10. glial cells III Flashcards
(18 cards)
What is the traditional view of synapses?
The traditional view of synapses is that they consist of just pre- and post-synaptic neuronal elements.
Define the tripartite synapse concept.
The tripartite synapse concept states that ~60% of excitatory synapses are surrounded by astrocyte processes.
How many synaptic contacts does each Bergmann glial cell interact with in the cerebellum?
Each Bergmann glial cell interacts with 2,000-6,000 synaptic contacts.
What happens to astrocytes in response to synaptic activity?
Astrocytes respond to synaptic activity with calcium increases.
What are gliotransmitters?
Gliotransmitters are substances released by astrocytes that affect neuronal function.
List the mechanisms of synaptic modulation.
- Glutamate clearance and recycling
- Gap junction coupling and signal propagation
- Gliotransmission
- Selective responsiveness
What role do astrocytes play in glutamate clearance?
Astrocytes remove glutamate from the synaptic cleft and convert it to glutamine using glutamine synthetase.
How do gap junctions contribute to astrocyte function?
Gap junctions allow calcium waves to propagate between astrocytes, enabling distant synapses to be modulated.
What is gliotransmission?
Gliotransmission is the release of ATP and other gliotransmitters by astrocytes that affects neighboring astrocytes and neurons.
True or False: Astrocytes can selectively respond to specific neurotransmitters.
True.
What is the structure of blood-brain barrier vessels?
Brain vessels have tight junctions between endothelial cells and are wrapped by astrocyte end-feet.
What is the significance of the blood-brain barrier’s structure?
It creates two isolated compartments (blood and brain parenchyma) and maintains proper ionic balance for neuronal function.
List some specialized transporters in the blood-brain barrier.
- ABC transporters
- Amino acid transporters
- Glucose transporters
- Ion channels
- Aquaporin-4
What occurs to astrocytes after traumatic brain or spinal cord injury?
Astrocytes become reactive and form a glial scar around the injury site.
What are the effects of the glial scar?
- Beneficial: Contains injury and prevents further damage
- Detrimental: Prevents axon regeneration across the injury site
What do astrocytes in the glial scar express?
Astrocytes in the scar express both growth-promoting and growth-inhibiting molecules.
What intrinsic neuronal factors prevent axonal regeneration?
Intrinsic neuronal factors such as the PTEN pathway prevent regeneration.
Fill in the blank: Blocking ______ can enable axons to grow through glial scars.
PTEN
