C2.2 Neural signalling SL/HL

What is the primary function of neurons in the nervous system?

• Transmit information
• Produce hormones
• Store memories
• Filter blood

Answer explanation

Neurons are specialized to transmit information in the form of impulses, facilitating communication within the nervous system. Other options, while important biological functions, are not the roles of neurons.

Which ions are primarily involved in generating the resting potential in neurons?

• Sodium
• Potassium
• Calcium
• Iron

Answer explanation

Sodium and potassium ions are crucial for establishing the resting potential in neurons by creating concentration gradients across the cell membrane. Calcium and iron are not primarily involved in this process.

In the context of nerve impulses, what does an action potential represent?

• A momentary reversal
• A constant state
• A decrease
• An increase

Answer explanation

An action potential is described as a momentary reversal in the electrical potential difference across a neuron's membrane, crucial for transmitting impulses.

Fill in the blank: Synapses are junctions between neurons and between neurons and _______.

Answer explanation

Synapses function as junctions where neurons can communicate with other neurons or with effector cells, like muscles or glands, thereby transmitting impulses necessary for response.

What type of neuron carries impulses from the central nervous system to the muscles or glands?

• Motor neuron
• Sensory neuron
• Relay neuron
• Schwann cell

Answer explanation

Motor neurons are responsible for transmitting impulses from the CNS to muscles or glands (effectors), facilitating responses to stimuli.

What is the primary role of the myelin sheath in the nervous system?

• Insulation
• Energy storage
• Signal creation
• Hormone production

Answer explanation

The myelin sheath provides insulation for axons, increasing the speed at which impulses propagate along the nerve fiber.

What gaps in the myelin sheath are called?

• Nodes of Ranvier
• Nodes of Schwann
• Ranvier gaps
• Myelin nodes

Answer explanation

The gaps in the myelin sheath, which allow ions to flow in and out of the neuron, accelerating impulse transmission, are called Nodes of Ranvier.

Which cells form the myelin sheath in the peripheral nervous system?

• Schwann cells
• Glial cells
• Neurons
• Red blood cells

Answer explanation

Schwann cells wrap around axons in the peripheral nervous system to form the myelin sheath, essential for proper nerve function.

What is saltatory conduction?

• Jumping of impulses
• Smooth flow
• Linear transfer
• Random movement

Answer explanation

Saltatory conduction refers to the 'jumping' of action potentials along myelinated axons from one Node of Ranvier to another, which speeds up neural transmission.

How do inhibitory neurotransmitters affect postsynaptic neurons?

• Reduce potential
• Increase potential
• Stabilize only
• No effect

Answer explanation

Inhibitory neurotransmitters generally decrease the likelihood of the postsynaptic neuron firing an action potential, thus reducing its activity.