5.3.2 Generation and transmission of nerve impulses

• When a cell is not transmitting signals, it maintains a resting potential of approximately -70 mV.
• Sodium ion concentration is higher inside the cell than outside.

  False
• What is depolarization?

  Membrane potential becomes less negative
• An action potential involves a sudden influx of Na+ ions followed by an efflux of K+ ions.


  True
• An action potential is triggered by a threshold level of depolarization.
• Match the process with its ion movement:

  Depolarization ↔️ Na+ influx

  Repolarization ↔️ K+ efflux
• Hyperpolarization makes the membrane potential more negative than the resting potential.


  True
• Ion channels are specialized proteins that allow the selective passage of specific ions across the cell membrane.
• Sodium channels open during depolarization to allow Na+ influx


  True
• What ion is involved in neurotransmitter release at synapses?

  Calcium
• What is membrane potential defined as?

  Electrical potential difference
• How many Na+ ions does the sodium-potassium pump transport out of the cell?

  3
• Potassium ion leakage through channels contributes to the negative charge inside the cell

  True
• What is membrane potential?

  Electrical potential difference
• How many Na+ ions are transported out of the cell by the sodium-potassium pump?

  3
• Potassium ions leak out through potassium ion channels creating a negative charge inside the cell.
• What ions move during the depolarization phase of an action potential?

  Na+ influx
• Repolarization occurs when potassium ion channels open, allowing potassium (K+) ions to flow out of the cell.
• What pump restores the normal resting potential after hyperpolarization?

  Sodium-potassium pump
• What are ion channels composed of?

  Specialized proteins
• Potassium channels open during repolarization to allow K+ efflux
• The selective permeability of ion channels is crucial for maintaining electrochemical gradients

  True
• The resting potential of a neuron is approximately -70 mV
• What pump helps maintain the resting potential of a cell?

  Sodium-potassium pump
• What causes depolarization in a neuron?

  Na+ influx
• An action potential involves both Na+ influx and K+ efflux


  True
• Depolarization results in a membrane potential that becomes less negative
• Hyperpolarization makes the membrane potential more negative than the resting potential

  True
• The sodium-potassium pump restores the normal resting potential
• Hyperpolarization occurs when the membrane potential becomes more negative
• Which pump helps restore the normal resting potential after hyperpolarization?

  Sodium-Potassium Pump
• Ion channels allow the selective passage of ions such as sodium, potassium, and calcium.


  True
• The selective permeability of ion channels is crucial for maintaining electrochemical gradients
• What is the insulating structure that wraps the axon in myelinated neurons?

  Myelin Sheath
• Saltatory conduction allows action potentials to "jump" between nodes of Ranvier, increasing propagation speed.


  True
• Saltatory conduction is the mechanism of impulse propagation in unmyelinated neurons.

  False
• Why is the refractory period important for nerve impulse transmission?

  Prevents overexcitation
• An action potential is triggered by a sufficient level of depolarization
• What is the ion movement during depolarization?

  Na+ influx
• What ion movement occurs during repolarization?

  K+ efflux