Glial Cells Flashcards
What are four main functions of glial cells?
- surround neurones and provide support
- supply them with nutrients
- insulate neuron and facilitate synaptic transmission
- destroy and remove unwanted debris
What is the O2A progenitor?
The progenitor to astrocytes and oligodendrocytes.
How does differentiation of oligodendrocytes work?
Start as oligodendrocyte precursors (NG2) then they become immature oligodendrocytes (O4) then mature oligodendrocytes.
What are schwann cells?
Myelinating cells of the PNS
What cells give rise to Schwann cells?
Neural crest cells give rise to schwann cell precursors.
How do you get astrocytes?
Neural stem cells undergo specification to an astrocyte precursor which undergoes differentiation to become an astrocyte.
What tiles the parechyma?
Microglia
What happens when the brains homeostasis is disrupted?
Microglia equipped with a repertoire of immune sensors and reactants allowing rapid reaction to any disruption
What is the microglial progenitor?
Erythromyeloid progenitor
What are microglia for first 2 weeks of a human life?
Known as Ameoboid cells- they gradually acquire a ramified state and shape of microglia
What are astrocyte functions?
- neurogenesis and gliogenesis
- neuronal guidance in brain development
-regulates synaptogenesis and synaptic maturation
how many axon-dendritic synapses are surrounded by astrological membranes?
60%
How many perforated synapses are surrounded by astrocytes?
~80%
Are astrocytes excitable cells?
Yes, in response to stimulation their endoplasmic recticulum release calcium stores.
How do astrocytes regulate neuron excitability?
Through gliotransmitters
What effects do astrocytes have on glutaminergic signaling?
astrocytes participate on glutamate clearance and provision.
Name a gliotransmitter….
ATP
How does ATP effect the synapse?
Through paracrine activity through calcium waves in astrocytes and suspresses synaptic transmission
Where is the Blood brain barrier?
Between intracerebral blood vessels and brain parenchyma
How is the BBB formed?
It’s formed by tight junctions between epithelial cells and astroglial feet
Where is the BBB not present?
Circumventricular organs
What are microglia?
Macrophages of the brain.
What is the brain stem?
A conduit for ascending and descending impulses. Also house very important reflex centres for heart rate blood pressure and respiration
What are spinal nerves a mix of?
Motor neurones sensory neurones and sympathetic neurones
