Supporting cells to the nervous system Flashcards
What composes the meninges
It is a protective membrane consisting of dura matter, arachnoid membrane, and pia matter
dura matter=
layer of the meninges. It is the outer layers and is thick, tough and flexible.
arachnoid membrane=
middle layer of the meninges- soft and spongy providing cushioning and is impermeable t stop CSF leaks
pia matter=
clings to surface of brain and spinal chord and is thin and delicate. smaller blood vessels are found in the pia matter- also impermeable.
How do meninges differ in PNS to CNS
In PNS dura and pia matter fuse forming a sheath to protect spinal and cranial nerves and autonomic ganglia
as arachnoid membrane is not present as CSF is not present
What is our ventricular system?
ventricles are hollow interconnected spaces within the brain filled with CSF.
We have 4 ventricles= 3rd ,/ lateral/ cerebral aqueduct (connects 3rd and 4th)/ 4th
What is CSF
consists of ions, water, protein, glucose and is produced by choroid plexus of the lateral ventricles flowing to the 3rd then 4th ventricles
what are the functions of CSF
Protection/ buoyancy/ waste reduction/ transport.
GLIA= micro glia
smallest glial cells- known as phagocytes- representative in the immune system in brain- protect brain from invading microorganisms. Primary responsible for inflammatory reaction in response to brain damage. Thought to have a role in neurodegenerative disorders such as Parkinsons and viral infections such as HIV
GLIA- astrocytes
star shaped glia- responsible for physical support/glue for neurons.
They nourish neurons by wrapping blood vessels to store and release nutrients to neurons.
They also limit NT dispersion by surrounding and isolating synapses.
They maintain the blood brain barrier.
astrocytes role in phagocytosis
clean up dead cells in the brain- special astrocytes move around CNS engulfing and digesting debris to then form scar tissue in place of dead tissue.
GLIA= oligodendrocytes and Schwann cells
shwann cells located in PNS
oligodendrocytes located in CNS
They both contain fatty tissue called myelin that warps around neuron axons forming an isolating myelin sheath
CSF LEAK
Occurs when a tear or hole happens in the dura (protective layer of CNS)
other causes- spinal tap, epidural, injury to head or spine, tumour.
to test= CT myelography
a lack of csf causes the brain to sink to the bottom of the skull which is why pain is better lying down.
Other symptoms- clear watery drainage from ear or nose, hearing loss, metallic taste in mouth, head pain, vomiting, meningitis
Meningitis
swelling of the meninges-
test it via a spinal tap
a positive test= cloudy CSF
CAUSE- viruses or bacteria/ ear infection to the brain/ infection into brain due to brain injury/ presence of emboli that have disloged from infection of the heart / unclean hypodermic needlesthose who use intravenous drugs are at high risk.
SYMPTOMS- stiff neck, confusion, loss of consciousness. These neck movements cause the meningitis to stretch and this stretch causes extreme pain.
Hydrocephalus can also be a cause- damage the brain by cutting blood circulation or blocking flow of CSF
