Question 1

The inherent rate of the AV junction is ________ bpm.

Accepted Answer

The inherent rate of the AV (Atrioventricular) junction, which includes the AV node and the bundle of His, is 40-60 beats per minute (bpm). This rate comes into play when the AV junction acts as the pacemaker, typically in situations where the sinoatrial (SA) node fails to set the rhythm or its impulses are blocked.

Question 2

If polarizing is considered the ready state,then ________ would be considered the recovery state.

Accepted Answer

Repolarization is the recovery state as it is the process by which the cell membrane returns to its resting state after depolarization. During depolarization, the cell membrane potential becomes more positive due to the influx of positive ions, while during repolarization, the membrane potential becomes negative again due to the efflux of positive ions. Therefore, repolarization is the opposite process of depolarization and represents the recovery state.

Question 3

Which cardiac cells are responsible for initiating and conducting pacemaker impulses?

Accepted Answer

Electrical cells, specifically the sinoatrial (SA) node, are responsible for initiating and conducting pacemaker impulses in the heart. These cells have unique properties which allows them to depolarize spontaneously and at a faster rate compared to other cardiac cells.

Question 4

What term is used to refer to the process of electrical discharge and the flow of electrical activity?

Accepted Answer

Depolarization is the term used to refer to the process of electrical discharge and the flow of electrical activity. Repolarization refers to the return of the electrical charge back to its resting state, while polarization refers to the initial establishment of an electrical charge difference between two points. Polarized refers to an object or substance that has an electrical charge imbalance.

Question 5

After leaving the area of the AV node,impulses go through the ________ to reach the right and left bundle branches.

Accepted Answer

After leaving the AV node, impulses pass through the Bundle of His to reach the right and left bundle branches, which then spread into the Purkinje fibers, allowing for rapid and coordinated contraction of the ventricles. Therefore, the best choice is B.

Question 6

What is the term for the fail-safe mechanism that allows a lower pacemaker to take over when a higher site fails?

Accepted Answer

The term for the fail-safe mechanism that allows a lower pacemaker to take over when a higher site fails is called "escape". When the higher pacemaker (such as the SA node) fails, a lower pacemaker (such as the AV node or ventricles) can take over and generate a slower heart rate. This is known as an escape rhythm.

Question 7

Which of the following does NOT happen when the sympathetic branch is stimulated?

Accepted Answer

Stimulation of the sympathetic branch typically leads to an increase in heart rate and an increase in ventricular contractility due to increased release of norepinephrine. This can also lead to a decrease in the time it takes for impulses to travel through the AV node, speeding up the heart's electrical activity. However, ventricular conduction typically does not slow down during sympathetic stimulation.

Question 8

When stimulated,the ________ branch of the nervous system increases heart rate,AV conduction,and irritability.

Accepted Answer

The sympathetic branch of the nervous system is responsible for increasing heart rate, AV conduction, and irritability. It is the "fight or flight" response of the body and prepares the body for physical activity or stress. The parasympathetic branch, on the other hand, has the opposite effect and slows down heart rate and conduction. The pacemaker and inherent options are not related to the question.

Question 9

The inherent rate of the ventricle is ________ bpm.

Accepted Answer

The inherent rate of the ventricle is 20-40 beats per minute (bpm), which reflects the rate at which the ventricular pacemaker cells (Purkinje fibers) can generate impulses on their own.

Question 10

Part of the parasympathetic branch of the autonomic nervous system is the ________ nerve.

Accepted Answer

The vagus nerve is a part of the parasympathetic branch of the autonomic nervous system, playing a crucial role in controlling heart rate, gastrointestinal peristalsis, sweating, and other functions.

Question 11

The built-in rate of each of the three major areas of the conduction system is referred to as the ________ rate.

Accepted Answer

The built-in rate of the conduction system is referred to as the inherent rate. The other options (fast, heart, and escape) do not accurately describe the rate of the conduction system.

Question 12

Which of the following best explains the mechanism called irritability?

Accepted Answer

Irritability refers to the ability of a subsidiary pacemaker site (such as the atrioventricular node or Purkinje fibers) to initiate an impulse and take over control of the heartbeat from the normal pacemaker (the sinoatrial node). Therefore, option C – where a lower pacemaker site speeds up to take control of the heart – best explains the mechanism of irritability.

Question 13

Which of the following is NOT a part of the normal cardiac conduction system?

Accepted Answer

The coronary sinus is a vein that collects deoxygenated blood from the heart's veins and returns it to the right atrium. It is not part of the normal cardiac conduction system that regulates the heart's electrical activity. The AV node, Purkinje fibers, and internodal pathways are all essential components of the cardiac conduction system.

Question 14

Which is the normal pacemaker of the heart?

Accepted Answer

The SA (sinoatrial) node is located in the right atrium of the heart and is considered the normal pacemaker of the heart. It initiates each heartbeat and sets the rhythm for the rest of the heart. The other options (B, C, and D) are also involved in the electrical conduction of the heart, but they are not considered the normal pacemaker.

Question 15

The inherent rate of the SA node is ________ bpm.

Accepted Answer

The SA node has an inherent rate of 60-100 bpm (beats per minute).

Quiz 1: Electrophysiology