Lecture 5 Neural Tissues Flashcards
what is the purpose of the nervous system
communication leading to sensory detection. Via information processing to motor activity to behaviour
what is the CNS
brain and spinal cord
for information processing, including reflexes and behaviour
what is the PNS
Peripheral or parasympathetic
sensory detection and motor activation
why is the nervous system complex
many cells
10^11 neurons, 10^14 synapses, 1.5 kilograms in brain
10^8 neurons in enteric NS (More than spinal cord)
what is an afferent neuron
transmit sensory info to brain/spinal cord
ARRIVES
What is an efferent neuron
motor neurons transmitting info from brain to effector organ eg muscle
EXITS
what is a ganglion
group of cells outside the CNS
eg motor ganglion (autonomic)
basal root ganglia is an exception
what is a parasympathetic ganglion like
smaller neurons and eccentric nuclei
what is a sympathetic ganglion like
eg dorsal root ganglia
big neurons and central nuclei
how is the human prefrontal cortex navigated
Dorsal – lateral axis bends
Rostral – caudal axis bends
curves through head, front R, back C, top D, bottom V
what are the Brodmann areas of the neocortex
regions of cortex numbered 1-52
Each area has a particular set of inputs and outputs.
Often an area will have a function
what does Brodmann area 4 do?
primary motor cortex
what does brodmann area 17 do?
primary visual cortex
what is a CNS neuron like
nucleus within cell body and extends one or more processes
what are the parts of a CNS neuron
dendrites
cell body
axon hillock to axon with axon collaterals, nodes of ranvier, myelin sheath
axon terminals
what is the myelin sheath
many layers of cell membrane wrapped around an axon
what does myelin do
electrically insulates to increase diameter and conduction velocity
breaks - nodes of ranvier
what are the classifications of neurons
multipolar - several dendrites, majority
bipolar - one dendrite and axon either side of cell body
unipolar - or pseudo, one axon and dendrite in single branching process as 2 processes move together
all axons have just one neuron
what are other important neurons
pyramidal cells (axon either side of cell body with dendrite - neocortex - thinking) purkinje cell (small and many, lots of interactions - cerebellum) Dorsal Root Ganglion (psuedounipolar, sensory neuron)
what is a synapse
a functional link
what are post synaptic cells
neuron, myocyte or glands
what is a chemical synapse like
big gap -30nm
common in NS
signalling not in retrograde direction
how to pre and postsynaptic cells interact
presynaptic cell releases neurotransmitter
post synaptic cell is the receptor, turns it to electric signal
what is a divergent neuron
a single neuron sending its output signal to many neurons eg skin
what is a convergent neuron
multiple inputs influence a single neuron eg retina
what are interneurons
occur only in CNS
can be excitatory or inhibitory
they process signals
connect sensory to motor neurons in DRG
what do glia do and not do
no action potentials and do not form synapses
can divide and form myelin sheaths
how do neurons and glia compare
neurons are basic nerve cells, impulse conducting and glia are supportive and protective
1 neuron to every 10-50 glia
what are the glial cell types
ependymal cell astrocyte pia matter microglial cell oligodendrocyte
what do oligodendrocytes do
produce/maintain myelin sheath in CNS
one myelinates multiple axons from different neurons
what do astrocytes look like
star shaped
its ‘feet’ on processes about bv endothelium
what do astrocytes do in CNS
influence blood flow and blood-brain barrier
assist neuronal development/growth (neurotrophic)
protect neurons from harmful substances
what do microglia cells do in CNS
Immune cells to protect neurons from disease, migrate to injury sides, engulf microbes/debris, mesodermal growth
where do microglia come from
mesoderm like other immune cells
what do ependymal cells do in CNS
line brain ventricles and central canal of spinal cord
form CSF
cilia and microvilli on apical membrane
what do Schwann cells do in the PNS
production and maintenance of myelin sheath in PNS
1 axon per Schwann cell (axons have many Schwann cells)
analogous to oligodendrocytes
what do satellite cells in the PNS do
support neurons, regulate exchange of materials between neurones and interstitial fluid
analogous role to astrocytes
what glia are in the CNS
astrocyte
oligodendrocyte
ependymal cell
microglial cell
what cells are in the PNS
Schwann cells
satelite cells
what are the 3 layers of the meninges
3 meningeal layers – Dura matter, Arachnoid, Pia matter (inner most)
what is a glioma
glia pathology largest group of primary tumours from glial cells usually highly malignant grow rapidly difficult to completely remove usually inside cranium
what is a neuroblastoma
neural pathology cancer most common in kids and infants outside cranium from neural crest cells in sympathetic NS survival rates vary but initial prognosis typically good treatment varies on type many develop neural issues in 30's
what is a sign of neuroblastoma
increase in catecholamine levels
