psychology exam 1

LO 3

Ions

An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons.

Anions

A negatively charged ion, such as a protein or a chloride ion

Cations

A positively charged ion, such as a potassium or sodium ion.

Resting potential

The difference in electrical potential across the membrane of a nerve cell at rest.

Ion channel

A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open.

Potassium ions (K+)

A potassium atom that carries a positive charge.

Sodium ions (Na+)

A sodium atom that carries a positive charge

Diffusion

the movement of molecules from high to low concentration until evenly spread out

Electrostatic pressure

The propensity of charged molecules or ions to move toward areas with the opposite charge.

Hyperpolarization

An increase in membrane potential (the interior of the neuron becomes even more negative).

Depolarization

A decrease in membrane potential (the interior of the neuron becomes less negative).

Threshold

The stimulus intensity that is just adequate to trigger an action potential in an axon.

Action potential

a rapid change in a neuron’s membrane potential that briefly makes the inside positive.

All-or-none property

The condition that the size (amplitude) of the action potential is independent of the size of the stimulus.

Voltage-gated channels (Na+)

A Na+-selective channel that opens or closes in response to changes in the voltage of the local membrane potential. It mediates the action potential.

Voltage-gated channels (K+)

membrane channels that open in response to changes in voltage, allowing potassium ions (K⁺) to move out of the neuron

Ligand-gated channels

A substance that binds to receptor molecules, such as a neurotransmitter or drug that binds to postsynaptic receptors.

Multiple sclerosis

a disease in which the immune system damages myelin, disrupting communication between the brain and body.

Postsynaptic potentials

a small local change in membrane potential caused by stimulation at a synapse.

EPSP

A depolarizing potential in a neuron that is normally caused by synaptic excitation. (Increases the probability that the postsynaptic neuron will fire an action potential)

IPSP

A hyperpolarizing potential in a neuron. (Decreases the probability that the postsynaptic neuron will fire an action potential.)

Chloride ions (Cl-)

negatively charged ions that help regulate electrical activity in cells and neurons.

Synaptic transmission

the process of sending signals between neurons through neurotransmitters at a synapse

Calcium ions (Ca2+)

A calcium atom that carries a double positive charge

Active neurotransmitter clearance

the removal of neurotransmitters by breakdown (degradation) or reabsorption (reuptake).

Degradation

The breakdown of neurotransmitters by enzymes

Reuptake

The reabsorption of neurotransmitters back into the presynaptic neuron