18 Questions
What determines if a channel is open or not?
Channel activation or gating mechanisms
Describe the different states of a sodium channel during an action potential.
Resting/deactivated, Activated, Inactivated
What ion movement underlies the membrane depolarization during an action potential?
Entry of Na+ ions
What process leads to the repolarization of the cell membrane after depolarization?
Opening of K+ channels
What is the significance of Na+ channels in the initiation of an action potential?
Na+ channels need to open to initiate an action potential
Explain the concept of equilibrium potential in relation to Na+ ions during an action potential.
Na+ ions move towards equilibrium, changing the balance of charges across the membrane
What is the basis of nerve conduction?
Ions flowing through ion channels in excitable membranes
Explain the ionic basis of action potential with reference to the ECG.
Changes in Na+, K+, and Ca++ concentrations lead to depolarization and repolarization seen in the ECG.
What role do ion channels play in excitability?
Ion channels allow current flow across the membrane, increasing flow when open.
Outline what makes a membrane excitable.
The presence of ion channels and ionic gradients make a membrane excitable.
Explain the basis of the membrane potential.
The membrane potential is the result of electrical and chemical gradients across the cell membrane, allowing for the movement of ions.
How do ion channels contribute to membrane excitability?
Ion channels can activate, deactivate, and modulate, allowing for the controlled flow of ions and changes in membrane potential.
What is the resting membrane potential primarily determined by?
Permeability to K+
During which phase of the myocyte action potential does activation of voltage-gated Na+ channels occur?
Phase 0
What is the 'plateau' phase of the myocyte action potential characterized by?
Inward current through slowly activating and inactivating voltage-gated Ca++ channels.
What is the primary cause of early repolarization during the myocyte action potential?
Inactivation of Na+ channels
How is repolarization phase achieved in the myocyte action potential?
Inactivation of Ca++ channels and increase in permeability to K+
Why might injection of a bolus of KCl lead to heart failure?
Due to the disruption of the ionic balance and potential effects on action potentials in the heart.
Test your knowledge on the basics of membrane excitability, membrane potential, ion channels, action potential, and nerve conduction. Learn about the fundamentals of neurophysiology with this quiz.
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