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WorksheetsQuiz on Pacemaker Cells and Intrinsic Conduction System
Total questions: 15
Worksheet time: 8mins
What is the initial event in the pacemaker potential?
Opening of cation leak channels
Closing of calcium channels
Opening of sodium channels
Closing of potassium channels
What happens at the threshold of pacemaker cells?
Voltage-gated sodium channels open
Voltage-gated potassium channels open
Cation leak channels close
Voltage-gated calcium channels open
What is the role of voltage-gated calcium channels in pacemaker cells?
They close cation leak channels
They maintain resting potential
They cause depolarization
They cause repolarization
What triggers the opening of voltage-gated potassium channels?
Hyperpolarization of the cell
Reaching the threshold potential
Opening of sodium channels
Closing of calcium channels
What is the result of potassium flowing out of the cell?
Depolarization
Repolarization
Hyperpolarization
Threshold potential
What happens after the efflux of potassium in pacemaker cells?
The cell becomes inactive
The cell reaches threshold
The cell hyperpolarizes
The cell depolarizes
What is the function of the intrinsic conduction system?
To regulate heart rate
To ensure the heart beats as a functional syncytium
To contract the heart muscles
To maintain blood pressure
What is the role of the sinoatrial (SA) node?
To open calcium channels
To generate the initial impulse
To delay the impulse
To contract the ventricles
What occurs after atrial muscle depolarization?
Ventricular contraction
Impulse generation at the SA node
Repolarization of the atria
Atrial muscle contraction
What is the critical delay at the atrioventricular (AV) node for?
To close calcium channels
To open potassium channels
To initiate atrial contraction
To allow ventricular filling
What follows the critical delay at the AV node?
SA node impulse generation
Atrial contraction
Rapid conduction to the ventricular apex
Ventricular repolarization
What is the direction of ventricular contraction?
From base to apex
From apex upward
From left to right
From right to left
What ensures the heart beats as a functional syncytium?
The contraction of atrial muscles
A network of electrically connected cells
The opening of calcium channels
The closing of potassium channels
What is the role of cation leak channels in pacemaker cells?
To close calcium channels
To initiate repolarization
To maintain the pacemaker potential
To cause depolarization
What happens when voltage-gated Ca²⁺ channels close?
Potassium channels open
Sodium channels open
The cell depolarizes
Cation leak channels close
