Neurophysiology and Action Potentials Vocabulary Flashcards

Vocabulary flashcards covering resting potentials, action potentials, refractory periods, neural structures, and membrane dynamics based on lecture notes.

Resting Potential

The resting state of a neuron where the inside is negatively charged relative to the outside, maintaining a voltage around $-70\,mV$ (ranging between $-40\,mV$ and $-80\,mV$).

Action Potential

A rapid depolarization of the inside of the cell relative to the outside to $0\,mV$ or a positive charge ($+30\,mV$ to $+40\,mV$), triggered when excitatory stimulation reaches threshold.

Local Potential

A graded and decremental signal originating in dendrites that partially depolarizes the membrane with a small amount of polarization and does not pass along the axon.

All-or-None Law

The principle stating that an action potential either fires completely or does not fire at all, maintaining the exact same intensity down the axon.

Depolarization

The phase of an action potential where sodium channels open, allowing $\text{Na}^+$ ions to enter the cell and causing the cell's potential to overshoot to positive (~$30-40\,mV$).

Repolarization

The resetting phase where sodium channels close and potassium channels open, allowing $\text{K}^+$ ions to leave the cell to restore a negative charge.

Hyperpolarization

A state where the membrane voltage becomes more negative than at rest, requiring a greater excitatory stimulation to reach threshold and fire again.

Absolute Refractory Period

The period during depolarization and repolarization when a neuron cannot fire another action potential under any circumstances.

Relative Refractory Period

The period during hyperpolarization where the cell requires a greater than normal excitatory stimulation to fire an action potential.

Interneuron

A multipolar neuron responsible for spinal reflexes and higher-order brain processes that communicates locally and may or may not have an axon.

Afferent

A term describing the direction of a neural message traveling from the outside to the inside.

Efferent

A term describing the direction of a neural message traveling from the inside to the outside.

Voltage

A measure of the amount of electrical energy difference between the inside and the outside of a neuron.

Polarization

The state representing the existence of an electrical energy difference between the inside and outside of a cell.

Diffusion

The movement of ions from an area of high concentration to an area of low concentration.

Electrostatic Pressure

The electrical force causing two like-charged ions to repel each other and oppositely charged ions to attract each other.

Neural Membrane

A semi-permeable structure made of lipid molecules with heads oriented toward extracellular and intracellular fluids, containing protein channels to maintain voltage.

Anions ($\text{A}^-$)

Negatively charged ions inside the cell that cannot pass through the cell membrane.

Sodium-Potassium Pumps

Membrane mechanisms that maintain the state of polarization by exchanging $2$ potassium ions into the cell for every $3$ sodium ions pumped out.

Ion Channels

Pores in the cell membrane that control the flow of ions into and out of the cell, which are chemically or electrically gated and open when threshold is met.

Ligand

Chemicals that can bind to and open gated ion channels.