L8 - Neurons and Glia Flashcards
describe some features of the structure of neurones
RER / ribosomes / nucleus / mitochondria / golgi dendrites synapses dendritic spines axon hillock axon
name the 3 layers of the peripheral nervous system
endoneurium (innermost)
perineurium
epineurium (outermost)
describe endoneurium
innermost
delicate connective tissue layer that surrounds individual axons and associated schwann cells
describe perineurium
middle layer
connective tissue
surrounds groups of axons creating fascicles
describe epineurium
outermost
robust connective tissue layer surrounds fascicles
contains blood vessels
what is the myelin sheath made of and what is its purpose
schwann cells wrapped around axon
allows saltatory conduction (quicker conduction)
how can neurons be classified by their function
afferent (sensory) - generate A.P towards CNS
efferent (motor) - generate A.P away from CNS
interneurons - connect neurons in CNS
what are the 3 major structural classifications of neurons
- bipolar
- psuedo - unipolar
- multipolar
describe bipolar neurons and give an example
2 processes leave the cell body
(axon and dendrite)
sesory in retina
which direction does is the axon and dendrite?
axon - Away from cell body
dendrite - towards cell body
describe psuedo - unipolar neurons and give example
appears to have 2 processes but has 1 that splits as soon as it leaves cell body
ganglia to spinal cord
describe multipolar and give example
many processes leave cell body (dendrites)
eg motor neurons
define convergence
when several pre synaptic neurons converge on single post synaptic neurone
define divergence
when pre synaptic neurone diverges into many branches of post synaptic neurons
function of glia
provide support for neurons
classes of CNS glia
astrocytes
oligodendrocytes
ependymal cells
microglia
example of PNS glia
schwann cell
describe astrocyte structure
star shaped
what is most abundant glia in brain
astrocytes
structural roles of astrocytes
Fill spaces between neurons
Support of the blood-brain barrier
Forms the glial limitans
homeostatic roles of astrocytes
regulates levels of :
water
k+
neurotransmitters
what do astrocytes and oligodendrocytes inhibit
axon regeneration
describe oligodendrocyte structure
many branches
oligodendrocyte function
myelinating axons in CNS
what myelinates axons in
PNS
CNS
schwann cells
oligodendrocytes
where are ependymal cells found
lining brain ventricles
lining spinal cord central canal
choroid plexus
what do specialised ependymal cells form? and what does this do
choroid plexus
found within brain ventricles and secretes Cerebral Spinal Fluid
what are microglia
specialised macrophages
function of microglia
respond to inflammation/microorganisms/debris/phagocytes/necrotic tissue
in nerve cells where do action potentials initiate
axon hillock
what disease is associated with demyelination of axons
MS
which way do afferent nerves carry impulses
towards CNS
which way do efferent nerves carry impulses
away from CNS
