Neurons Flashcards
where do APs propagate from on a neuron
axon hillock
what stain stains myelin
luxor fast blue
what stain stains Nissl (RER)
cresol violet
what colour does eosin stain proteins
red
what colour does haemotoxylin stain nucleic acids
blue
what are the 3 functional classes of neurons
afferent
efferent
interneurons
Where are interneurons
found within CNS
lie entirely within CNS
what do afferent neurons do
convey info from tissues/ organs to CNS; sensory receptors on peripheral ends so respond to physical/ chemical changes in environment by generating signals in the neuron
what do efferent neurons do
convey info away from CNS to effector cells
have cell bodies/ dendrites within CNS
what do interneurons do
connect neurons within CNS
what is the composition of myelin
70& lipid
30% protein
highly compacted
20-200 layers of modified plasma protein wrapped around axon by nearby surrporting cells
where are oligodendrocytes found
CNS
where are Schwann cells found
PNS
what are nodes of Ranvier
where plasma membrane of axon is exposed to extracellular fluid
where are myelinated axons mainly found
somatic nerves i.e. fast sensory/ motor systems
where are unmyelinated axons mainly found
post-ganglionic autonomic fibres, fine sensory fibres, olfactory neurons and interneurons
what is the difference in thickness between myelinated and unmyelinated axons
myelinated are thicker
what are the 5 types of glial cells
oligodendrocytes schwann cells astrocytes microglia ependymal cells
describe oligodendrocytes
glial cells of CNS
myelinating cells that myelinate multiple axons
Provide metabolic support for axons
describe Schwann cells
glial/ myelinating cells of CNS
myelinate single axons
what are the differences between oligodendrocytes and Schwann cells
CNS v PNS
myelinate multiple axons v single axons
what is the name of astrocytes in grey matter
protoplasmic
what is the name of astrocytes in white matter
fibrous
where are protoplasmic astrocytes found
grey matter
where are fibrous astrocytes found
white matter
what are 3 types of astrocytes
radial glia
muller glia
Bergmann glia
what do astrocytes do
regulate ECF composition in CNS
stimulate formation of tight junctions between cells in CNS capillary walls
foot processes closely applied to capillaries
sustain neurons metabolically
how do astrocytes regulate composition of ECF in CNS
remove K+/ neurotransmitters
take up glutamate and convert it to glutamine that can then be taken up by neurons and converted to glutamate
where are radial glia found
guide developing neurons - not found in adult brain
what are muller glia
specialised radial glia in retina
here are Bergmann glia found
cerebellum
describe microglia
specialised macrophage like cells phagocytic immune function in CNS migrate to site of damage contribute to synaptic plasticity
describe ependymal cells
line ventricles
regulate production/ flow of CSF
have cilia, microvilli and desmosomes
barrier between CSF and brain
