Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
167 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
Neurons deliver...
|
messages from the brain.
|
|
|
|
The function of the Ependyma is...
|
to filter things going into the brain. It lines the ventricles (spaces) of the brain. It also lines...
|
the spinal cord
|
|
|
The purpose of the Ependyma is to...
|
move Central Spinal Fluid through the ventricular system.
|
|
|
|
The ventricular system is...
|
the spaces within the brain and spinal cord where CSF flows.
|
|
|
|
The Choroid Plexus are...
|
specialized cells that make and secrete the CSF. They also play a significant role in...
|
blood brain barrier.
|
|
|
Ependyma are _____ cells that line brain ventricles.
|
epithelial
|
|
|
|
The 4 types of supporting cells (non-neuronal) are...
|
1- Astrocytes
2- Microglia 3- Oligodendrocytes 4- Schwann Cells or Lemmocytes |
|
|
|
The 3 types of neurons are:
|
1- Sensory neurons
2- Motor neurons 3- Interneurons |
|
|
|
Sensory Neurons are...
|
Specialized neurons that detect change in the external OR internal environment and sends info about these changes to...
|
Central Nervous System.
|
|
|
Motor Neurons are...
|
neurons that control contraction of muscle or secretion of a gland.
|
|
|
|
Interneurons are...
|
neurons located entirely within the CNS. They communicate...
|
between cells.
|
|
|
4 parts of the neuron:
|
1- Dendrites: extensions from Cell Body.
2- Cell body (or perikaryon) 3-Axon 4- Terminal boutons (or buttons or bulbs) |
|
|
|
The function of dendrites are to...
|
receive SENSORY information from other neurons or receptors. The cell has 1 or more.
|
|
|
|
The function of the cell body of the neuron is...
|
the SYNTHESIZING center for the neuron. It decides what to do with the information it receives. i.e. it is the brain of the neuron structure. It contains a...
|
nucleus. It is also receptive to stimuli.
|
|
|
The function of the axon is...
|
to transmit info from the cell body to the terminal boutons. i.e. it conveys the message the cell body decided on.
*msg = action potential. |
|
|
|
The axon can be ______ which means surrounded by a fatty insulating sheath, and conducts impulses fast.
|
myelinated. Or it can be non-myelinated which means it lacks the sheath and conducts impulses slowly.
|
Myelin is white. It is the white matter.
|
|
|
The _____ is a single process that extends from the cell body.
|
Axon
|
|
|
|
When the ________ receives the "message" (action potential) it releases neurotransmitters from the terminal boutons.
|
axon terminal. They are located at the end of the axon.
|
The neurotransmitters are received by other neurons.
|
|
|
Connect these terms:
Integration Zone Axon Input Zone Axon terminals Output zone Dendrites Conduction Zone Cell Body |
Integration Zone = Cell Body
Input Zone = Dendrites Conduction Zone = Axon Output Zone = Axon terminals |
|
|
|
Neuron categories are based on ______ variations
|
Structural. Neurons can have the same components but be labelled differently based on structure.
|
These structural variations occur especially in the sensory systems.
|
|
|
Neuron categories include:
|
Multipolar (what we normally think of as a neuron, motor neuron, pyramidal cell, etc.
Bipolar (Cochlea, retina) Monopolar/unipolar (Somatic and visceral sensory fibers) |
|
|
|
Name neuron or nerve:
Single cell |
Neuron
|
|
|
|
Neuron or nerve:
Information travels in one direction. |
Neuron
|
|
|
|
Neuron or nerve:
Groups of fibers travelling together. |
Nerve
|
|
|
|
Neuron or nerve:
Information can go in either direction (i.e. tell muscles to move, or receive sensory info) |
Nerve
|
|
|
|
_____ are axons of neuron (sometimes used with dendrites)
|
Nerve fibers
|
|
|
|
An afferent fiber is one that sends signals...
|
In. These are...
|
Sensory
|
|
|
An efferent fiber sends signals...
|
out. These are...
|
Motor
|
|
|
Supporting cells in the nervous system are called...
|
neuroglia "nerve glue"
|
|
|
|
The supporting cells provide _____ support.
|
Structural. There is very little connective tissue in the nervous system. These non-neuronal cells provide support.
|
|
|
|
Neuroglia form the _____ sheathes of axons and act as _____.
|
Myelin.
Insulators. |
|
|
|
The Supporting cells control supply of...
|
Nutrients.
|
|
|
|
The supporting cells act as ______ and destroy ______.
|
Housekeepers
Dead neurons. |
|
|
|
Neuroglia differ from neurons for 3 reasons:
|
1- They have no action potential and cannot transmit nerve impulses.
2- They are able to divide (and are the source of tumors of the nervous system because of this) 3- They do not form synapses. |
|
|
|
CNS Glial cells include:
|
Oligodendrocytes, astrocytes, and microglia.
|
|
|
|
The 4 functions of the astrocytes (star shaped cells) are:
|
1- Recycle neurotransmitters
2- Secrete neurotrophic factors (neural growth factor) that stimulate growth and maintenance |
3- Dictate number of synapses formed on neuronal surfaces (modulate how neurons talk to one another).
4- Maintain appropriate ionic composition of extracellular fluid surrounding neurons (absorb excess potassium and other larger molecules) |
|
|
Astrocytes regulate the...
|
Blood Brain Barrier.
|
|
|
|
_______ are the smallest of glial cells.
|
Microglia.
|
|
|
|
______ represent intrinsic immune effector cells of the CNS.
|
Microglia.
|
|
|
|
The 3 functions of the Microglia are:
|
1- Underlie the inflammation response that occur following damage to the central nervous system.
2- Protect against invasion of microorganisms. |
3- Remove debris left by dead or degenerating neurons and glia.
|
|
|
The 2 functions of Oligodendrocytes:
|
1- Forms myelin sheaths around brain and spinal cord axons.
The myelin is an electrical insulator, and wraps in multiple layers. |
2- Provide support to axons.
|
|
|
The bare spots that the myelin does not cover on the brain and spinal cord axons are called...
|
Nodes of Ranvier
|
|
|
|
The supporting cells in the CNS (central nervous system. only the brain and spinal cord) are:
|
Astrocytes
Microglia Oligodendites |
|
|
|
The supporting cells that are in the PNS (Peripheral Nervous System) are:
|
Schwann Cells or Lemmocytes.
|
|
|
|
_______ wrap individually around the shaft of peripheral axons and form a layer of myelin sheath along segments of the axon.
|
Schwann Cells or Lemmocytes.
|
|
|
|
Schwann cell membrane, which forms the myelin sheath, is composed primarily of...
|
lipids. The lipids serve as an insulator, thereby _______ the transmission rate of action potentials along the axon.
|
speeding
|
|
|
Which of the following is notcharacteristic of glial cells?
A. Prodution of action potentials B. Immune responses of the nervous system C. Production of the myelin sheaths of axons D. Modulating the growth of developing or damaged neurons E. Buffering extracellular concentrations of some ions and neurotransmitters |
A. Production of action potentials
|
|
|
|
Which part of a neuron is primarily characterized as the information-receiving component?
A. Axon B. Presynaptic terminal C. Cell body D. Dendrite E. Myelin |
D. Dendrite
|
|
|
|
Channelopathies are disease which are caused by problems with _________
|
Ion channels.
|
|
|
|
The __________ is the difference in electrical charge inside and outside a cell which is at rest.
|
Resting membrane potential. This difference occurs across the _______ of an excitable cell (muscle, neuron).
|
Membrane
|
|
|
Most neurons have a resting membrane potential of ______ mVolts.
|
-70
|
|
|
|
The negative charge of the neuron is maintained by a ___________ cell membrane.
|
selectively permeable. Which keeps in organic ______ and negatively charged _______.
|
anions
proteins. The proteins are unable pass through the membrane, so they cannot leave the cell. |
|
|
Label the following ions as many or few as they occur inside the neuron cell:
Na+ K+ Cl- Ca2+ Negative proteins |
Na+ = few
K+ = many Cl- = few Ca+ = few Negative proteins = many |
|
|
|
_________ are membrane proteins which allow the passage of certain ions depending on size and charge.
|
Ion channels
|
|
|
|
The negative resting potential of the neuron is maintained by 3 factors:
|
1- Selectively permeable membrane.
2- Ions moving to equilibrium (passively) 3- Na/K Pump (active) |
|
|
|
The intracellular fluid of the neuron is negatively charged because of large _________ that cannot pass through the cell membrane to get outside the cell.
|
protein anions.
|
|
|
|
________ channels allow K+ cations to pass through the membrane in to the intracellular space (down their electrostatic gradient, the positive K+ are attracted to the negative fluid in the neuron).
|
Passive potassium (K+). The __________ pushes K+ out of the cell, then a balance of forces is reached (at -60mV).
|
concentration gradient.
|
|
|
Na+ cations from the extracellular fluid leak (sneak) through the membrane to go down their electrostatic (attracted to the negative intracellular fluid) and concentration gradients (few Na+ inside, a lot outside) into the cell. The active _______ pushes them back out of the cell.
|
Na/K pump.
|
|
|
|
The Na/K pump sends out ______ Na+ for _____ K+ coming in.
|
3
2 This process requires ______. |
ATP.
|
|
|
____ to_____ % of ATP in the brain is used for the Na/K pump
|
50
70 |
|
|
|
Excitable cells (neurons) have an intracellular electrical charge known as the ________________
|
resting membrane potential. Which at rest is negative.
|
|
|
|
Resting membrane potential is due to the movement of _______ across the semi-permeable membrane of the axon.
|
ions
|
|
|
|
The electrical potential of the resting membrane potential is energy waiting to be released = ______ conducted from one neuron to the next
|
message
This is the ____________ |
Action Potential
|
|
|
A(n) ___________ is the basic mechanism for transmission of info in the nervous system and muscles.
|
Action Potential
|
|
|
|
The action potential is caused by ________ of membrane past a certain threshold followed by a __________.
|
depolarization
repolarization |
|
|
|
The "All-or-none" response occurs only if a cell is _________ past a certain threshold.
|
depolarized
|
|
|
|
The chain reaction of action potential is known as __________
|
Propagation.
Action potential at one site causes _________ at other sites and brings those sites to threshold. |
depolarization
|
|
|
The events of an Action potential occur in 5 stages:
|
1- Depolarization
2-Threshold reached 3- Action potential 4- Repolarization/hyperpolarization 5- Refractory state |
|
|
|
In depolarization, the membrane potential becomes _____ negative, when compared to the resting membrane potential
|
LESS.
(It does not need to become positive, only less negative). |
|
|
|
The _________ is reached when the membrane potential (charge of cell) becomes such that an action potential is inevitable.
|
threshold
|
|
|
|
After a threshold has been reached, a(n) _________ electrical charge is propagated down the axon.
|
all-or-none. This stage is called _________
|
Action potential
|
|
|
When action potential occurs, the membrane potential becomes so less negative, the cell can _______ and be positive relative to outside.
|
overshoot.
|
|
|
|
At ________ the membrane potential heads to original resting potential.
|
repolarization.
At this point the cell typically becomes more negative relative to the resting potential, which is called ________ |
hyperpolarized
|
|
|
The __________ period is when the cell is going back to resting potential.
|
Refractory
|
|
|
|
During __________ excitable cells are incapable of producing normal action potential.
|
refractory
|
|
|
|
There are two states of refractory. These are:
|
Absolute Refractory
Relative Refractory |
|
|
|
At ___________ no amount of stimulation can induce an action potential (immediately after action potential).
|
absolute refractory
|
|
|
|
At _________ very strong stimulation can induce another action potential (not immediately after the action potential, but prior to return to resting potential)
|
relative refractory
|
|
|
|
How does ion movement cause depolarization?
|
Stimulus results in a slight positive charge, which allows some voltage-gated _____ channels to open, leading to depolarization.
|
Na+
|
|
|
What happens to the ion movement when the threshold is reached?
|
Additional (a lot of) voltage-gated Na+ channels open, causing rapid change in charge.
|
|
|
|
After the threshold is reached, the intracellular fluid can now be positively charged due to the large influx of Na+ ions. This generates _________
|
action potential
|
|
|
|
During the __________, the Na+ channels close, which terminates the AP and the voltage-gated K+ channels open.
|
refractory state.
The positive charges inside the cell push K+ cations. Excess K+ channels open leads to a _________ (more negative cell membrane charge relative to resting state.) |
hyperpolarization.
|
|
|
When the cell membrane repolarizes and returns to resting potential, the ______ charge reaches equilibrium with electrostatic and concentration gradients.
|
K+
The cell membrane is now ready for another _________. |
Action potential.
|
|
|
Where is depolarization initiated?
|
Spike-initiation zone. Sensory nerve endings OR axon hillock.
|
|
|
|
Axon Potential ___________ is when depolarization occurs progressively as it moves down the axon.
|
Conduction
|
|
|
|
Action Potential Conduction occurs faster with the presence of the ___________
|
myelin sheath.
Myelin is the lipid insulator of neuronal axons. 2 types of myelinated cells are: |
1- Schwann cells
2- Oligodendrites |
|
|
Unmyelinated Axon Action Potential Conduction is slow because the signal is _______
|
lost.
|
|
|
|
On myelinated neurons, the action potential conduction occurs at ___________
|
the nodes of Ranvier, which are breaks in the myelin sheath. The voltage gated Na+ channels are _________ concentrated at the nodes.
|
highly
|
|
|
________ Conduction: nerve impulse jumps from node to node. Fast.
|
Saltatory
|
|
|
|
__________ is a condition that occurs when the myelin sheath is lost.
|
Muscle dystrophy
|
|
|
|
A _______ is a site where info is transmitted from one cell to the next.
|
synapse
|
|
|
|
A neuron or cell sends info via ________ synapse or _______ synapse.
|
electrical
chemical |
|
|
|
________ is the basic mechanism of transmission of information in excitable tissue (cells and muscles)
|
Action potential
|
|
|
|
The direction of flow in a synapse is _____ to ______.
|
neuron
target cell |
|
|
|
The 3 elements that make up a synapse are:
|
1- Presynaptic neuron or nerve terminal
2- Postsynaptic neuron 3- Link between these two cells |
|
|
|
The __________ of a synapse is the source of information. The signal can be chemical or electrical.
|
Presynaptic neuron or nerve terminal
|
|
|
|
The _______ of a synapse is the target. It is the dendrite, cell body, or target cell receiving the synaptic input.
|
Postsynaptic neuron
|
|
|
|
At the _________ is where the electrical current or chemical messenger flows in to.
|
Postsynaptic neuron
|
|
|
|
The link between the two cells can be either a ________ or ______
|
gap junction
synaptic cleft |
|
|
|
The gap junction is _______.
|
electrical
|
|
|
|
The synaptic cleft is ________
|
chemical
|
|
|
|
What are the 3 names that identify the contact region between the presynaptic and postsynaptic neurons?
|
Axosomatic
Axodendritic Axoaxonic |
|
|
|
Axosomatic is the axon contacting the ______
|
cell body
|
|
|
|
Axodendritic is the axon contacting the ________
|
dendrite
|
|
|
|
Axoaxonic is the axon contacting the ______
|
axon. (less common)
|
|
|
|
Location of synapses has implications for how signals can be _______ or ______
|
enhanced
inhibited |
|
|
|
__________ synapses have gap junctions and cells that are "electrically coupled" i.e. that happen almost simultaneous.
|
Electrical
|
|
|
|
_________ are made of proteins in membrane that form pores between two cells. It is a connexon-formed channel by 6 connexins.
|
Gap junction
|
|
|
|
The key feature of electrical synapses is that it is very ________ transmission
|
fast
|
|
|
|
The function of electrical synapses are _______ and __________.
|
Rapid (instantaneous) signaling
Synchronize electrical activity between neuron populations. |
|
|
|
Examples of areas that need synchronized electrical activity between neurons are ______ neurons that synchronize breathing, and __________ neurons which synchronize a "surge" or release.
|
Brainstem
hormone secreting |
|
|
|
______ synapses are found in retina, cardiac muscle, smooth muscle, and receptor cells. All things that need coordination of contraction.
|
Electrical
|
|
|
|
In ________ synapses, ions flow through gap junction channels, while in _________ synapses, neurotransmitters are released and ions flow through postsynaptic channels.
|
electrical
chemical |
|
|
|
___________ is most common cell-cell communication in the nervous system.
|
Chemical synapse
|
|
|
|
The 3 structural elements of chemical synapse are:
|
1- presynaptic membrane
2- synaptic cleft 3- postsynaptic membrane |
|
|
|
___________ synapse are found between neurons, neuron-muscle cells, and neuron-glandular epithelium.
|
Chemical
|
|
|
|
________ is required for functional integrity of chemical synapse.
|
Ca2+ (calcium)
|
|
|
|
8 steps of the release of transmitter from chemical synapse:
|
1- Action potential approaches axon terminal (depolarized membrane)
2- Activates voltage-sensitive Ca2+ channels to open 3- Ca2+ rushes into presynaptic cell terminal 4- Elevated Ca2+ triggers transmitter vesicle mobilization, docking, and fusion with presynaptic membrane 5- Transmitter released, diffuses across synaptic cleft via exocytosis. 6- Chemical message (transmitter) binds postsynaptic receptors 7- Binding to receptor which opens up an ion channel 8- Change in membrane potential of post-synaptic cell (can be excitatory or inhibitory) |
|
|
|
Excitatory change in the postsynaptic cell is when the neurotransmitter _________ postsynaptic cell.
|
depolarizes
|
|
|
|
_________ change in the postsynaptic cell is when the neurotransmitter hyperpolarizes postsynaptic cell.
|
Inhibitory
|
|
|
|
During step 7 of the release of transmitter from chemical synapse, when they bind to the receptor there are two paths that can occur. 1) causes fast chemical synaptic transmission. 2) causes slow chemical synaptic transmission.
|
1) They bind to the receptor, causing the ion channel opens, and Na+ enters the postsynaptic membrane, causing depolarization. Fast.
2) They bind to a G-protein coupled receptor and indirectly affects channel opening. Slow. |
|
|
|
The fast chemical synaptic transmission is also called ________
|
Ionotropic or ligand-gated ion channels. Occurs at about 2 msec to max. response.
|
|
|
|
The slow chemical synaptic transmission is also called _______
|
Metabotropic. Occurs hundreds of msec to max. response.
|
|
|
|
What are the 6 stages of the life cycle of the transmitter (XMTR)?
|
1- Synthesis of transmitter
2- Packaged into vesicles at rest vesicles near axon terminals. Action potential stimulate activity. 3- Dock and fuse of vesicles with presynaptic plasma membrane. 4- Exocytosis releases transmitter. 5- Diffusion of XMTR across cleft, binds receptor. Changes postsynaptic Vm. 6- XMTR removed from synaptic cleft. |
|
|
|
What are the 3 ways the neurotransmitter is removed from the synaptic cleft to stop the response?
|
1- Diffusion away from cleft.
2- Destroyed enzymatically (ACh and NE) 3- Reuptake into presynaptic cell of glial cell (GLU and GABA) |
|
|
|
What are the 3 fates of neurotransmitters?
|
1- Binds to receptor on postsynaptic membrane to generate post synaptic potential (PSP)
2- Binds to autoreceptor (Presynaptic membrane. Feedback control). 3- Removed from synaptic cleft to stop the response. |
|
|
|
The XMTR causes change in postsynaptic cell membrane potential (Vm). This is called:
|
Post synaptic potential or PSP.
|
|
|
|
If an Excitatory Postsynaptic Potential (EPSP) is sent, the postsynaptic cell is_________. Leads to increased Vm, moves toward threshold.
|
Depolarized.
|
|
|
|
If an Inhibitory Postsynaptic Potential (IPSP) is sent, the postsynaptic cell is _________. Leads to decreased Vm and moves away from threshold.
|
Hyperpolarized.
|
|
|
|
__________ is the process by which multiple synaptic potentials combine within one post synaptic neuron. (EPSP and IPSP)
|
Synaptic Integration
|
|
|
|
__________ is the coordination of neuronal activity.
|
Neuronal integration
|
|
|
|
An example of neuronal integration is when EPSPs are _________ to produce significant postsynaptic depolarization.
|
added together
|
|
|
|
An example of neuronal integration is when EPSP and EPSP are added together, which ______ EPSP or prevents reaching threshold.
|
reduces.
The is called algebraic. |
|
|
|
________ and ________ summation are forms of neuronal integration.
|
Spatial and Temporal
|
|
|
|
___________ is the integration of information coming from various sources impinging on various location of the postsynaptic cell. Simultaneous input. (i.e. multiple synapses sending signals at the same time to the same place.)
|
Spatial summation.
|
|
|
|
_________ is a series of action potential arriving on a single presynaptic nerve fiber. Allows frequency of input to influence postsynaptic response. (i.e. One synapses sends a series of action potentials right after one another, so they build up until they reach the threshold).
|
Temporal summation
|
|
|
|
__________ is the sum of all temporal and spatial inputs coming into a postsynaptic cell (local responses).
|
Algebraic summation
|
|
|
|
During algebraic summation, the decision to generate action potential is made at __________ near axon hillock.
|
spike initiation zone
|
|
|
|
An example for EPSP and IPSP is the _______ reflex. EPSP to cause contraction of agonist and IPSP to inhibit contraction in antagonist.
|
Knee-jerk
|
|
|
|
________ have small energy stores, they do not survive long without O2, and they do not regenerate and have limited ability to replace themselves.
|
Neurons
|
|
|
|
Nerve fibers in the ______ do not regenerate because the conditions (glia) inhibit regeneration.
|
CNS
|
|
|
|
Nerve fibers in the _____ can regenerate under certain conditions.
|
PNS
|
|
|
|
______ are particularly susceptible to damage.
|
Neurons
|
|
|
|
The order of sensitivity from weakest to strongest is:
|
Neurons;
Oligodendroglia; Astrocytes; Microglia |
|
|
|
Transient loss of function of neurons is due to 5 things:
|
1- Edema
2- Constant pressure 3- Anoxia 4- Cold 5- Compression and crushing injury |
|
|
|
Permanent neuronal degeneration is due to _____ and _____.
|
Normal aging processes and disease processes
|
|
|
|
4 responses to neural damage are:
|
1- Reorganization
2- Regeneration 3- Survival 4- Neurogenesis |
|
|
|
The 3 responses to neural damage that repair are:
|
1- Regeneration
2- Survival 3- Neurogenesis |
|
|
|
_________ is when brain circuitry finds a new route to generate the original function.
|
Reorganization
|
|
|
|
________ is regrowth of axons from neurons located int he PNS or cells in the CNS which send their terminals to the periphery.
|
Regeneration
|
|
|
|
_________ is when neurons in the CNS are damaged but are able to keep alive.
|
Survival
|
|
|
|
________ is the production of new neurons to replace lost or worn out cells. Is a rare mechanism.
|
Neurogenesis
|
|
|
|
_________ is the process of the when damage to peripheral neuron axon which occurs at the site of trauma and continues to distal end of neuron. Axon and associated myelin breakdown over 3-5 days. Phagocytosis of axon, myelin, etc.
|
Wallerian degeneration
|
|
|
|
The regeneration of Wallerian degeneration has 5 steps:
|
1- At injury site, Schwann cells divide and bridge gap between two stumps.
2- Macrophages come in to digest the broken pieces of myelin. 3- Axon terminal connection to the muscle is lost. 4- At the proximal stump, branching or sprouts form. One will persist and grow towards distal stump. Schwann cells produce growth promoting factors. 5- Once axon reaches the end tissue (muscle), then Schwann cells start myelin production. |
|
|
|
In step 4 of regeneration, the growth cone will join with the distal (degenerated portion of the severed nerve IF _________. Crushed nerves are faster at regeneration because the distal damaged segments provide a guide for the growth gone.
|
it is close enough
|
|
|
|
After ________ occurs, the axon diameter is reduced (80% of what it was), so nerve does not conduct as fast as before, and internode segments are smaller.
|
regeneration
|
|
|
|
__________ is the loss of neuron connection to the muscle. Muscle no longer has input, cannot do its job, and starts to generate proteins in relation to growth.
|
Chromatolysis
|
|
|
|
The basic 3 steps of peripheral nerve regeneration (Macrophages and Schwann cells are key players):
|
1- Macrophages remove debris and myelin from degenerating neuron.
2- Schwann cells proliverage (First, produce factors which guide axon and promote growth. Then bridge gap) 3- Proximal axon stump begins to form growth cones and interacts with Schwann cells. |
|
|
|
Peripheral nerve injury also impairs _________
|
target cell
|
|
|
|
Severing a neuron which innervates a muscle causes ________.
|
Neurogenic atrophy (decrease in muscle mass as a result of nerve injury)
|
|
|
|
In survival, following damage to cells in the CNS, ______ grow, _______ degenerate, and loss of synapses.
|
Glial
Dendrites |
|
|
|
In recovery after survival, some axon and dendrite growth is seen, but recovery in CNS is ______ compared to PNS.
|
Very limited
|
|
|
|
Why is CNS recovery/regeneration limited compared to PNS? 5 reasons:
|
1- Lots of coordination required between glia and neurons
2- Re-engage developmental processes to generate new axons 3- Injury leads to lots of cell death and necrosis 4- Brain tissue damage is seen as inflammation, microglia respond and actively suppress growth, synapse formation. 5- Glial cells overgrow - Glial scarring. |
|
|
|
________ prevents trophic factors from reaching and supporting damaged neurons. Glia produce axon growth inhibiting signals.
|
Glial scarring
|
|
|
|
Regeneration in the CNS is limited because 3 reasons:
|
1- Myelin degeneration
2- Microglia acting as phagocytes and removing debris. But don't remove all of it. 3- Inhibitory factors produced by glial cells disrupt axon extension. |
|
|
|
______ is a controversial yet promising field. But the mechanisms are relatively unknown. Birds, frogs, fish are more capable of regenerating adult neurons, and mammals can make new neurons in the olfactory bulb and hippocampus.
|
Neurogenesis
|
|
|
|
Neurogenesis depends on __________ of a neural stem cell. After injury, stem cell proliferates and differentiates into neurons which integrate with the tissue and make connections with existing cells.
|
maintenance
|
|
