An increase in the strength of the stimulus being applied

Changes in the relative refractory period with continued stimulation

A reduction in the strength of the stimulus being applied

Many factors including effects due to ion channels adapting when a constant stimulus is applied for long

Changes in the absolute refractory period with continued stimulation

interference from the electrical supply

the noise from the chatter of other students

noise picked up from the fluorescent lights

the low frequency vibration of the building

the low frequency vibration of the air conditioning

the Cl^- permeability increases rapidly

Na⁺ permeability increases rapidly

voltage-gated K⁺ channels immediately open

K⁺ permeability slowly decreases

passive Na⁺ channels are inactivated

Leakage of K⁺ out of the cell while large anions cannot follow

Leakage of Cl^- and large anions out of the cell

Leakage of K⁺ and Cl^- out of the cell

Leakage of K⁺ out of the cell balanced by leakage of Na⁺ into the cell

Leakage of K⁺ and Na⁺ out of the cell

All of the axons are myelinated  but they vary in diameter

All of the axons are unmyelinated  but they vary in length

Some of the axons are myelinated and others are not

The recording electrode is located at different distances from different neurons

All of the axons are unmyelinated  but they vary in diameter

it allows Na⁺ and K⁺ concentrations to re-equalize at points that have already produced APs.

APs can generally travel in only one direction along the neuron.

it allows electrotonic current spread from one point to the next along the neuron.

it allows neurons to respond even to a second stimulus presented 1msec after the first one.

it allows the AP threshold to recover.

The Schwann cell does not wind around them to form the sheath

They are not associated with oligodendrocytes

Only oligodendrocytes but not Schwann cells form the sheath

They are not associated with Schwann cells

The oligodendrocyte does not wind around them to form the sheath

would have been absent if measurements had been done by a trained neurologist

would have been absent if measurements had been done at a higher room temperature

cannot be altered by changing skin temperature or using more conductive gel

is absent when measurements are done in a patient with diabetic neuropathy

would have been absent if measurements had been done with more conducting gel

Varying either the size or the number of APs they produce, proportionate to the stimulus strength

Varying the shape of APs they produce, proportionate to the stimulus strength

Varying the number of APs they produce, proportionate to the stimulus strength

Increasing the size of the APs they produce, proportionate to the stimulus strength

Varying the width of APs they produce, proportionate to the stimulus strength