Neurons & Glia

A set of vocabulary flashcards covering neurons, glia, cellular components, signaling, staining techniques, and research methods from the lecture notes.

Neuron

A nerve cell that sends signals to other neurons and glia; ~85 billion in the human brain; basic signaling unit of the nervous system.

Glia

Non-neuronal support cells in the nervous system with roles such as myelination, nutrient transport, waste cleanup, CSF production, and protection.

Synapse

The junction between two neurons where communication occurs via neurotransmitters.

Action potential

A rapid, all-or-none electrical impulse that travels along an axon, initiated at the axon hillock when threshold is reached.

Excitatory

Type of signal that depolarizes the postsynaptic cell, increasing the likelihood of an action potential.

Inhibitory

Type of signal that hyperpolarizes the postsynaptic cell, decreasing the likelihood of an action potential.

Axon

The long projection of a neuron that conducts electrical impulses away from the soma toward synapses.

Dendrite

Branching projections of a neuron that receive inputs from other neurons.

Soma (cell body)

The cell body of a neuron, containing the nucleus and organelles.

Nucleus

Organelle containing the neuron’s genetic material; houses DNA.

Dendritic spine

Small protrusion on a dendrite where synapses form; highly plastic.

Axon terminal

End of the axon where neurotransmitters are released into the synapse.

Axon hillock

Cone-shaped region where action potentials are initiated if threshold is met.

Myelin sheath

Insulating layer around many axons; speeds conduction, produced by oligodendrocytes in the CNS.

Node of Ranvier

Gaps in the myelin sheath with high concentrations of voltage-gated channels for saltatory conduction.

Presynaptic cell

Neuron that releases neurotransmitters into the synapse.

Postsynaptic cell

Neuron that receives neurotransmitters and responds to them.

Neurotransmitters

Chemical messengers released into the synapse to influence the postsynaptic cell.

Gray matter

Regions rich in neuronal cell bodies; contrasts with white matter.

White matter

Regions rich in myelinated axons; appears white due to myelin.

Cytoplasm

Jelly-like interior of the cell excluding the nucleus; contains organelles.

Cytoskeleton

Network of protein filaments that give structure and enable transport; includes microtubules and actin filaments.

Microtubules

Thick filaments that maintain shape and serve as tracks for transport.

Actin filaments

Thin filaments involved in cell movement and shaping the cell.

Golgi apparatus

Organelle that packages and ships proteins and lipids to their destinations.

Rough endoplasmic reticulum

ER studded with ribosomes; synthesizes and folds proteins destined for membranes or secretion.

Smooth endoplasmic reticulum

ER without ribosomes; synthesizes lipids and processes molecules.

Mitochondria

Energy-producing organelles that generate ATP for cellular processes.

Lysosome

Organelle containing enzymes that digest waste materials and debris.

Dendritic spines

Protrusions on dendrites where excitatory synapses commonly form; plastic.

Endoplasmic reticulum

Network of membranes involved in protein and lipid synthesis (includes rough and smooth types).

Membrane (plasma membrane)

Phospholipid bilayer surrounding the cell; hydrophilic heads face water, hydrophobic tails face inward.

Phospholipid bilayer

Two-layer arrangement of phospholipids forming the cell membrane.

Hydrophilic head

Polar, water-loving part of a phospholipid that interacts with water.

Hydrophobic tail

Nonpolar, water-fearing part of a phospholipid that avoids water.

Ependymal cells

Glial cells lining the ventricles; produce cerebrospinal fluid (CSF).

Astrocytes

Glia that support neurons, regulate nutrients from blood, and contribute to the blood-brain barrier.

Oligodendrocytes

Glial cells that form the myelin sheath around CNS axons.

Microglia

Glial cells that act as the cleanup crew and respond to injury or disease.

Blood-brain barrier

Selective barrier formed by endothelial cells and glial end-feet that protects the brain from harmful substances.

CSF (cerebrospinal fluid)

Fluid surrounding the brain and spinal cord; cushions and nourishes neural tissue.

Three Rs

Replace, Reduce, Refine — ethical guidelines to minimize animal use in research.

IACUC

Institutional Animal Care and Use Committee; oversees animal research ethics.

Brodmann’s areas

Brain regions defined by cellular architecture used to map function.

Golgi stain

Stains the entire neuron (soma, dendrites, axons); darkly colors the neuron.

Nissl stain

Stains neuronal cell bodies blue/purple, highlighting cytoarchitecture.

Weigert stain

Stains axons (white matter).

Electron microscopy

Microscopy using electron beams for ultrahigh resolution of cellular ultrastructure.

Patch clamp

Electrophysiology method to measure electrical currents in individual neurons.

Ex vivo

Study of biological material outside the living organism.

In vivo

Study of processes within a living organism.

In vitro

Study of processes in a controlled environment outside a living organism.

Spatial resolution

Ability to distinguish small structures in space in imaging.

Temporal resolution

Ability to distinguish events in time in imaging.

Threshold

Membrane potential at which an action potential is triggered.

All-or-none

Once threshold is reached, the action potential fires completely; otherwise it does not.

Presynaptic

Neuron that releases neurotransmitters into the synapse.

Postsynaptic

Neuron that receives neurotransmitters and responds to them.

Synaptic transmission

Process of neurotransmitter release, diffusion, and receptor binding across the synapse.

Myelination

Formation of a myelin sheath around axons by glial cells to increase conduction speed.