lecture 2 Flashcards
neuron structure & glial cells
neuroglia in PNS
Schwann cell
neuroglia in CNS
- oligodendrocyte
- astrocyte
- ependymal cell
- radial cell
- microglia
how does Schwann cell myelinate axons?
- one Schwann cell wraps one axon, but one axon is wrapped by many Schwann cells.
- myelin wraps about 100 times with almost no cytoplasm.
which syndrome is due to PNS demyelination?
Guillain-Barre syndrom
which system is myelinated axons associated with?
touch system
which system is non-myelinated axons associated with?
pain sensation
what is the function of non-myelinating Schwann cells?
bundle small axons and help maintain peripheral synapses.
what is Remak Bundles?
Schwann cells bundle small diameter c-fibers into Remak Bundles.
Schwann cells keep them from touching each other by squeezing its cytoplasm between axons
what are the common antigens expressed by oligos (and myelinating Schwann cells)?
- Myelin Basic Protein (MBP)
2. Proteolipid Protein (PLP)
what are the myelin associated growth inhibitors that oligos (but not Schwann cells) express?
MAG, Nogo, OMgp
which disease could be a CNS demyelinating disease?
Multiple Sclerosis
how can Astrocyte be identified?
identifiable by expression of glial fibrillary acidic protein(GFAP) and Aldehyde Dehydrogenase(ALDHL1)
what factors do astrocytes release during development?
cholesterol and throbospondins that help promote synapse formation
what does Tripartite synapse mean?
the functional synapse is not just presynaptic axon and postsynaptic dendrite. The associated glial process should be considered to participate as well
the function of astrocyte at synapses?
- neurotransmitter uptake, processing and recycling
- responding to neural activity (astrocytes express some neurotransmitter receptors which can cause intracellular increases in Ca2+ in response to neural activity)
- releasing neuromodulatory factors, including D-serine, ATP, and glutamate)
how is astrocyte used to cure ALS?
ALS is being treated using drugs that enhance glutamate transporter activity in glia.
How do astrocytes interconnect to form networks?
astrocytes interconnect through gap junctions to form networks.
how do astrocytes link neuronal activity to local blood flow?
it is an intermediate for the exchange of nutrients and other molecules between neurons and blood
what is the basis of fMRI BOLD signal?
astrocyte link neuronal activity to local blood flow
what is the function of ependymocytes?
- ependymal cells line the ventricles
- they beat cilia to circulate cerebrospinal fluid (CSF)
- the Choroid Plexus, which is makes CSF, is composed of ependymal cells and blood vessels.
what are the functions of radial cells?
- serve as a scaffold for radially migrating neurons
- radial glia give rise to all classes of macroglia and neurons
- radial glia are developmentally transient except for the Muller Glia in the retina and the Bergmann glia in the cerebellum.
where are microglia derived from?
microglia are foreigners in the brain.
myeloid mileage cells are derived from mesoderm (yolk sac) rather than ectoderm (radial glia)
what are the three primary germ layers in the very early embryo?
- endoderm (most proximal layer)
- mesoderm (middle layer)
- ectoderm (most distal layer)
what are the functions of microglia?
- microglia are dedicated immune cells for the CNS (because of the blood-brain barrier, the CNS is isolated from the immune system, so microglia serve as an immune system for CNS)
- they respond to infection or injury by producing rapid morphological and biochemical changes-they release inflammatory cytokines.
- microglia are small migrating cells that scavenge debris in the CNS
you have discovered a new ion transporter that you guess only exports Na ions. You wish to see if this new transporter either a) harness some other inward ionic concentration gradient to export the Na or b) uses energy from ATP hydrolysis to export Na. which of the following would be futile towards answering this question?
decrease the external concentration of the other likely ion and see if the export of Na decreases as you do so.
use a drug to block ATP synthesis to see if the export of Na decreases.
