Exploring Cardiac Conduction and Heart Function

What is the primary misconception about the use of defibrillators in cardiac arrest?

• They stop the heart to reset its rhythm

• They are used to monitor heart rate

• They restart a stopped heart

• They provide oxygen to the heart

What makes cardiac muscle cells resistant to fatigue?

• Their small size

• The presence of a single nucleus

• A high concentration of mitochondria

• Their ability to regenerate quickly

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What percentage of a cardiac cell is made up of mitochondria?

• 5 to 10 percent

• 40 to 50 percent

• 25 to 35 percent

• 10 to 15 percent

How are cardiac cells different from skeletal muscle cells in terms of connectivity?

• They are only electrically connected

• They are not connected at all

• They are only physically connected

• They are both physically and electrically connected

What is the role of pacemaker cells in the heart?

• To filter blood before it enters the heart

• To pump blood throughout the body

• To generate electrical impulses for a heartbeat

• To repair damaged heart tissue

What causes the membrane potential of pacemaker cells to drift toward its threshold?

• A decrease in cell size

• The presence of multiple nuclei

• External electrical stimulation

• Leaky sodium and potassium channels

What is the main function of the SA node in the heart?

• To close the heart valves

• To filter blood

• To initiate the heartbeat

• To serve as the heart's natural pacemaker

What is the purpose of the delay in the AV node during the cardiac cycle?

• To ensure the atria finish contracting before the ventricles contract

• To increase the heart rate

• To decrease blood pressure

• To allow the ventricles to contract first

How does a defibrillator help during fibrillation?

• By pumping blood manually

• By increasing the heart rate

• By stopping the chaotic electrical activity to reset the heart's rhythm

• By cooling down the heart

Why can't CPR correct fibrillation on its own?

• It can't generate electrical impulses

• It stops the heart

• It only works on healthy hearts

• It requires medication to work