Week 3 - Arrthymias Flashcards
What is automaticity in the context of the heart?
Automaticity is the heart’s ability to generate its own action potential, or heart rate, without external nerve signals.
What are autorhythmic cells in the heart?
Autorhythmic cells are specialized cardiac cells that can generate spontaneous electrical impulses, enabling the heart to contract without nerve stimulation.
What is the function of the SA node?
The SA node (Sinoatrial Node) is the pacemaker of the heart and initiates electrical impulses, setting the regular rhythm (sinus rhythm) of the heart.
How does depolarization change the charge of the cardiac cell?
During depolarization, Na ions enter the cell, reversing the charge (negative outside, positive inside), which creates electrical energy for contraction.
What is the role of the AV node in the heart?
The AV node (Atrioventricular Node) is the gateway to the ventricles, transmitting electrical impulses from the atria to the ventricles.
What is the path of the electrical impulse in the heart?
The impulse starts in the SA node, travels to the AV node, through the bundle of His, down the bundle branches, and finally to the Purkinje fibres.
How do action potentials work in the heart?
Action potentials involve the movement of ions like Na, K, and Ca, which create electrical energy, leading to contraction of the heart muscle.
How is the heart’s conduction system different from other muscles?
The heart’s conduction system contains specialized cells that generate and transmit action potentials without needing stimulation from the nervous system.
What is the cardiac cycle?
The cardiac cycle involves a synchronous contraction cycle, including systole and diastole, driven by the transmission of electrical impulses through the myocardium.
What does the SA node do regarding heart rate?
The SA node sets the regular rhythm of the heart, known as sinus rhythm, and is influenced by both sympathetic and parasympathetic nerve fibers.
What happens in Phase 0 of the cardiac action potential?
Phase 0 is the rapid depolarization, where sodium ions flow into the cell, initiating electrical activity.
What is the refractory period in the cardiac cycle?
The refractory period prevents new action potentials from being initiated and allows time for the heart to fill with blood.
What occurs in Phase 1 of the cardiac action potential?
In Phase 1, there is a brief repolarization with the outward flow of potassium.
In Phase 1, there is a brief repolarization with the outward flow of potassium.
Describe the Plateau phase (Phase 2) of the cardiac action potential.
In Phase 2, calcium flows into the cell, influencing myocardial contractile strength and stroke volume.
What happens during Phase 3 of the cardiac action potential?
In Phase 3, potassium exits the cell, resulting in rapid repolarization of the cell.
What does Phase 4 represent in the cardiac action potential?
Phase 4 represents the resting membrane potential where the cell is prepared for the next action potential.
What does the P wave on an ECG represent?
The P wave represents atrial depolarization.
What does the QRS complex on an ECG show?
The QRS complex represents ventricular depolarization and atrial repolarization.
What does the PR interval represent on an ECG?
The PR interval measures the time from the onset of atrial activation (P wave) to the onset of ventricular activation (beginning of QRS).
What is indicated by the T wave on an ECG?
The T wave represents ventricular repolarization.
How does the cardiac conduction system ensure coordinated heartbeats?
The electrical impulse follows a coordinated path from the SA node to the Purkinje fibres, which initiates heart contraction and maintains systole and diastole.
What are arrhythmias?
Arrhythmias are abnormalities in heart rhythm, ranging from occasional missed beats or rapid beats to serious disturbances that impair the heart’s pumping ability, potentially causing heart failure or death.
What are the different types of arrhythmias?
Arrhythmias can be classified as:
- Sinus rhythms: Bradycardia, Tachycardia
- Atrial rhythms: Atrial flutter, Atrial fibrillation
- Ventricular rhythms: Ventricular tachycardia, Ventricular fibrillation (most fatal)
What are the types of impulse conduction disorders?
The types include:
- First degree heart block
- Second degree heart block (Mobitz I or Wenckebach)
- Second degree heart block (Mobitz II)
- Third degree heart block
What is Atrial fibrillation?
Atrial fibrillation is the most common arrhythmia, and preventing complications like blood clotting, pulmonary embolism, and embolic strokes is essential.
What can cause alterations in cardiac conduction?
Potential causes include:
- Electrolyte disturbances
- Myocardial ischemia
- Acute myocardial infarction
- Drug therapy
- Intrinsic problems of autorhythmic cells
What are the life-threatening arrhythmias?
The life-threatening arrhythmias include:
- Ventricular tachycardia
- Ventricular fibrillation
- Asystole
- Pulseless electrical activity
- Third degree heart block
What happens in cardiorespiratory arrest due to arrhythmias?
The heart either stops contracting or has abnormal activity, resulting in no cardiac output, and breathing cessation usually accompanies it.
How are life-threatening arrhythmias managed?
Immediate life support is essential to manage these arrhythmias effectively.
