1030- Neurons and glia Flashcards
(19 cards)
What can increase the rate of conduction across a neuron ?
Myelination
3 layers of the peripheral nervous system
endoneurium, perineurium and epineurium
endoneurium
delicate connective tissue layer surrounding axon and associated schwann cells
perineurium
connective tissue layer surrounding axons forming fascicles.
epineurium
contains blood vessels and forms the nerve itself , connective tissue layer surrounds individual fascicles.
fascicles
bundles of structures
convergence
where multiple presynaptic neurons join onto one post synaptic neuron
divergence
when the axons of one presynaptic neurons diverge into many branches which end on many different post synaptic neurons.
function of neuroglia
to provide support for neurons
Major CNS classes of neuroglia
astrocytes, oligodendrocytes, ependymal cells, microglia
Major PNS classes of neuroglia
schwann cells
What do astrocytes look like and where are they found
star shaped cells and the majority of them are found in the brain
function of astrocytes
fills the spaces in between neurons , support of the blood brain barrier and forms glal limitants
homeostatic function of astrocytes
regulates water, potassium and neurotransmitter levels, and inhibits axon regeneration
oligodendrocytes
branched cells which inhibit axon regeneration and myelinates the glia
Where are ependymal cells found?
found in the brain ventricles, spinal cord and central canal.
What are microglia and what do they respond to:
specialised macrophages and they reponsond to inflammation , phagocytose necrotic tissue, microorganisms and foreign substances which invade the CNS.
How is the myelin sheath formed ?
schwann cells wrap around one part of the axon which they squeezes the cytoplasm out causing multiple layers of the cell membrane to wrap around the axon.
What do schwann cells promote?
Axon regeneration
