L2 - Neurons and Glia

Reticular Theory

Argues that neurons are a fused, continuous “web” of interconnected fibers.

Neuron Doctrine

Argues that neurons are individual cells that communicate with each other by contact at synapses.

Soma

Region of the neuron that contains the nucleus and other organelles; processes information and signals to the next neuron.

Dendrite

Neurite that receives inputs from other neurons

Axon

Neurite specialized to conduct action potentials across the nervous system.

Axon hillock

The beginning of the axon that extends from the soma.

Axon proper

The middle part of the axon, covered in myelin sheath.

Axon terminal

The site where the axon comes in contact with other neurons and passes information on to them.

Axon collaterals

Branches of the axon

Recurrent collaterals

Axon collaterals that return to the original cell, or communicate with the dendrites of neighboring cells

Synapse

The point of contact between two neurons

Synaptic Cleft

The space between the presynaptic and postsynaptic membranes

Unipolar neuron

Neuron with one neurite extending from the soma

Bipolar neuron

Neuron with two neurites extending from the soma

Multipolar neuron

Neuron with multiple neurites extending from the soma

Spiny neurons

Neuron whose dendrites have spines

Aspiny neurons

Neuron whose dendrites do not have spines

Sensory neurons

Neurons that register a change in the environment (sensory information) from the environment and sends a signal to the brain.

Motor neuron

Neurons that communicate information from the brain to tissues and organs throughout the body, allowing for movement.

Interneuron

Neurons that serve as a relay between sensory and motor neurons in the nervous system. Form connections only with other neurons

Glia

Cells in the brain that insulate, nourish, support, and clean the brain

Myelinating glia

Provide layers of membrane that insulate and speed up axons called myelin.

Node of Ranvier

Periodical gaps in the myelin sheath where the axonal membrane is exposed.

Schwann cells

Myelinating glial cells found in the peripheral nervous system (PNS)

Oligodendroglial cells

Myelinating glial cells found in the central nervous system (CNS)

Microglia

Known as the brain’s “resident immune cells,” functioning as phagocytes to remove debris left by dead or degenerating neurons and glia.

Synaptic pruning

Microglia help remove unnecessary synapses during brain development and learning -> important for refining brain circuits.

Ependymal Cell

Lines the ventricles of the brain and central canal of the spinal cord and is essential for developing cerebral-spinal fluid.

Astrocytes

Star shaped glial cells that fill the space between neurons, support and nourish the brain, help form the blood-brain barrier, and regulate neural activity.

Immunohistochemistry

Use of antibody that binds to a protein target to detect and visualize target proteins within tissue sections

In Situ Hybridization

Uses labeled RNA probes to bind to complementary mRNA sequences, revealing gene expression patterns within individual cells.