w1 cogneuro neurons and signalling

A set of vocabulary flashcards covering essential terms and definitions from the lecture on neurons and neural signalling.

Neuron Doctrine

Scientific theory stating that individual neurons are the fundamental, discrete units of the nervous system.

Santiago Ramón y Cajal

Spanish pathologist who first articulated the neuron doctrine; often called the father of neuroscience.

Neuron

Electrically excitable cell that senses environmental changes, transmits information, and commands bodily responses.

Glial Cell

Non-neuronal support cell that insulates, nourishes, and protects neighboring neurons.

Nucleus (Neuron)

Membrane-bound structure in the soma that houses DNA, directs protein synthesis, and regulates cell function.

Soma (Cell Body)

Central part of a neuron containing the nucleus; integrates inputs and sets membrane potential.

Cell Membrane

Lipid layer surrounding the neuron, maintaining separation of intra- and extracellular ions and charge.

Lipid Bilayer

Double layer of hydrophobic phospholipids that blocks water-soluble molecules from crossing the membrane.

Dendrite

Branched neuronal extension that receives synaptic inputs from other neurons.

Dendritic Spine

Small protrusion on a dendrite that increases surface area and acts as a micro-receiving station for synapses.

Axon

Long fiber that conducts action potentials away from the soma toward other cells.

Myelin Sheath

Fatty insulating layer around many axons that greatly speeds impulse conduction.

Nodes of Ranvier

Gaps between myelin segments where voltage-gated channels cluster and action potentials regenerate.

Saltatory Conduction

Fast signal transmission in which action potentials "jump" from node to node along a myelinated axon.

Axon Hillock

Junction between soma and axon where summed inputs are converted into an action potential.

Axon Terminal

Endpoint of an axon where neurotransmitters are released into the synaptic cleft.

Ion

Atom or molecule that carries an electrical charge.

Sodium Ion (Na⁺)

Positively charged ion abundant outside resting neurons; influx drives depolarization.

Potassium Ion (K⁺)

Positively charged ion abundant inside resting neurons; efflux drives repolarization.

Calcium Ion (Ca²⁺)

Doubly positive ion whose influx at axon terminals triggers neurotransmitter release.

Chloride Ion (Cl⁻)

Negatively charged ion found mainly outside resting neurons; contributes to membrane potential.

Resting Membrane Potential

Baseline voltage difference of ~-70 mV between inside and outside of a neuron at rest.

Ion Channel

Transmembrane protein pore allowing passive ionic flow down electrochemical gradients.

Ion Pump

ATP-driven membrane protein that actively transports ions to maintain concentration gradients.

Electrical (Voltage) Gradient

Difference in electric charge across a membrane that influences ion movement.

Electrochemical Equilibrium

Point at which chemical and electrical forces on an ion balance, halting net movement.

Decremental Conduction

Passive spread of current that diminishes with distance from its origin.

Action Potential

Brief all-or-none electrical spike produced by rapid sequential opening of voltage-gated Na⁺ and K⁺ channels.

Depolarization

Upward shift in membrane potential (toward positive) due to Na⁺ influx.

Threshold (-55 mV)

Membrane voltage at the axon hillock that opens voltage-gated Na⁺ channels, initiating an action potential.

Repolarization

Return of membrane potential toward resting level as K⁺ ions exit the neuron.

Hyperpolarization

Membrane potential becomes more negative than resting after repolarization.

Refractory Period

Time after an action potential when a neuron is incapable of or resistant to firing again.

Excitatory Postsynaptic Potential (EPSP)

Depolarizing graded potential in the postsynaptic neuron that increases the chance of firing.

Graded Potential

Small, variable change in membrane voltage that decays with distance; basis for EPSPs and IPSPs.

Exocytosis

Process by which vesicles fuse with the presynaptic membrane to release neurotransmitters.

Neurotransmitter Reuptake

Active transport of released neurotransmitter back into the presynaptic terminal for recycling.

Enzymatic Breakdown

Chemical degradation of neurotransmitters in the synaptic cleft by specific enzymes.

Electrical Synapse

Synapse that passes current directly between neurons via gap-junction channels.

Chemical Synapse

Junction where communication occurs through neurotransmitter release and receptor binding.

Astrocyte

Star-shaped glial cell that forms the blood–brain barrier and provides metabolic support.

Blood–Brain Barrier

Selective barrier that blocks pathogens and toxins in the blood from entering brain tissue.

Oligodendrocyte

Glial cell that forms myelin sheaths around axons in the central nervous system (CNS).

Schwann Cell

Glial cell that forms myelin sheaths around axons in the peripheral nervous system (PNS).

Microglial Cell

Immune-like glial cell that removes debris and damaged cells in the nervous system.

Neuroglia

Collective term for glial cells; literally means "nerve glue."

Arborization

Branching pattern of a neuron's dendrites or axon.

Eukaryotic Cell

Complex cell containing a nucleus and membrane-bound organelles.

Cytoplasm

Jelly-like intracellular fluid that surrounds organelles within a cell.

Voltage-Gated Ion Channel

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