Question 1

A health care provider who suspects that a patient is having a heart attack will look very carefully at this portion of the ECG.

Accepted Answer

The S-T segment on an ECG is closely monitored in the context of a suspected heart attack (myocardial infarction) because changes or elevation in this segment can indicate ischemia or damage to the heart muscle.

Question 2

This portion of the ECG is associated with ventricular contraction.

Accepted Answer

A

Question 3

During exercise, the heart rate _________.

Accepted Answer

During exercise, the heart rate increases in proportion to the level of exertion involved to meet the increased demand for oxygen and nutrients by the muscles.

Question 4

In sequential order, the components of the intrinsic conduction system, beginning at the SA node, are_________ .

Accepted Answer

The correct sequence for the components of the intrinsic conduction system of the heart, starting from the SA node, is: AV node, AV bundle (bundle of His), bundle branches, and finally the subendocardial conducting network (Purkinje fibers). This pathway ensures the orderly and coordinated contraction of the heart chambers.

Question 5

Bradycardia describes a heart rate of_________ .

Accepted Answer

Bradycardia is defined as a heart rate that is slower than normal, specifically less than 60 beats per minute.

Question 6

The T wave of the ECG represents_________ .

Accepted Answer

The T wave on an electrocardiogram (ECG) represents the repolarization of the ventricles, which is the process of the ventricles returning to their resting state after having contracted.

Question 7

The QRS complex is associated with _________.

Accepted Answer

The QRS complex represents the depolarization of the ventricles, which leads to ventricular contraction.

Question 8

In the normal heart, the _________has the highest rate of discharge and sets the rate of depolarization for the heart as a whole.

Accepted Answer

The SA (sinoatrial) node has the highest rate of discharge among the components listed and is responsible for setting the pace of depolarization for the entire heart, acting as the heart's natural pacemaker.

Question 9

If the AV node is damaged so that it can no longer transmit the signal from the SA node (total heart block), will the ventricles continue to contract? Why or why not?

Accepted Answer

In the case of total heart block, where the AV node is damaged and cannot transmit signals from the SA node, the ventricles can still contract. This is because the Purkinje fibers and the bundle of His, which are part of the intrinsic cardiac conduction system, can initiate impulses independently, albeit at a slower rate than the SA node. Therefore, while the ventricles will continue to contract, the rate will be slower, and the coordination between atrial and ventricular contractions will be lost.

Question 10

It the interval between R waves is on an ECG is 0.80 sec, then the heart rate is _________.

Accepted Answer

To calculate the heart rate from an ECG, you can use the formula: Heart Rate = 60 / R-R interval (in seconds). Given an R-R interval of 0.80 seconds, the calculation would be 60 / 0.80 = 75 beats per minute.

Question 11

The electrocardiogram (ECG)shows a record of .

Accepted Answer

The electrocardiogram (ECG) records the electrical activity of the heart muscle, which reflects the overall electrical events occurring in the heart.

Question 12

A normal Q- T interval is_________ .

Accepted Answer

The normal QT interval varies depending on heart rate, but a common reference range for a heart rate of around 70 beats per minute is approximately 0.32 to 0.38 seconds. This range can slightly vary based on different sources, but option A is within the accepted range for a normal QT interval at that heart rate. Options B, C, and D provide intervals that are either too long, too short, or not typically used to describe normal QT intervals.

Question 13

How does holding the breath affect heart rate?

Accepted Answer

The answer of How does holding the breath affect heart...

Question 14

Ventricular fibrillation is __________ _.

Accepted Answer

Ventricular fibrillation is characterized by rapid, uncoordinated contractions of the ventricles, which can lead to a lack of effective blood circulation and sudden cardiac death if not treated immediately.

Question 15

The middle and largest deflection wave in a normal ECG is the_________ .

Accepted Answer

The QRS complex represents ventricular depolarization, which is the largest and most prominent part of an ECG tracing, reflecting the electrical activity that leads to ventricular contraction.

Question 16

The function of the intrinsic conduction system is to_________ .

Accepted Answer

The intrinsic conduction system of the heart ensures that cardiac muscle cells contract in a coordinated manner, leading to efficient pumping of blood throughout the body. This system includes components like the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers, which work together to initiate and propagate electrical impulses across the heart.

Quiz 31: Conduction System of the Heart and Electrocardiography