Describe the difference between left bundle branch block and right bundle branch block.

Answer 40

Left bundle branch block and right bundle branch block both involve issues with depolarisation spreading through the bundle of His and Purkinje fibers, but left bundle branch block affects the left side of the heart while right bundle branch block affects the right side.

Question 41

What is the purpose of defibrillation in the context of arrhythmias?

Answer 41

Defibrillation is used to shock the heart, causing all cells to depolarize simultaneously and enter their refractory periods, allowing a pacemaker to restore the heart to sinus rhythm.