Questions and Answers
What is the Intrinsic Conduction System?
This system sets the basic rhythm of the beating of the heart. It consists of autorhythmic cardiac cells that initiate and distribute impulses throughout the heart.
What is the function of the SA node?
Generates impulses about 75 times per minute; sets the pace for the entire heart.
What is the role of the Internodal pathway?
Carries impulses from the SA node to the AV node.
What happens at the AV node?
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Where is the AV bundle located and what is its importance?
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What are the Bundle branches responsible for?
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What are Purkinje Fibers?
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What is the pathway of depolarization in the heart?
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What does a normal ECG wave tracing include?
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What does the P wave represent on an ECG?
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What does the QRS complex represent on an ECG?
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What does the T wave represent on an ECG?
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What is hidden in the QRS complex during an ECG?
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What occurs in a left bundle branch block?
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What is tachycardia?
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Study Notes
Intrinsic Conduction System
- Comprises auto-rhythmic cardiac cells that regulate the heart's rhythm through impulses (action potentials).
- Responsible for initiating and distributing electrical signals across the heart.
SA Node
- Located in the right atrial wall near the superior vena cava entrance.
- Functions as the primary pacemaker, generating approximately 75 impulses per minute.
Internodal Pathway
- Conducts impulses from the SA node to the AV node.
- Ensures timely transmission of electrical signals.
AV Node
- Found in the inferior part of the interatrial septum, above the tricuspid valve.
- Briefly delays each impulse, allowing the atria to contract before the ventricles.
AV Bundle (Bundle of His)
- Located in the inferior interatrial septum; singular electrical connection between atria and ventricles.
- Critical for the coordinated contraction of the heart chambers.
Bundle Branches
- Two branches that extend from the AV bundle, running down the interventricular septum.
- Transmit impulses to the ventricles efficiently.
Purkinje Fibers
- Fibers that extend through the interventricular septum and into the heart apex, then branch into ventricular walls.
- Conduct impulses rapidly throughout the ventricles, facilitating synchronized contraction.
Pathway of Depolarization
- Sequence: SA node → Internodal pathway → AV node → Bundle branches → Purkinje fibers.
- Electrical events (action potentials) lead to mechanical events (contraction) resulting in a heartbeat.
Normal ECG Wave Tracing
- Comprises three main components: P wave, QRS complex, and T wave.
P Wave
- Represents atrial depolarization; occurs as the depolarization wave moves from the SA node through the atria.
- Duration is approximately 0.08 seconds, followed by atrial contraction.
QRS Complex
- Reflects ventricular depolarization; atrial repolarization occurs simultaneously.
- Lasts about 0.08 seconds and directly precedes ventricular contraction.
T Wave
- Indicates ventricular repolarization; occurs after ventricular contraction.
- Duration is approximately 0.16 seconds, leading to ventricular relaxation.
Hidden Atrial Depolarization
- Atrial depolarization is masked within the QRS complex, followed by atrial relaxation.
Left Bundle Branch Block
- Impulse conduction is delayed in the left ventricle, causing prolonged QRS complex.
- Result of slower cell-to-cell transmission compared to the bundle branches and Purkinje fibers.
Tachycardia
- Defined as an abnormally fast heart rate exceeding 100 beats per minute.
- Causes may include high body temperature, stress, medications, or heart disease.
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Description
Explore the fundamental concepts of the intrinsic conduction system of the heart with this interactive flashcard quiz. Learn about key components such as the SA node and how they contribute to the heart's rhythm. Perfect for students studying cardiac physiology.
