NEU 101: Neurons & Glia

Practice flashcards covering neuron and glia biology, synapses, signaling, staining methods, and research methods.

What is the approximate number of neurons in the human nervous system?

About 85 billion.

What are the two broad classes of signaling in the nervous system?

Electrical signals within a neuron and chemical signals between neurons.

Name the major structural components of a neuron involved in signaling.

Dendrites, soma (cell body), axon, axon hillock, axon terminals, synapses, and myelin sheath.

What is the function of dendrites?

They receive incoming signals from other neurons.

What is the function of the axon?

Transmits electrical impulses away from the soma toward the axon terminals.

What is the axon hillock?

The region where the action potential is initiated if the membrane potential reaches threshold.

What are dendritic spines?

Small protrusions on dendrites that host synapses and receive inputs.

What is the myelin sheath and which cells create it in the CNS?

An insulating layer around the axon that speeds conduction; created by oligodendrocytes.

What are nodes of Ranvier?

Gaps in the myelin sheath with high concentrations of ion channels that enable saltatory conduction.

What is a synapse?

The gap between a sending (presynaptic) and receiving (postsynaptic) neuron where neurotransmitters are released.

What does threshold refer to in action potentials?

The membrane potential value that must be reached at the axon hillock to trigger an action potential.

What happens if threshold is not met?

No action potential is generated.

What happens if threshold is met?

An action potential travels down the axon and the neuron fires.

What is released into the synapse when an action potential reaches the axon terminals?

Neurotransmitters.

What are excitatory vs inhibitory signals?

Excitatory signals promote firing of the postsynaptic neuron; inhibitory signals suppress it.

What are presynaptic and postsynaptic cells?

Presynaptic is the sending neuron; postsynaptic is the receiving neuron.

Name at least three functions of glial cells.

Myelination of axons, removal of toxic materials, protection of cell bodies, production of CSF, support of the blood-brain barrier, and nutrient support.

List glial cell types mentioned and one function each.

Astrocytes – support neurons and BBB; Oligodendrocytes – myelinate CNS axons; Microglia – immune-like debris cleanup; Ependymal cells – line ventricles and produce CSF.

What is the cell membrane composed of?

A phospholipid bilayer with hydrophilic heads and hydrophobic tails.

What are the main components of the cytoskeleton and their roles?

Microtubules – thickest; maintain shape and serve as transport highways. Actin filaments – thinnest; support movement, shape changes, and protein anchoring.

What are the main organelles found in most animal cells?

Membrane, cytosol, nucleus, mitochondria, ribosomes, rough and smooth endoplasmic reticulum, Golgi apparatus, and cytoskeleton.

What is the Golgi apparatus responsible for?

Modifying, sorting, and packaging proteins for secretion or delivery.

What does the rough endoplasmic reticulum do?

Contains ribosomes and synthesizes proteins.

What does the smooth endoplasmic reticulum do?

Synthesizes lipids and detoxifies chemicals.

What is the mitochondrion's function?

Powerhouse of the cell; produces ATP.

What is the function of dendritic spines?

Sites of excitatory synaptic input on dendrites.

What is the difference between grey matter and white matter?

Grey matter contains neuron cell bodies; white matter contains myelinated axons.

What is the Nissl stain used for?

Stains cell bodies blue/purple to reveal cytoarchitecture.

What is the Golgi stain used for?

Stains the entire neuron including soma, dendrites, and axons to reveal morphology.

What is the Weigert stain used for?

Stains axons (white matter).

What is electron microscopy?

Microscopy that uses electrons to image structures at high resolution.

What does patch clamp measure?

Patterns of action potentials in neurons.

What do ex vivo, in vivo, and in vitro mean?

Ex vivo means 'without life'; in vivo means 'within life'; in vitro means 'within glass.'

What are the three R's in animal research?

Replace, Reduce, Refine.

What does IACUC stand for?

Institutional Animal Care & Use Committee.

What is synaptic transmission?

The communication between neurons via the release and reception of neurotransmitters across a synapse.

What does cortical magnification mean?

Disproportionate representation of a sensory region (e.g., fovea) in the cortex.

What does topological mapping mean?

Preservation of neighborhood relationships when mapping sensory space to cortex.