Bases of Information Processing

Vocabulary flashcards covering the biological bases of information processing including resting potential, action potential mechanics, and neural communication.

Resting potential

A dynamic and balanced flow of ions between the outside and inside of a neuron in the absence of a nerve impulse, where the axon electrical potential is around $-70\,mV$.

Diffusion

The passive movement of small ions from an area of high concentration to an area of low concentration across the membrane through ion channels.

Voltage-gated channels

Ion channels that open or close depending on the membrane potential or voltage.

Ligand-gated channels

Ion channels that open when a chemical messenger or neurotransmitter binds to the channel.

Ion pumps

Active transport transmembrane proteins that use energy from $ATP$ to move ions against their gradient by changing their conformation.

$Na^+/K^+$ pump

A transmembrane protein that uses $1$ molecule of $ATP$ to push out $3\,Na^+$ ions and bring in $2\,K^+$ ions per cycle, maintaining ion concentrations.

Action potential

An electrical discharge wave that travels along the cell membrane, modifying its electrical charge distribution.

Excitation threshold

The voltage level of approximately $-55\,mV$ that must be reached to open voltage-gated $Na^+$ channels and trigger an action potential.

Depolarization

The reversal of the resting potential to approximately $+40\,mV$ caused by the sudden entry of $Na^+$ into the neuron.

Postsynaptic potential (PSP)

The electrical response of a neuron receiving a signal from another neuron; it is bidirectional and becomes less powerful as it moves toward the axon hillock.

Excitatory synapse (EPSP)

A synapse where neurotransmitters open channels that let positive ions like $Na^+$ enter, making the neuron less negative and closer to the threshold.

Glutamate

A common excitatory neurotransmitter mentioned in the text.

Inhibitory synapse (IPSP)

A synapse where neurotransmitters open channels that let negative ions ($Cl^-$) enter or positive ions ($K^+$) leave, resulting in hyperpolarization.

GABA

A common inhibitory neurotransmitter mentioned in the text.

Repolarization

The phase where the interior of the cell loses positive charges and becomes negative again due to the accumulation of $K^+$ outside the membrane.

Absolute refractory period

The time immediately after an action potential lasting $1$ or $2\,ms$ during which no stimulus can trigger another action potential.

Relative refractory period

The period following the absolute refractory period, lasting $3$ or $4\,ms$, when a neuron can fire again but requires a stronger-than-normal stimulus.

Nodes of Ranvier

Sections of myelinated fibers that are not insulated by myelin and contact the extracellular fluid; they are the only sites where action potentials occur on these fibers.

Withdrawal reflex (flexor reflex)

A fast, involuntary, and protective spinal reflex response that pulls a body part away from a potentially harmful stimulus.

Sensory neuron (afferent neuron)

A neuron that detects painful stimuli via dendrites and transmits an action potential along its axon toward the spinal cord.

Interneuron (association neuron)

The middle connector inside the spinal cord that receives neurotransmitters from sensory neurons and transmits signals to motor neurons.

Motor neuron (efferent neuron)

A neuron that sends an action potential toward a muscle, forming a synapse at the neuromuscular junction to trigger contraction.