Neurophysiology Lecture Quiz: Excitability and Ion Channels

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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 Signup and view all the answers

What is the significance of Na+ channels in the initiation of an action potential?

Na+ channels need to open to initiate an action potential Signup and view all the answers

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 Signup and view all the answers

What is the basis of nerve conduction?

Ions flowing through ion channels in excitable membranes Signup and view all the answers

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. Signup and view all the answers

What role do ion channels play in excitability?

Ion channels allow current flow across the membrane, increasing flow when open. Signup and view all the answers

Outline what makes a membrane excitable.

The presence of ion channels and ionic gradients make a membrane excitable. Signup and view all the answers

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. Signup and view all the answers

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. Signup and view all the answers

What is the resting membrane potential primarily determined by?

Permeability to K+ Signup and view all the answers

During which phase of the myocyte action potential does activation of voltage-gated Na+ channels occur?

Phase 0 Signup and view all the answers

What is the 'plateau' phase of the myocyte action potential characterized by?

Inward current through slowly activating and inactivating voltage-gated Ca++ channels. Signup and view all the answers

What is the primary cause of early repolarization during the myocyte action potential?

Inactivation of Na+ channels Signup and view all the answers

How is repolarization phase achieved in the myocyte action potential?

Inactivation of Ca++ channels and increase in permeability to K+ Signup and view all the answers

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. Signup and view all the answers