C2.2 Neural Signalling (SV)

Which part of the neuron typically receives signals from other neurons?

• Dendrites
• Axon
• Nucleus
• Schwann cells

Answer explanation

Dendrites are specialized structures that receive signals. The axon sends signals, the nucleus contains genetic material, and Schwann cells are involved in myelination.

What is the role of myelin sheath in nerve impulse transmission?

• Speeds up the transmission
• Initiates the impulse
• Stops the impulse
• Converts the impulse to chemical form

Answer explanation

Myelin sheath acts as an insulator, increasing the speed of electrical impulses along the axon. It does not initiate, stop, or convert impulses.

What is the primary function of sensory neurons?

• Carry impulses from sensory receptors to the CNS
• Carry impulses from the CNS to the muscles
• Connect different neurons within the CNS
• Secrete neurotransmitters

Answer explanation

Sensory neurons are specifically designed to transmit sensory information from receptors to the CNS, not to perform the functions listed in the other options.

What occurs during hyperpolarisation in a neuron?

• The cell becomes less responsive to stimuli
• The cell becomes more responsive to stimuli
• The neuron generates an action potential
• The neuron stops all electrical activity

Answer explanation

Hyperpolarisation increases the negative charge inside the neuron making it less responsive to further stimuli, and does not cause increased responsiveness, action potential generation, or cessation of activity.

How does the nervous system distinguish between a weak and a strong stimulus?

• By the frequency of action potentials
• By the size of action potentials
• By the type of neurotransmitters released
• By the speed of action potential travel

Answer explanation

The nervous system uses the frequency of action potentials to differentiate stimulus intensity since the size of action potentials does not change.

What is the function of Schwann cells in the nervous system?

• Transmission of nerve impulses
• Form the myelin sheath
• Reception of nerve impulses
• Synthesis of neurotransmitters

Answer explanation

Schwann cells form the myelin sheath around axons in the peripheral nervous system, which insulates and speeds up impulse transmission. They do not transmit, receive impulses, or synthesize neurotransmitters.

In a synapse, what does the neurotransmitter acetylcholine interact with to propagate a nerve impulse?

• Dopamine receptors
• Adenosine receptors
• Cholinergic receptors
• GABA receptors

Answer explanation

Acetylcholine interacts with cholinergic receptors to propagate nerve impulses across the synapse. Other options list receptors for different neurotransmitters.

During an action potential, what initially causes the inside of a neuron to become positively charged?

• K+ ions entering the neuron
• Na+ ions entering the neuron
• Ca2+ ions entering the neuron
• Cl- ions entering the neuron

Answer explanation

The influx of Na+ ionsinto the neuron during the depolarization phase of an action potential causes the inside of the neuron to become positively charged. K+, Ca2+, and Cl- ions have different roles in the neuron's activity.

What is the primary role of motor neurons?

• Transmit impulses from CNS to muscles or glands
• Receive sensory information from external stimuli
• Connect sensory and motor pathways in the CNS
• Produce myelin sheath for other neurons

Answer explanation

Motor neurons transmit impulses from the CNS to muscles or glands, known as effectors, to provoke a response, unlike the other options which describe different neuron functions.

What is the primary function of relay neurons?

• Transmit impulses across long distances
• Connect sensory neurons to motor neurons within the CNS
• Receive signals from the environment
• Secrete hormones into the bloodstream

Answer explanation

Relay neurons, or interneurons, primarily connect sensory neurons to motor neurons within the CNS, facilitating communication and integration of signals.