Cells of the Nervous System Flashcards
Phospholipid bilayer (membrane)
Polar “head” contains phosphate, nonpolar “tail” contains hydrocarbon
Surrounds the whole cell (separating inter- and intracellular fluid)
Heads are hydrophilic, tails are hydrophobic
Membranes are self-organized, and are not fixed (membrane fluidity)–allows us to insert proteins into the fluid membrane
Embedded proteins give neurons their special properties
Neuron
The basic unit of the nervous system
Consists of a cell body, receptive extensions (dendrites) and transmitting extension (axon)
Come in many different varieties based on size, shape, function, chemistry, etc.
Soma
Cell body
Region of the neuron defined by the presence of the cell nucleus
Receives and integrates inputs (with dendrites)
Dendrite/dendritic arbor or tree
Along with cell body, receive and integrate inputs
Dendrites are really extensions of the soma
Can synthesize proteins (axons cannot)
Dendrites have dendritic arbors (tree-like, tapered extensions)
Axon
A single extension from the nerve cell that carries nerve impulses from the cell body to other neurons
Conducts action potential
Like a water pipe, constant diameter throughout its length until getting to the axon terminals, which end in terminal boutons aka synaptic knobs aka synaptic terminals
Axon hillock
A cone-shaped area from which the axon originates out of the cell body
The integration zone of the neuron
With initial segment, generates axon potential
Axon collateral
A branch of an axon from a single neuron
Always leaves the axon at right angles
Synapse
The tiny gap between neurons where information is passed from one to the other
Presynaptic terminal arbor
??
Presynaptic terminal, boutons, buttons, or knobs
Transmits to target cells
End of an axon or axon collateral which forms a synapse on a neuron or other target cells
Synaptic vesicles
A small, spherical structure that contains molecules of neurotransmitter
Sacs of membranes that transmit chemicals (neurotransmitters)
Neurotransmitter
The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons
Synaptic cleft
The space between the presynaptic and postsynaptic elements
Synaptosome
Body of the synapse
Synapse = marriage; synaptosome = spouses
Neurites (or processes)
Leave the cell body
Include dendrites and axons
A typical neuron has varying numbers of dendrites and a single axon
Unipolar neuron
A nerve cell with a single branch that leaves the cell body and then extends in two directions
One is the receptive pole, the other end is the output zone
Bipolar neuron
A nerve cell that has a single dendrite at one end and a single axon at the other end (space between dendrite and cell body, long linear cell)
Multipolar neuron
A nerve cell that has many dendrites and a single axon (no space between dendrites and cell body–looks like stereotypical neuron)
Central nervous system
The portion of the nervous system that includes the brain and the spinal cord
Peripheral nervous system
The portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord
Glia
Come in several different varieties
Allow for optimizing specialized functions
Five to ten times as many glia as neurons in the CNS
Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain
Astrocytes
A star-shaped glial cell with numerous processes (extensions) that run in all directions
Most numerous glial cell
Form the supporting matrix of the nervous system
Fairly large
Serve various functions: carry substances to and from blood vessels to neurons and back, carry metabolic waste products from neurons back to the blood, form scar tissue in the case of injury
Important for regulating environment of neurons
Buffer extra-cellular fluid for neurons
Not always helpful, can be implicated in the development of toxins that kill neurons
Microglia
Extremely small glial cells that remove cellular debris from injured or dead cells
The principle immune element of the brain (brain is immunologically privileged)
Serve as phages, attack things in the brain
Seem to be implicated in Alzheimers (killing neurons–microglia gone nuts, neurons get tagged for destruction)
Oligodendroglia
Glial cells that form myelin in the central nervous system
One oligodendrocyte can myelinate multiple axons
Schwann cells
The glial cell that forms myelin in the peripheral nervous system
Schwann cells can only make one section of myelin
Peripheral nerves do regenerate because Schwann cells provide myelin; central nerves do not
Myelin Sheath
The fatty insulation around an axon, formed by glial cells, that improves the speed of conduction of nerve impulses
Functions of neurons: reception and integration of inputs
Dendrites and soma
Functions of neurons: generation of action potential (nerve impulse)
Axon hillock
Functions of neurons: conduction of action potential
Axon
Functions of neurons: synaptic transmission
Transmit information to target cell (neuron, muscle, gland)
nerve terminals
