Neural Tissues Flashcards
What is the purpose of the nervous system?
communication sensory detection information processing motor activity behaviour
What is the CNS responsible for?
information processing
reflexes
behaviour
What is the PNS responsible for?
sensory detection
motor activation
What is the difference between an afferent and an efferent neuron?
afferent neuron: transmits sensory information to the brain/spinal cord
efferent neuron: motor neurons transmitting information from the brain to the effector organ
What is a ganglion?
a group of cells outside the CNS
motor: eccentric (peripheral) nuclei, small neurons
sensory: central nuclei, big neurons
What are Brodmann areas?
regions of the cortex numbered 1-52
boundaries determined by cell architecture
each has particular set of inputs/outputs
often functionally distinct
What is Brodmann Area 17?
primary visual cortex
What is Brodmann Area 4?
primary motor cortex
What is a ‘process’?
generic term for any outgrowth from the cell bdy
A CNS neuron: …
has a nucleus within the cell body
extends one or more processes
What is myelin?
electrical insulator
wrapped around axon
made up of many layers of cell membrane
increases conduction velocity
Neuron classifications
multipolar
bipolar
unipolar
Features of a chemical synapse
big gap (~30nm)
common throughout nervous system
signalling not in retrograde direction
presynaptic cell releases neurotransmitter
postsynaptic cell produces electrical signal
What is the difference between divergent and convergent signals?
divergence = single neuron sends output signal to many neurons convergence = multiple inputs influence single neuron
What are interneurons?
only present in CNS neither motor nor sensory - relay process signals can be excittory or inhibitory = 80% of the brain
What are glia?
supply and protect neurons oligodendrocytes astrocytes microglia ependymal cells Schwann cells satellite cells
What are oligodendrocytes?
glia in CNS
produce/maintain myelin sheath
one cell can myelinate multiple axons
What are astrocytes?
glia in CNS
support neurons - assists in development/growth
protect neurons from harmful substances
star-shaped
‘feet’ on processes on blood vessel endothelium
influence blood flow and blood-brain barrier
controls local vasodilation
What are microglia?
glia in CNS immune cells - protect neurons from disease migrate to injury sites engulf microbes/debris mesodermal origin
What are ependymal cells?
glia in CNS
lines brains ventricles and central canal of spinal cord
forms CSF
cilia and microvilli on apical membrane
What are Schwann cells?
glia in PNS
produce/maintain myelin sheath
PNS regeneration
1 axon wrapped per Schwann cell
What are satellite cells?
glia in PNS
support neurons
regulate exchange of materials between neurons and interstitial fluid
perform similar role to astrocytes
Give an example of a glial pathology.
glioma largest group of primary tumours derived from glial cells usually highly malignant grows rapidly difficult to surgically remove usually inside cranium
Give an example of a neural pathology.
neuroblastoma
tumour (cancer)
most common in children and infants
derived from neural crest cells from sympathetic nervous system
often increases catelcholamine levels
survival rates vary
survivors often develop neurological problems ~30 years later
