IB Biology: A1.2-Oscilloscope Traces

Front

What is an oscilloscope?

Back

A device that registers electrical voltages and displays them on a screen as time passes.

Front

How are membrane potentials of neurons measured?

Back

By placing electrodes on each side of the membrane.

Front

What does an oscilloscope trace of a neuron show?

Back

A graph of the membrane potential values (in mV) as it would appear on the screen of an oscilloscope.

Front

What does a horizontal line at -70mV on an oscilloscope screen indicate?

Back

It indicates the resting potential of a neuron.

Front

What happens during the repolarization phase?

Back

The membrane potential does not usually return to -70mV immediately and changes gradually until the resting potential is reached.

Front

What is the resting state of a neuron?

Back

Neuron at its resting membrane potential of −70 mV.

Front

What is the threshold in neuron membrane potential?

Back

The membrane potential reaches a critical threshold, triggering an action potential.

Front

What occurs during depolarization?

Back

A stimulus causes a brief influx of sodium ions, leading to depolarization of the cell membrane.

Front

What happens during the rising phase?

Back

Voltage-gated sodium channels open, allowing a rapid influx of sodium ions, further depolarizing the cell.

Front

How is the resting potential restored?

Back

Na and K ions return to their resting distribution through the action of the Na+/K+ pump, restoring the cell to its resting membrane potential.