CSB332 Lecture 3 Notes

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Cell and Systems Biology
Francis Bambico

CSB332 Lecture 3 Slide 3 - Glial cell types: o Schwann cells  Myelination in the PNS (e.g., sensory neurons, motor neurons) o Oligodendrocytes  Myelination in the CNS (e.g., brain) o Fibrous and protoplasmic astrocytes  Forms the blood-brain barrier • Blood-brain barrier o Ependymal cells  Lining the inner brain surface in the ventricles o Microglia  Resemble macrophages  Activated in response to inflammation o Radial glial cells  Guide the migration of neurons during development  Important for the development of the nervous system  Acts as bridges for developing neurons to migrate from one point to another during embryonic development of the nervous system Slide 4 - Schwan cells in the PNS and oligodendrocytes in the CNS produce myelin that ensheathe axons o Produce the myelin sheaths that wrap around axons that are important for the transmission or conduction of action potentials o There are signals that are important in the initiation of the myelination process Slide 5 - There is a difference between glial cells and neurons in terms of electrical functioning o Glial cells don’t fire action potentials, but similar to neurons, they get depolarized and hyperpolarized  The resting membrane potential can become depolarized or hyperpolarized • This is because glial cells contain high quantities of leaky K+ channels in its plasma membrane  In neurons, there are a lot of voltage-gated K+, Na+, and Cl- channels  In glial cells, there are voltage-gated Na+ channels, but it is more enriched with K+ channels • K+ channels are expressed mainly in the end feet or in the terminal projections of the glial cells • K+ current is going into the cell via leaky K+ channels • Leaky K+ channels allow for the diffusion of K+ based on differences in the concentration of K+ inside and outside of the cell Slide 6 - Glial cell membranes contain transmitter receptors o Depending on what types of receptors are located in glial cells, different types of neurotransmitters will contribute to the depolarization and hyperpolarization of the glial cells o Transmitter receptors have much lower concentrations relative to K+ channels  Binding of GABA to the receptor triggers signaling of Cl- that goes into the glial cell - Glial cell membranes contain excitatory amino acid transporters o Allow for the reuptake of glutamate and GABA o Play an important role in clearing up glutamate in the ECM  Glutamatergic neurons release glutamate  Glial cells have EAATs that are able to take up glutamate  EAATs prevents the build-up of glutamate, which is cytotoxic Slide 7 - Astrocytes are star-like glial cells located in the CNS, particularly the brain o Contributes to the formation of the blood-brain barrier o Blood-brain barrier keeps certain molecules fro
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