IB Biology: C2.2-Nerve Impulses as Action Potentials

What is depolarisation?

• A gradual increase in membrane potential from -70 mV to +30 mV.

• A sudden change in membrane potential from -70 mV to +30 mV, also called an action potential.

• The process of returning the membrane potential to its resting state after an action potential.

• A decrease in membrane potential, making the inside of the cell more negative.

How is an action potential generated?

• An action potential is generated when the resting membrane potential of a neuron rises from -70 mV to +30 mV.

• An action potential occurs when a neuron is at rest and does not transmit signals.

• An action potential is generated when the membrane potential drops below -70 mV.

• An action potential is created by the influx of calcium ions into the neuron.

Why are nerve impulses considered electrical?

• They involve the movement of negatively charged ions.

• They involve the movement of positively charged ions.

• They are caused by chemical reactions in the brain.

• They are generated by muscle contractions.

What is repolarisation?

• The process of increasing the membrane potential to +30 mV.

• The restoration of a membrane potential following depolarisation, restoring it back to -70 mV from +30 mV.

• The initial phase of action potential where the membrane potential becomes more positive.

• The process of maintaining a stable membrane potential at +30 mV.

What is an action potential?

• A gradual increase in membrane potential leading to depolarization.

• The sudden, rapid reversal of the potential difference across the axonal membrane from -70mV to +30mV.

• A type of neurotransmitter released at synapses.

• A slow change in the resting membrane potential.

What is the role of action potentials in nerve fibres?

• They are responsible for muscle contraction.

• They are action potentials that are propagated along nerve fibres.

• They transmit blood flow in the circulatory system.

• They are involved in the digestion process.

How is a stimulus processed in the nervous system?

• A stimulus is picked up by a sensory receptor and transferred to the dendrites of a sensory neuron. The impulses then travel from the dendrites to the cell body, and from the cell body to the axon and the terminals.

• A stimulus is directly transmitted to the brain without any sensory receptors involved.

• A stimulus is ignored by the sensory receptors and does not affect the nervous system.

• A stimulus is processed only in the spinal cord and does not involve the brain.