C2.2 Neural Signalling Practice Quiz

Which components form the Central Nervous System (CNS)?

• The brain and all nerves in the body

• The spinal cord and all nerves in the body

• The brain and the spinal cord

• All nerves spreading out from sense organs

What is the primary function of dendrites in a neurone?

• To insulate the axon and prevent loss of nerve impulses

• To carry impulses away from the cell body

• To contain the nucleus and other cellular structures

• To connect to many other neurones and receive impulses from them

A neurone found entirely within the CNS that connects sensory and motor neurones is called a:

• Sensory neurone

• Relay neurone

• Motor neurone

• Effector neurone

What is the approximate electrical potential difference across the membrane of a neurone at rest, known as the resting potential?

• +70 millivolts (mV)

• 0 millivolts (mV)

• -70 millivolts (mV)

• +40 millivolts (mV)

Which process primarily contributes to the unequal distribution of ions that helps establish the resting potential in a neurone?

• Facilitated diffusion of sodium ions out of the axon

• Active transport of 3 sodium ions out for every 2 potassium ions into the axon

• Active transport of 2 sodium ions out for every 3 potassium ions into the axon

• Passive diffusion of potassium ions into the axon

Regarding the diffusion of ions across the neurone membrane, which statement is correct in establishing resting potential?

• The membrane is more permeable to sodium ions than potassium ions.

• Potassium ions diffuse into the cell at a faster rate than sodium ions diffuse out.

• The neurone membrane is much less permeable to sodium ions than potassium ions, so potassium ions diffuse out faster than sodium ions diffuse in.

• Negatively charged proteins inside the axon actively transport positive ions out.

During an action potential, the electrical potential difference across the membrane reverses from the resting potential to approximately what value?

• -70 mV

• +40 mV

• 0 mV

• -40 mV

How does myelination affect the speed of nerve impulse transmission?

• It slows down transmission by increasing electrical resistance.

• It allows for saltatory conduction, greatly speeding up the rate of transmission.

• It prevents impulses from jumping between nodes of Ranvier.

• It only impacts unmyelinated fibres, not myelinated ones.

What are the small, uninsulated sections in the myelin sheath where electrical impulses effectively jump from one to the next?

• Schwann cells

• Synaptic clefts

• Axon terminals

• Nodes of Ranvier

Compared to a narrow axon, how does a wider axon typically affect the speed of electrical impulse conduction?

• It slows down conduction due to increased surface area.

• It increases conduction speed because it offers less resistance to the action potential.

• It has no significant effect on conduction speed.

• It is only faster if the axon is unmyelinated.