20 Questions
What is the resting membrane potential of a cardiomyocyte?
-90 millivolts
What is the cardiac pacemaker potential?
An action potential in the electrical conduction system of the heart
What are the three channels of interest in the cardiac action potential?
fast sodium channels, potassium channels, and L-type voltage-gated calcium channels
What are the two separate action potentials to consider in the heart?
The pacemaker potential and the cardiac action potential
What is responsible for the depolarization phase in the cardiac action potential?
the rapid influx of sodium ions
Which part of the heart does the pacemaker potential apply to?
The sinoatrial node
Which channels open after sodium channels close during the cardiac action potential?
L-type calcium channels
What are the three types of voltage-gated channels that the pacemaker potential relies on?
Sodium, calcium, and potassium
When does the sodium channel automatically open during the pacemaker potential?
During the pre-potential phase
What is the plateau phase in the cardiac action potential due to?
the balance between calcium influx and potassium efflux
What happens when the calcium channel opens during the pacemaker potential?
It leads to rapid depolarization
What does the plateau phase allow the chamber to do during the cardiac action potential?
continue pumping blood efficiently
When does the potassium channel open during the pacemaker potential?
During repolarization
What happens to calcium channels and potassium channels during repolarization in the cardiac action potential?
calcium channels close and potassium channels remain open
What brings the cardiomyocyte back to resting membrane potential during the cardiac action potential?
repolarization phase
Why is the pacemaker potential an unstable membrane potential?
To allow the heart to remain autorhythmic
What can stimulate another action potential in adjacent cardiomyocytes or cells of the electrical conduction system?
influx of sodium ions
Does the heart's autorhythmicity require nervous system input?
No, it does not require nervous system input at all
Which of the following ions is not mentioned as part of the cardiac action potential?
chloride ions
How does the vagus nerve affect heart rate?
It decreases the heart rate by increasing the distance between peaks in the pacemaker potential
Study Notes
- The video is about the cardiomyocyte or cardiac action potential.
- The resting membrane potential of a cardiomyocyte is around -90 millivolts.
- There are three channels of interest: fast sodium channels, potassium channels, and L-type voltage-gated calcium channels.
- The depolarization phase is due to the rapid influx of sodium ions.
- Potassium channels and L-type calcium channels open after sodium channels close.
- The plateau phase, unique to cardiac muscle, is due to the balance between calcium influx and potassium efflux.
- The plateau phase allows the chamber to finish pumping blood efficiently.
- Calcium channels close, and potassium channels remain open during repolarization.
- The repolarization phase brings the cardiomyocyte back to resting membrane potential.
- Adjacent cardiomyocytes or cells of the electrical conduction system can stimulate another action potential.
"Test your knowledge on Cardiomyocyte Action Potential! Learn about the three channels involved, the depolarization and repolarization phases, and the unique plateau phase. Discover how adjacent cells stimulate another action potential and understand the importance of this process for efficient blood pumping. Challenge yourself with this quiz and master the fundamentals of cardiac electrophysiology today!"
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