Nervous system Flashcards
CNS
central nervous system
brain and spinal cord
neurons and glia
PNS
peripheral nervous system
peripheral nerves that go out into the body
neurons and glia
Glia
chemical support for Neurons
4 in the CNS
1 in the PNS
each type has its own function
Neurons
cells specialised for transmission of information
many different types of information and there are thousands of different types
Astrocytes
CNS supply nutrients to the cell ensheath blood capillaries transmit information star shape
Microglia
immune cells for the CNS
engulf microorganisms and debris
oval with lines shape
surveys brain health and engulfs pathogens
Ependymal cells
CNS
lining of the brain
line fluid filled spaces of brain and spinal cord
have cilia (hair like) processes to circulate the cerebral spinal fluid (CSF)
squares beside each other
Oligodendrocytes
CNS
supports nerve fibres
ensheath nerve fibres with myelin
spider shape
Schwann cell
PNS
supports the peripheral nerve fibres with myelin
similar to oligodendrocytes
like glad warp wrapped around he axon of the neuron
it has its own nucleus at the end of the wrapping
Myelin sheath + Nodes of Ranvier
a lipid (fat) wrapped around the axon
in the CNS it comes from oligodendrocytes
in the PNS it comes from the Schwann cell
increases the conduction velocity
multiple Schwann cells in a line
NOR are the gaps between each of the Schwann cells that increase conduction.
Structure of a Neuron
dendrites cell body axon axon terminal myelin sheath and nodes of Ranvier (sometimes)
Dendrites
receives input signal
sends info to the cell body
squiggly bits at the top of a Neuron
Cell body
contains the nucleus and the organelles
sums up the input signal and organises it.
triangle bit of the Neuron
Axon
carries electrical impulses
may or may not be myelinated
long stick part of the neuron
Axon Terminal
the end of the neuron/ axon
where the neurotransmitter is released
2 little sticks at the end of the long axon
importance of Myelination
demyelination of nerve cells could be caused by autoimmunity or infection (immune system attacks myelin)
causes impaired nerve conduction
weakness, incoordination, visual and speech impairment
Input zone of neuron
dendrites + cell body
receives the chemical signal from the neurons
Summation zone of neuron
axon hillock ( bottom part of the cell body)
where the decision of weather to transmit the signal is decided
info is gathered and a decision is made
Conduction zone of neuron
Axon, may be very long
carrying electrical signals between brain areas, to and from the spinal cord or to and from periphery sensor receptors
Output zone of neuron
Axon terminals
contact with input zone and other neurons
release of the neurotransmitter (chemical signal)
Multipolar Neuron
multiple dendrites
single axon
multiple processes from the cell body
Bipolar axon
2 processes come from the cell body
one functions as a dendrite and one functions as the axon
Unipolar axon (pseudo)
one process comes from the cell body then branches into the dendrite and the axon
Synapse
the neurotransmitter release
includes the synaptic cleft, pre and post synaptic neurons
most common in the CNS is the Axodendritic synaptic
Pre synaptic neuron
before synapse
contains synaptic vesicles (little pockets of neurotransmitter)
neurotransmitter is released from the axon terminal
Post synaptic neuron
after synapse
contains the receptors for the neurotransmitters
Afferent/ ascending
flow of information into the brain
Efferent/ descending
Flow of information out of the brain
