6.2.2 Nerve Impulse Transmission

• Match the part of a neuron with its description:

  Cell body ↔️ Contains the nucleus

  Dendrites ↔️ Receives signals

  Axon ↔️ Transmits signals

  Myelin sheath ↔️ Speeds up signal transmission
• Arrange the following steps in the process of depolarisation:

  1️⃣ Sodium channels open

  2️⃣ Influx of Na+ ions

  3️⃣ Membrane potential becomes less negative
• The sodium-potassium pump requires ATP to maintain the electrochemical gradient during the resting potential.


  True
• Depolarisation is the process where the membrane potential becomes less negative
• During depolarisation, the sodium ion concentration increases inside
• Continuous conduction occurs in myelinated axons.

  False
• Thicker and myelinated axons conduct nerve impulses faster.


  True
• During repolarisation, potassium ions flow out
• The resting potential of a neuron is typically around -70 mV
• During depolarisation, the membrane voltage becomes less negative
• Sodium ion concentration is higher outside the cell during the resting potential.


  True
• The membrane voltage becomes less negative during depolarisation.


  True
• In saltatory conduction, depolarisation occurs only at the nodes
• Which channels close during repolarisation to prevent further Na+ influx?

  Sodium channels
• What are the three main structures of a synapse?

  Presynaptic neuron, synaptic cleft, postsynaptic neuron
• After transmission, neurotransmitters are removed from the synaptic cleft through enzymatic degradation or reuptake
• Neurotransmitters bind to receptors on the postsynaptic neuron to transmit nerve impulses.
• The resting potential of a neuron is typically around -70 mV.
• Depolarisation is a key step in the propagation of a nerve impulse.
• Which ion is responsible for the influx that causes depolarisation?

  Sodium
• In the resting potential, the membrane voltage is -70 mV.


  True
• Depolarisation is a key step in the propagation of a nerve impulse.


  True
• In saltatory conduction, depolarisation "jumps" between the nodes of Ranvier
• Repolarisation is the process where the membrane potential returns to its resting value of -70 mV
• Depolarisation involves Na+ influx, while repolarisation involves K+ efflux.


  True
• The sodium-potassium pump maintains the resting potential by transporting Na+ out and K+ in.

  True
• Establishing an electrochemical gradient ensures the membrane voltage remains negative
• Where is potassium ion concentration higher during the resting potential?

  Inside the cell
• What is the role of depolarisation in nerve impulse propagation?

  Triggers adjacent depolarisation
• What two factors influence the speed of action potential propagation?

  Axon diameter and myelination
• During repolarisation, potassium channels open, causing efflux
• Neurotransmitters can cause either excitatory or inhibitory postsynaptic potentials.


  True
• What is the primary role of glutamate as a neurotransmitter?

  Excitatory, learning and memory
• What is the basic structural and functional unit of the nervous system?

  Neuron
• The sodium-potassium pump maintains the resting potential by moving Na+ out of the cell and K+ into the cell.

  True
• What is the function of the myelin sheath?

  Speeds up signal transmission
• During depolarisation, the concentration of sodium ions increases inside the neuron.
• Depolarisation occurs when sodium channels open, allowing an influx of sodium ions
• Match the type of conduction with its characteristics:

  Continuous conduction ↔️ Step-by-step depolarisation along the entire axon

  Saltatory conduction ↔️ Depolarisation jumps between nodes of Ranvier
• Order the following steps of action potential propagation in a myelinated axon:

  1️⃣ Depolarisation begins at a node of Ranvier

  2️⃣ Local current spreads to the next node

  3️⃣ Sodium channels open at the next node

  4️⃣ Depolarisation "jumps" to the next node