Week 2: Cells of the Nervous System Lecture

Vocabulary flashcards defining key structures, supporting cells, network concepts, and barrier functions covered in the Cells of the Nervous System lecture.

Central Nervous System (CNS)

The part of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

All nerves that relay information between the central nervous system and the body.

Neuroglia

Supporting cells in the nervous system that constitute about half the volume of the CNS.

VGG

An example of an artificial neural network that mimics biological neural network structure and is useful for vision-based applications and brain research.

Soma (Cell Body)

The part of a neuron containing the nucleus and most internal structures; the nucleus holds DNA which directs protein synthesis critical to cell functioning.

Mitochondria

Organelles that convert nutrients into ATP for the cell's functions.

Microtubules

Structures responsible for axoplasmic transport, moving substances along the axon from the cell body to terminal buttons.

Dendrites

Thin, branching fibers (from the Greek for 'tree') that receive information from other cells; typically shorter than axons and may have dendritic spines.

Axon

A single, thicker, longer fiber that carries information away from the cell body via the action potential; begins at the axon hillock.

Myelin sheath

An insulating lipid material found on many neurons that prevents signal spreading to neighboring neurons and speeds transmission.

Nodes of Ranvier

Small gaps of unmyelinated axon between myelin segments, found only in the CNS, that help speed neurotransmission.

Terminal buttons

Knobby structures at the axon's end where synapses form and neurotransmitters are released via synaptic vesicles.

Synapse

A junction where information is transmitted from one neuron to another, which can form on either the cell body or dendrites.

Multipolar neurons

The most common type of neuron in the brain, characterized by many branching dendrites; includes motor neurons whose cell bodies are in the CNS but whose axons project into the PNS.

Bipolar neurons

Neurons having two axon-like processes (one toward dendrites, one toward terminal buttons), typically associated with visual and auditory sensory systems.

Unipolar neurons

Neurons characterized by a single axonal stalk that branches into both dendrites and terminal buttons, typically associated with somatosensory systems and found deep in the skin.

Astrocytes

CNS supporting cells that provide nutrients to neurons, regulate extracellular chemical composition, isolate synapses to limit neurotransmitter dispersion, perform phagocytosis of damaged cells, and critically form the blood-brain barrier.

Microglia

The smallest glial cells, making up $5-10\%$ of brain cells, which serve as the primary active immune defense of the CNS by acting as phagocytes.

Oligodendrocytes

CNS supporting cells that form the myelin sheath by wrapping paddle-shaped processes around axon segments, leaving gaps called nodes of Ranvier.

Schwann cells

PNS supporting cells that form myelin in the PNS by wrapping their entire cell body around peripheral neurons, with one cell forming one myelin segment and leaving no nodes of Ranvier.

Blood-Brain Barrier

A functional barrier formed by astrocytes around brain blood vessels with very few gaps, maintaining electrolyte balance and protecting the brain from toxins.

Paul Ehrlich

The researcher who demonstrated the existence of the blood-brain barrier by showing that blue dye injected into the bloodstream stained other organs but not the brain.

Methylene blue

A substance notable for randomly crossing the blood-brain barrier, increasing oxygen in the bloodstream, and having medical uses such as treating cyanide poisoning.

Area postrema

A region of the medulla where the blood-brain barrier is weak, allowing small amounts of ingested toxins to signal the brain to induce vomiting.

L-dopa (levodopa)

A dopamine precursor discovered in the 1950s that crosses the blood-brain barrier and is converted to dopamine in the brain, used as the standard treatment for Parkinson's disease.