A&P 2 cardiac conduction system and ECG study guide
This study guide covers the cardiac conduction system and electrocardiogram (ECG) principles, essential for understanding heart function and rhythm in physiology courses.
Quiz(56 questions)
1. What phase of the cardiac cycle occurs when the heart chambers are filling with blood?
Terms in this Study Set(56)
Cardiac Conduction System(16)
Sinoatrial (SA) Node
The primary pacemaker of the heart, setting the rhythm for heartbeats by generating electrical impulses.
Atrioventricular (AV) Node
Serves as a gatekeeper, delaying impulses from the SA node before sending them to the ventricles.
Bundle of His
A pathway for electrical signals to travel from the AV node to the ventricles through the interventricular septum.
Purkinje Fibers
Specialized fibers that distribute the electrical impulse throughout the ventricles, causing them to contract.
True or False: The SA node is responsible for the heart's electrical delay.
False. The AV node is responsible for the delay.
What happens when the SA node fails?
The AV node may take over, but at a slower rate (40-60 beats per minute).
Impulse pathway order
SA Node → AV Node → Bundle of His → Purkinje Fibers.
Electrocardiogram (ECG)
A graphical representation of the electrical activity of the heart, used to diagnose arrhythmias.
Atrial Contraction Trigger
The electrical impulse from the SA node causes the atria to contract and push blood into the ventricles.
Ventricular contraction initiation
Signals from the AV node spread through the Bundle of His and Purkinje fibers, leading to ventricular contraction.
Effect of sympathetic stimulation
Increases heart rate and force of contraction by enhancing conduction through the AV node.
Filling the blank: The heart's conduction system allows for _____ coordination.
synchronized
Comparison: SA Node vs AV Node
SA Node is the primary pacemaker; AV Node is the secondary, with a slower intrinsic rate.
Heart Rate Regulation
The autonomic nervous system adjusts heart rate by modulating impulses from the SA node.
True or False: Purkinje fibers slow down the conduction of impulses.
False. Purkinje fibers rapidly conduct impulses to ensure efficient ventricular contraction.
Cause → Effect: AV Node Block
Causes delayed impulse transmission leading to irregular heart rhythms or missed beats.
Electrocardiogram (ECG) Basics(20)
What does ECG stand for?
ECG stands for Electrocardiogram, a test that records the electrical activity of the heart.
True or False: ECG measures heart's blood flow.
False. ECG measures the electrical activity, not blood flow.
Describe the P wave.
The P wave represents atrial depolarization, indicating atrial contraction.
What does the QRS complex represent?
The QRS complex reflects ventricular depolarization, leading to ventricular contraction.
Fill in the blank: The _______ segment shows the period between ventricular depolarization and repolarization.
ST segment.
What does the T wave indicate?
The T wave indicates ventricular repolarization, the recovery phase after contraction.
Comparison: P wave vs. T wave.
P wave: Atrial depolarization. T wave: Ventricular repolarization.
What is heart rate calculated from ECG?
Heart rate can be calculated as: .
True or False: An ECG can diagnose heart attacks.
True. ECG can show patterns indicating ischemia or myocardial infarction.
Describe the significance of the QT interval.
The QT interval represents the time for ventricular depolarization and repolarization, indicating electrical stability.
What does an elevated ST segment indicate?
An elevated ST segment can suggest acute myocardial injury or strain.
Fill in the blank: A prolonged QT interval may lead to _______.
arrhythmias.
Explain the significance of the R-R interval.
The R-R interval is crucial for determining heart rate and rhythm regularity.
Comparison: Normal vs. abnormal ECG.
Normal ECG: Consistent waveforms. Abnormal ECG: Irregularities, e.g., extra beats.
What is the purpose of lead placement in ECG?
Lead placement affects the view of the heart's electrical activity, aiding diagnosis.
True or False: All leads measure the same electrical activity.
False. Different leads capture variations in electrical activity from different angles.
What does a U wave represent?
The U wave may represent the repolarization of the Purkinje fibers; significance varies.
Describe the role of the baseline in ECG.
The baseline indicates the isoelectric line, essential for assessing wave amplitude.
What is the clinical significance of a flat T wave?
A flat T wave may indicate electrolyte imbalances or ischemia.
Explain how to identify atrial fibrillation on an ECG.
Atrial fibrillation shows irregular R-R intervals and absence of distinct P waves.
Cardiac Cycle and Heart Rhythm(20)
Define the cardiac cycle.
The cardiac cycle refers to the sequence of events in one heartbeat, including diastole and systole phases.
What occurs during diastole?
During diastole, the heart muscles relax, and the chambers fill with blood. This phase is crucial for maintaining blood flow.
What happens during systole?
Systole is when the heart muscles contract, pumping blood out of the chambers into the arteries.
Describe atrial contraction.
Atrial contraction occurs at the end of diastole, pushing remaining blood into the ventricles, contributing to ventricular filling.
True or False: The heart has a resting phase.
False. The heart does not have a resting phase; it continuously cycles through contraction and relaxation.
In what order do the heart chambers contract?
The atria contract first, followed by the ventricles; this sequence ensures efficient blood flow.
Normal heart rhythm is called what?
Normal heart rhythm is termed 'sinus rhythm,' originating from the sinoatrial (SA) node in the right atrium.
What is arrhythmia?
Arrhythmia is an abnormal heart rhythm resulting from issues in the heart's electrical conduction system, affecting heart rate.
Fill in the blank: During ________, the heart is filled with blood.
During diastole, the heart is filled with blood.
What is the significance of the P wave?
The P wave on an ECG represents atrial depolarization, indicating the electrical activation of the atria.
Compare bradycardia and tachycardia.
Bradycardia is a slow heart rate (below 60 bpm), while tachycardia is a fast heart rate (above 100 bpm).
Cause → Effect: Atrial fibrillation.
Cause: Irregular electrical signals; Effect: Inefficient blood pumping, increasing stroke risk.
What is the role of the AV node?
The AV node delays the electrical signal from the atria before transmitting it to the ventricles, allowing for coordinated contraction.
Describe the QRS complex.
The QRS complex on an ECG represents ventricular depolarization, indicating the electrical activation of the ventricles.
Normal range for resting heart rate?
The normal resting heart rate for adults ranges from 60 to 100 beats per minute.
True or False: Ventricular systole follows atrial systole.
True. Ventricular systole occurs after atrial systole, ensuring efficient blood ejection from the heart.
What is the T wave?
The T wave indicates ventricular repolarization, which is the recovery phase after ventricular contraction.
Identify one consequence of tachycardia.
One consequence of tachycardia can be reduced cardiac efficiency and potential heart fatigue due to decreased filling time.
What does the ST segment represent?
The ST segment on an ECG represents the period between ventricular depolarization and repolarization, indicating a brief pause in electrical activity.
What occurs during isovolumetric contraction?
During isovolumetric contraction, the ventricles contract with closed valves, causing pressure to rise without any change in volume.
Questions in this Study Set(56)
1. What phase of the cardiac cycle occurs when the heart chambers are filling with blood?
2. What is the primary function of the Sinoatrial (SA) Node?
3. What does the term 'electrical axis' refer to in an ECG?
4. During which phase does the heart pump blood out to the arteries?
5. The Atrioventricular (AV) Node primarily functions as what?
6. Which of the following statements is true regarding the P-R interval?
7. Which of the following correctly describes ventricular systole?
8. Which structure provides the pathway for electrical signals to travel from the AV Node to the ventricles?
9. In an ECG, what does a negative deflection in the QRS complex indicate?
10. What is the first electrical event that occurs in the heart during the cardiac cycle?
11. What role do Purkinje Fibers play in the cardiac conduction system?
12. What does the ST segment represent in an ECG?
13. Which heart rhythm indicates a normal heart activity?
14. True or False: The SA node is responsible for delaying electrical impulses in the heart.
15. Which of the following best describes a normal T wave?
16. What occurs during isovolumetric relaxation?
17. When the SA Node fails, what is likely to happen?
18. Which of the following conditions would likely cause an elevated ST segment?
19. Which of the following is NOT a component of the cardiac cycle?
20. What is the correct order of the cardiac conduction pathway?
21. How can you identify ventricular tachycardia on an ECG?
22. In a heart rate of 80 beats per minute, which phase lasts the longest?
23. What does an Electrocardiogram (ECG) represent?
24. What does the QT interval indicate in an ECG?
25. What does the T wave on an ECG signify?
26. What triggers atrial contraction in the heart?
27. What does a flat baseline in an ECG indicate?
28. True or False: The heart has distinct phases of contraction and relaxation.
29. How does the AV Node affect ventricular contraction?
30. Which of the following is NOT a part of the cardiac conduction system?
31. What is the significance of the P wave on an ECG?
32. What is the effect of sympathetic stimulation on heart function?
33. What does the presence of a U wave in an ECG potentially indicate?
34. What does an extended PR interval on an ECG indicate?
35. Fill in the blank: The heart's conduction system allows for _____ coordination.
36. What does it mean if the R-R interval is constant?
37. In bradycardia, the heart rate is typically below what value?
38. Which of the following is NOT true about the SA Node and AV Node?
39. Which waveform represents the time between atrial and ventricular depolarization?
40. Which of the following accurately describes the AV node's function?
41. What is the result of an AV Node block?
42. When viewing an ECG, what does a prolonged QT interval suggest?
43. What is a common consequence of tachycardia?
44. Why are Purkinje Fibers important for the ventricles?
45. What is the primary purpose of placing electrodes in specific locations for an ECG?
46. During which event does the heart experience maximum pressure in the ventricles?
47. Which structure serves as a gatekeeper by delaying electrical impulses before they reach the ventricles?
48. Which of the following ECG features is associated with atrial fibrillation?
49. What does the ST segment on an ECG represent?
50. How can you determine heart rate from an ECG strip?
51. What is the role of the sinoatrial (SA) node?
52. What does a notched P wave usually indicate?
53. Which of the following describes atrial contraction during the cardiac cycle?
54. Which of the following best describes the significance of the R-R interval in an ECG?
55. Which of the following is NOT true about sinus rhythm?
56. Which of the following is NOT typically included in a standard ECG?
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