Quiz on Pacemaker Cells and Intrinsic Conduction System

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