Nervous System Components Flashcards
What are the non-neural cells and the excitable cells in the brain?
Glia and neurons
What makes the nervous system special?
~ 6000 genes expressed in brain only
~ 8000 ubiquitois genes
What are gating properties?
conditions that open gated channels (ex. amount of calcium required)
How are glial cells essential elements for neural electrical functions?
1) modulate synaptic function
2) role in brain metabolism
3) maintain chemical homeostasis
4) regulate blood flow through capillary beds
5) provide “immune” type functions
6) provide a scaffold for neuronal migration during development
How do glial cells differ from neurons?
They are non-excitable, have different functions and are replaced by precursors throughout adulthood
What classes of glial cells are there?
1) astrocytes
2) oligodendrocyte or schwann cell
3) microglial cells
4) ependymal cells (includes radial glia)
What is the difference between vertebrate and invertebrate?
Invertebrates have less glial cells that are not as specialized
What/where are ependymal cells?
endothelial cells that line the ventricles
What can ependymal cells produce?
some can produce cerebrospinal fluid
What are ependymal cells derived from?
radial glia which are present during development
What are tanycytes?
a subtype of ependymal cell that lines the third ventricle to the hypothalamus and is involved in transferring signals from CSF to the CNS
How does brain development occur?
cell surface proteins act as signals to attract and motivate neurons to migrate along the surface of radial glial cells
What do schwann and oligodendrocytes do?
myelinate neurons by wrapping around them and increasing electical resistance by insulating
What are the key differences between schwann and oligodendrocytes?
schwann cells wrap around a single motor neuron axon in peripheral nerve whereas oligodendrocytes wrap around multiple neurons each in CNS
What functions do microglia serve?
1) main elements of intrinsic immune system
2) sense brain injury and clear cellular debris
3) implicated in brain inflammatory responses, cognitive deficits, percussive brain injury, stroke damage
How do microglia work?
check the environment by redistributing membrane (filpodia) and engulf and digest damaged tissue (phagocytotic)
What are microglial derived from?
hemopoetic stem cells in bone marrow
What are some of the functions of an astrocyte?
1) influencing integrity of BBB
2) removal of glutamate and GABA at synapses
3) synthesis of precursor for glutamate and GABA production
4) and more…
How do astrocytes maintain the BBB?
form tight junctions with foot processes so that proteins, drugs and charged molecules cannot diffuse
How is synaptic activity coupled to glucose usage?
astrocytes do this by coupling glutamate upatke with glucose utilization
How do astrocytes help to regulate blood flow to active brain regions?
they control the arteriole diameter (as calcium concentration increases they signal arterioles to contract and vice versa)