BIO 135 Activity - Neuron Signaling

These flashcards cover the vocabulary and key concepts related to neuron signaling focusing on membrane potential changes and action potentials.

Leakage ion channel

Membrane protein that is always open, letting solutes in/out of cell.

Voltage gated ion channel

Membrane protein that opens or closes in response to changes in membrane potential.

Action potential (AP)

Electrical impulse (voltage wave) that travels down axons; doesn't weaken.

Resting membrane potential

Normal voltage across the cell membrane.

Graded potential

Short-lived, localized changes in membrane potential; weakens with distance and varies in strength.

Depolarization

Membrane potential (voltage) becomes less negative.

Hyperpolarization

The voltage gets more negative than the resting potential of -70 mV.

Sodium-potassium pump

Membrane transport protein that restores Na+ and K+ concentrations to their resting state after an action potential.

Sodium ion (Na+)

Rushes into cell at start of AP during depolarization; highly concentrated outside of the cell when cell is at rest.

Potassium ion (K+)

Rushes out of cell during repolarization step of an AP; concentrated in the axon when the neuron is at rest.

Resting state

Na+ and K+ channels are closed; axon has resting membrane potential.

Depolarization step

Na+ channels open, Na+ rushes into axon; voltage becomes less negative.

Repolarization step

Some K+ channels are open; Na+ channels reset; voltage becomes slightly less negative.

Hyperpolarization step

K+ channels are open; Na+ channels are inactivating; voltage becoming more negative.

All-or-none concept

An action potential either happens completely or not at all.

Propagation

Wave-like movement of the action potential along the axon due to positive feedback of local depolarization.

Continuous conduction

Action potential that occurs in nonmyelinated axons; is relatively slow.

Saltatory conduction

Action potential propagated at gaps in myelinated sheath; is relatively fast.

Absolute refractory period

No chance of an action potential firing; Na+ channels are open or haven't reset.

Relative refractory period

An action potential will only fire if there is an especially strong stimulus.