Neuron Action Potentials and Signal Conduction

Vocabulary flashcards covering key terms related to neuronal resting potential, graded potentials, action potentials, and conduction dynamics.

Resting Potential

The stable membrane potential across a neuron in the absence of input, which is often around $-60\,\text{mV}$.

Graded Potentials

Changes to the resting potential caused by excitatory or inhibitory inputs that decay with both time and distance.

Depolarization

Also called an excitatory potential; a change in membrane potential that moves closer to the threshold potential.

Hyperpolarization

Also called an inhibitory potential; a change in membrane potential that moves farther away from the threshold potential.

Threshold Potential

The membrane potential value, often around $-50\,\text{mV}$, that must be reached at the trigger zone to initiate an action potential.

Trigger Zone

The initial segment of the axon where summation of graded potentials occurs to trigger an action potential.

Temporal and Spatial Summation

The process by which multiple excitatory depolarizations combine across time and space to push the membrane potential at the trigger zone over threshold.

Action Potential

A conducted electrical signal along an axon that maintains uniform size and duration to transmit information over distances up to $1\,\text{meter}$ or more.

Rising Phase

The phase of an action potential featuring a steep rise to a positive membrane potential (around $+40\,\text{mV}$), reversing normal polarity so the inside becomes more positive than the outside.

Falling Phase

The rapid drop in membrane potential during an action potential after a short plateau, passing the resting potential down to around $-70\,\text{mV}$ before settling back to resting potential.

All-or-None Property

The property of an action potential where its size and duration are constant for a particular neuron regardless of how far over threshold the input potential is.

Myelin Sheath

A covering surrounding an axon that increases the speed at which action potentials are conducted.

Nodes of Ranvier

The gaps between myelinated segments on an axon where the action potential conducts more slowly compared to within the myelinated segments.

Saltatory Conduction

The phenomenon where an action potential travels faster through myelinated segments and slower through the nodes of Ranvier, appearing to jump from node to node.