Neurons

Sensory input

The ability to perceive the environment through receptors.

Integration Center

The part of the nervous system where sensory information is received, interpreted, and a response is formulated.

Motor Output

The process through which motor neurons send output away from the nervous system to effector organs such as muscles or glands.

Myelin

A lipid-rich insulation structure around an axon that increases the speed of nerve signal transmission.

Cell body

The region of a neuron where most organelles and neurotransmitter synthesis occur.

Dendrites

Branched structures of a neuron that increase surface area for receiving incoming signals.

Axon

The conducting region of a neuron where signals travel.

Axon terminals

The secretory region of a neuron that releases neurotransmitters.

Excitatory neurotransmitter

Type of neurotransmitter that increases the likelihood of an action potential, e.g., acetylcholine.

Inhibitory neurotransmitter

Type of neurotransmitter that reduces the likelihood of an action potential.

Resting membrane potential

The electrical charge difference across the neuronal membrane when the neuron is at rest.

Voltage

The stored energy resulting from the separation of charges across a membrane.

Current

The flow of ions that generates an electric signal.

Potassium Leak Channels

Channels that allow potassium ions to flow out of the cell, contributing to the resting membrane potential.

Sodium-Potassium Pump

A membrane protein that actively transports sodium out and potassium into the cell, essential for establishing resting potential.

Gated channels

Membrane channels that require a specific stimulus to open.

Ligand-gated channel

A type of gated channel that opens when a ligand binds to it.

Voltage-gated channel

A channel that opens in response to a change in membrane potential.

Action Potential (AP)

A long-distance electrical signal with an all-or-nothing characteristic.

Graded Potentials (GP)

Localized changes in membrane potential that vary in strength and can decay over distance.

Trigger zone

The region of the axon where graded potentials are integrated to initiate an action potential.

All-or-nothing principle

The concept that action potentials either occur fully or not at all.

Depolarization

The process during an action potential when sodium ions enter the cell, making it more positive.

Repolarization

The phase following depolarization when potassium ions exit the cell, restoring the negative resting potential.

Hyperpolarization

An increase in the negative charge inside the neuron, making it less likely to fire an action potential.

Threshold

The critical level of depolarization needed to trigger an action potential.

Neurotransmitter

Chemical messengers released from axon terminals that transmit signals across synapses.

Postsynaptic cell

The cell that receives signals from a presynaptic neuron.

Synapse

The junction between two neurons where neurotransmission occurs.

Resting state of a neuron

Condition of a neuron when it is not actively transmitting a signal.

Membrane potential

The difference in electric charge across a neuronal membrane.

Ionic concentrations at rest

Higher concentration of sodium outside the neuron and higher concentration of potassium inside.

Action potential graph

Illustrates the changes in membrane potential during depolarization and repolarization.

Phospholipid bilayer

The structure that forms the cell membrane, with hydrophobic and hydrophilic regions.

Intracellular fluid

The fluid inside the cell, rich in potassium ions at rest.

Extracellular fluid

The fluid outside the cell, rich in sodium ions at rest.

Summation of Signals

The process by which multiple graded potentials combine to influence the likelihood of triggering an action potential.

Neurotransmitter receptors

Proteins on the postsynaptic cell that bind neurotransmitters and initiate a response.

Calcium channels

Channels that allow calcium ions to enter the cell, often involved in neurotransmitter release.

Refractory period

The time during which a neuron cannot fire another action potential after one has occurred.

Efferent neurons

Nerve cells that carry signals away from the central nervous system to effectors.

Afferent neurons

Nerve cells that carry sensory information towards the central nervous system.

Neuronal excitability

The ability of a neuron to respond to stimuli and transmit electrical signals.

Electrochemical gradient

The combined difference in charge and concentration of ions across the cell membrane.

Action Potential propagation

The process by which an action potential travels along an axon.

Neuronal signaling

The mechanism by which neurons communicate with each other through electrical impulses and neurotransmitters.

Membrane depolarization

A decrease in the membrane potential, making the inside of the cell more positive.

Concentration gradient

The difference in the concentration of ions across the membrane.

Resting nerve impulse

The state of a neuron where it is ready to transmit a signal but is currently inactive.

Neural circuits

Networks of interconnected neurons that process specific types of information.

Ion channels

Proteins in the cell membrane that create pathways for ions to enter or leave the cell.

Neurotransmitter release

The process by which neurotransmitters are expelled from the axon terminals into the synaptic cleft.

Calcium's role in neurotransmitter release

Calcium ions trigger the fusion of neurotransmitter vesicles with the presynaptic membrane.

Excitatory Postsynaptic Potential (EPSP)

A postsynaptic potential that makes the neuron more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A postsynaptic potential that makes the neuron less likely to fire an action potential.