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145 Cards in this Set
- Front
- Back
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What is abundant and divers, and makes up about half the volume of the nervous system? |
Neuroglia |
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The "Neuro" means |
Nerve |
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What "glia" mean? |
Glue |
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Which has a greater variety of neuroglial cell types the central nervous system or or the peripheral nervous system? |
CNS |
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What has limited our understanding of the the function of glial cells? |
Technical problems involves in isolating and manipulating their individual cells |
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What are the four types of neuroglia? |
Ependymal cells, Asrtocytes, Oligodendrocytes, Microglial |
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What does "Ependy" mean? |
a covering, to put on or over |
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What does "astro" mean? |
Star |
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What does "cyte" mean? |
Mature Cell |
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What does "Oligo" mean? |
Few |
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What does "Dendro" mean? |
Branches |
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What does "micro" mean? |
Small |
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What extends along the longitudinal axis of the spinal cord and brain? |
A fluid-filled central passageway |
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What fills the fluid filled passageway that extends along the longitudinal axis of the spinal cord and brain? |
(CSF) Cerebrospinal fluid |
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What does "cerebro" mean? |
Cerebrum, Brain |
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What does "spin" mean? |
Spine, Backbone |
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What does "al" mean? |
Pertaining to |
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How often does the cerebrospinal fluid circulate? |
Continuously |
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What does the cerebrospinal fluid provide? |
Protective cushion
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What does cerebrospinal fluid transport? |
Dissolved gasses, Nutrients, Wastes, Other Materials |
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What is the diameter of the internal passageway? |
It varies from one region to another |
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What is the narrow passageway in the spinal cord called? |
Central Canal |
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In several regions of the brain, what are the enlarged chambers formed by the passageway called? |
Ventricles |
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What lines the central canal and the ventricles? |
Ependymal cells |
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What are the ependymal cells that line the central canal and ventricles called when they form a simple cuboidal to columnar epithelium know as? |
Ependyma |
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What does ependyma lack that other epithelia has? |
Basement membrane |
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What do ependymal cells assist in? |
Producing CSF, Monitoring CSF, Circulating CSF |
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What are the three types of ependymal cells? |
Ependymocytes, Tanycytes, Specialized CSF-producing ependymal cells |
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What neuroglia has motile cilia that aid in the circulation of CSF and also microvilli? |
Ependymocytes |
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What is different about Ependymocytes in adults? |
cilia do not persist in all areas of the ventricles and central canal |
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What is the structure of an ependymocyte? |
Lone, slender basal process that branch and make contact with neuroglia |
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What are specialized, non-ciliated ependymal cells with microvilli on their apical surfaces. |
Tanycytes |
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Where are tanycytes found? |
Only in one brain ventricle |
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What are tanycytes thought to transport? |
Substances between the CSF and the brain |
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What functions may other regions of the ependyma have? |
Sensory, such as monitoring the composition of the CSF |
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What do stem cell lining the central canal and ventricles do during early embryonic development? |
Divide to give rise to neurons and all CNS neuroglia other than microglia. |
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What do ependyma in adults appear to contain? |
Stem cells that can divide to produce additional neurons |
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What is now being investigated in the division of stem cells in adults? |
The specific regulatory mechanism |
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What are the largest and most numerous neuroglia in the CNS? |
Astrocytes |
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How well do we understand the variety of functions in astrocytes? |
Poorly |
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What are five functions of Astrocytes? |
Maintaining the blood-brain barrier, Creating a 3demensional framework for the CNS, Repairing Damage Neural Tissue, Guiding neuron development, Controlling the interstitial environment
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Do compounds dissolved in circulating blood have fee access to the interstitial fluid of the CNS? |
No |
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Why must neural tissue be physically and biochemically isolated from the general circulation? |
Because hormones, amino acids, or other chemicals in the blood can alter neuron function. |
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What can hormones, amino acids, and other chemicals in the blood alter? |
Neuron function |
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What cells line the CNS capillaries? |
Endothelial cells |
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What do endothelial cells lining the CNS capillaries control? |
Chemical exchange between the blood and interstitial fluid |
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What isolates the CNS from the general circulation? |
(BBB) Blood-brain barrier |
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What cells create blood-brain barriers? |
Endothelial cells |
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What do the slender cytoplasmic extension of astrocytes end in? |
expanded "feet" |
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What do the expanded "feet" of an astrocyte do? |
they are processes that wrap around capillaries |
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What do the processes that wrap around capillaries (feet) form? |
a complete blanket around the capillaries |
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Where is the only place these (feet) processes or blankets around the capillaries can be interrupted? |
when other neuroglia come in contact with the capillary walls |
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What are the chemicals secreted by astrocytes somehow responsible for? |
Maintaining the special permeability characteristic of the capillary endothial cells |
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What are astrocytes filled with that extend across the breadth of the cell and its processes? |
mirofiliaments |
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What does the the extensive cytoskeleton help the astrocytes provide? |
A structural framework for the neurons of the brain and spinal cord |
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How often can a neural tissue in the CNS regain normal function after damage? |
Seldom |
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What can help in the repair of neural tissue? |
Astrocytes |
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What do astrocytes do when they move into an injury site? |
make structural repairs that stabilize the tissue to prevent further injury |
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What do astrocytes in the embryonic brain appear to be involved in? |
Directing both the growth and interconnection of developing neurons |
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What do astrocytes appear to adjust? |
The composition of interstitial fluid by several means |
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What do astrocytes regulate the concentration of? |
Sodium ions, Potassium ions, Carbon Dioxide |
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What is it called when astrocytes provide transportation for nutrients, ions, and dissolved gases between capillaries and neurons? |
Rapid-transit system |
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What do astrocytes control the volume of? |
Blood flow through the capillaries |
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What do astrocytes absorb and recycle some of? |
Neurotransmitters |
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What does the releasing of chemicals from astrocytes enhance or supress? |
Communication across axon terminals |
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What neuroglia is similar to an astrocyte in that is has slender cytoplasmic extensions, but has smaller cell bodies and fewer processes than astrocytes? |
Oligodedrocytes |
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What are the processes of oligodendrocytes generally in contact with? |
Exposed surfaces of neurons |
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What is the function of the oligodendrocytes processes ending at the neuron cell body? |
It has yet to be determined |
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What are many axons in the CNS completely sheathed in? |
Oligodendrocyte processes |
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What does the oligodendrocyte process insulate the CNS from? |
Contact with the extracellular fluid |
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During its maturation, what does the plasma membrane near the tip of each process of an oligodendrocyte expand to form? |
An enormous pad |
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When is the enormous pad at the tip of each process of an eligodendrocyte formed? |
During its maturation |
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What happens to the cytoplasm in this enormous pad? |
It becomes very thin |
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This enormous pad can also be called a flattened what? |
Pancake |
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When the flattened "pancake" somehow gets wrapped around the axolemma, what is formed? |
Concentric layers of plasma membrane |
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What is the membranous wrapping around the axolemma formed by flattened "pancake" called? |
Myelin |
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What does myelin serve as? |
An electrical insulation |
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What does myelin increase? |
The speed at which an action potential travels along the axon |
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What do oligodendrocytes cooperate to form along the length of an axon? |
Myelin sheath |
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What is an axon covered with a myelin sheath said to be? |
Myelinated |
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Each oligodendrocyte myelinates segments of several what? |
Axons |
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What are the fairly large areas of the axon that are wrapped in myelin called? |
Internodes |
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Typically, how long are internodes? |
1-2 MM |
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The small gaps of a few micrometers that separate adjacent internodes are called what? |
Nodes |
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What is another name for nodes? |
Nodes of Ranview |
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What part of the axon originates at the nodes? |
Collateral branches |
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Why do dissected myelinated axons appear glossy white. |
Primarily because of the lipids in the myelin |
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What are regions of the CNS dominated by myelinated axons known as? |
White matter |
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What are axons not completely covered by oligodendrocytes called? |
Unmyelinated |
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Unmyelinated axons are common where short axons and collaterals form what? |
A synapse with densely packed neuron cell bodies |
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What are the areas containing neuron cell bodies, dendrites, and unmyelinated axons with a dusky gray color called? |
Gray matter |
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Oligodendrocytes play an important role in structural organization by tying what together? |
Clusters of axons |
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How do oligodendrocytes improve the function of neurons? |
By wrapping axons within a myelin sheath |
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What is the least numerous and smallest neuroglia in the CNS? |
Microglia |
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What type of cell is Microglia? |
Phagocytic cell |
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What do their slender processes have? |
Many fine branches |
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What can microglia do through neural tissue? |
Migrate |
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What can microglia migrate through? |
Neural Tissue |
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When do microglia appear? |
Early in the embryonic development. |
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Where do microglia originate from ? |
Mesodermal stem cells |
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What are the mesodermal stem cells that the microglia originate from related to? |
Stems cells that produce monocytes and macrophages |
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When do microglia migrate into the CNS? |
As the nervous system forms |
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As the nervous system forms, where do the microglia migrate to? |
(CNS) Central nervous system |
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Where do microglia remain once they have migrated there? |
(CNS) Central nervous system |
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What do microglia act as in the CNS? |
Wandering janitorial service and police force |
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While remaining in the CNS, microglia acts as a janitorial service and police force by engulfing what? |
Cellular debris, Waste products, Pathogens |
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What are the cell bodies of neurons in the PNS that are clustered in masses called? |
Ganglia |
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What do the processes of neurogla do to neuronal cell bodies and most axons in the PNS? |
Completely insulate them from their surroundings |
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What are the two types of neuroglia? |
Satellite cells, Schwann cells |
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What surrounds the neuron cell bodies in ganglia? |
Satellite cells |
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What do satellite cells regulate? |
The environment around the neurons |
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What forms a thick, myelin sheath or indented fold of plasma membrane around peripheral axons? |
Schwann cells |
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What is another word for Schwann cells? |
Neurilemma cells |
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Whenever a Schwann cell covers an axon, what is the outer surface of the Schwann cell called? |
Neurilemma |
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What are most axons in the PNS, whether myelinated or unmyelinated shielded from by Schwann cells? |
Contact with interstitial fluid |
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How many segments of a single axon can a myelinating Schwann cell myelinate? |
One |
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What can enclose segments of several unmyelinated axons? |
Nonmyelinating Schwann cells |
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How much of the axon is a series of Schwann cells required to enclose? |
Along the entire length of the axon |
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Where does a Schwann cell first surround a portion of the axon? |
Within a grove of the axons cytoplasm |
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Once the Schwann cell surrounds the axon, what does it begin to do? |
Rotate around the axon |
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As the Schwann cell rotates, what is wound around the axon in multiple layers? |
Myelin |
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What do neurons respond to in a very limited way? |
Injury |
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What disperses in the cell body during a neurons response to injury? |
Nissl Bodies |
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What happens to the nucleus in the cell body during a neurons response to injury? |
It moves away from its centralized loacation |
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What increases in the cell body during the neurons response to injury? |
Its rate of protein synthesis |
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What will a neuron regain if it recovers and regains function? |
Normal appearance |
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The key to recovery of a neuron appears to be events in what? |
The axon |
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What happens to the affected axonal membrane if the pressure applied during a crushing injury produces a local decrease in blood flow and oxygen. |
It becomes unexcitable |
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How long will it take for the neuron to recover if the pressure applied by a crushing injury is alleviated after an hour or two? |
A few weeks |
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What effect is sever or prolonged pressure similar to? |
Cutting the axon |
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In the PNS, what does Schwann cells play a part in ? |
Repairing damaged nerves |
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What is it called when Schwann cells play a part in repaint damaged nerves in the PNS? |
Wallerian degeneration |
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During Wallerian degeneration what happens to the axon distal to the injury site? |
It degenerates |
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What part of the neuron degenerates during Wallerian degeneration? |
The axon distal to the injury site |
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What do macrophages do during Wallerian degeneration? |
They migrate into the area of injury and clean up debris |
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What migrates into the injury area to clean up the debris during degeneration? |
Macrophages |
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Do Schwann cells degenerate during Wallerian degeneration? |
No |
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What do Schwann cells do instead of degenerating during Wallerian degeneration? |
Proliferate and form a solid cellular cord that follows the path of the original axon |
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During a neurons recovery in the PNS what does the axon do into the site of injury? |
Grows |
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During a neurons recovery in the PNS what does the Schwann cell do? |
Wraps around the new formed axon |
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What happens if the axon grows alongside the appropriate cord of Schwann cells>? |
It may eventually reestablish its normal synaptic contacts |
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What happens if the axon stops growing or wanders off in some new direction? |
Normal function will not return |
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In what case is the growing axon most likely to arrive at its appropriate destination? |
If the cut edges of the original nerve bundle remain in contact |
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Can regeneration occur in the CNS? |
Yes |
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What are the 3 reason regeneration in the CNS is more complicated? |
Many more axons are likely to be involved, Astrocytes produce scar tissue that can prevent axon growth across the damaged are, Astrocytes release chemicals that block the regrowth of axons
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