Cells of the NS
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Cells of the NS
neurons and neuroglia (supporting cells)
- convey information from the skin and joints
- carry signals to the CNS
- Cell bodies located within dorsal root ganglion (a "ganglion" is a collection of nerve cell bodies located outside the CNS)
- convey impulses away from the CNS to skeletal muscle fiber
- cell bodies located within CNS
- entire neuron and all fibers located within CNS
- integrate sensory input and motor output
Almost all neurons have two types of fibers
chemicals that cross the synapse (gap between axon terminal and dendrite of follower neuron or effector cell)
Supporting Cells (Glial Cells)
- cells that structurally reinforce, protect, insulate and generally assist neurons
- Do not conduct impulses
- outnumber neurons by 10 fold
Myelin sheaths are made of __.
What are nodes of Ravier
gaps between each cell (Schwann cell) that increase the speed of action potentials jumping from node to node
Glial cells of the CNS
- ependynal cells
Function of satellte cells
- similar to astrocytes in function
- whenever you have clump of neuronal cell bodies (ganglia), they need support--> satellite cell
Glial Cells of the PNS
- Schwann cells: form the myelin sheaths around axons in PNS
- Satellite cells: similar to astrocytes in function
What is myelin?
electrical insulation by concentric layers of membrane; increases speed of impulse propagation
- important for control of the ionic enviornment, especially K (keeps K concentration outside low)
- induce BBB (blood brain barrier: tight junctions between brain capillary endothelial cells don't allow stuff from blood to get to the brain
- glial scar (whenever there is damage (since a scar can't form in the brain due to no fibroblast), the damage is isolated and astrocytes form a barrier around the damaged area)
- form myelin in CNS
- axons of the CNS
- are phagocytic; originate outside CNS
- from outside of the brain, related to monocytes
- if damage is detected, they migrate to damaged area and eat it up
- secrete CSF (which is made by the choroid plexus) and lines brain ventricles
- [choroid plexus is inside the ventricle]
How many cells do Schwann cells wrap around?
HOw many cells do oligodendrocytes wrap aroudn?
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