topic 6 pt 6-7

What is the role of myelination in axons?

• Acts as an effective electrical insulator

• Increases the number of voltage-gated Na⁺ channels

• Decreases the speed of action potential

• Prevents depolarization

What is the function of nodes of Ranvier in myelinated axons?

• Contain voltage-gated Na⁺ channels

• Prevent depolarization

• Act as electrical insulators

• Decrease the speed of action potential

The result of myelination in terms of electrical current is that current _____ from node to node.

• jumps

• flows continuously

• is blocked

• is slowed down

The conduction of an action potential is _____ in a myelinated axon compared to an unmyelinated axon.

• Much faster in a myelinated axon

• Much slower in a myelinated axon

• The same speed in both

• Stops at nodes in a myelinated axon

In an unmyelinated axon, channels must be located _____.

• Closer together

• Farther apart

• Randomly distributed

• Only at the axon hillock

What happens at the synaptic knob when an action potential arrives?

• Voltage-gated Ca²⁺ channels open

• Voltage-gated Na⁺ channels open

• Neurotransmitter is degraded

• Synaptic vesicles are destroyed

_____ binds to synaptic vesicles loaded with neurotransmitter.

• Ca²⁺

• Na⁺

• K⁺

• Cl⁻

What triggers a post-synaptic potential?

• Neurotransmitter binding to ligand-gated channels

• Voltage-gated Na⁺ channels opening

• Action potential reaching the axon hillock

• Depolarization of the axon

The postsynaptic cell _____ when Na⁺ channels are affected.

• Depolarizes

• Hyperpolarizes

• Remains unchanged

• Releases neurotransmitter

The effect of K⁺ channels on the postsynaptic cell is _____

• Hyperpolarization

• Depolarization

• No effect

• Increased neurotransmitter release