lecture 22 Flashcards
what are 6 functions of neuroglial cells?
- provide the framwork for the neural tissue
- maintain the intercellular environment
- act as phagocytes
- over 100 billion (more astrocytes than any other)
- roughly five times the number of neurons
- have the ability to reproduce
what are the neuroglia in the CNS?
astrocytes
oligodendrocytes
microglia
ependymal cells
what are the neuroglia found in PSN?
satellite cells
schwann cells
what do oligodendrocytes do?
myelinate CNS axons provide structural framework
what do astrocytes do?
maintain BBB
provide structural support
regulate ion, nutrient and dissolved gas concentrations
absorb and recycle NT, form scar tissues after injury
what do microglia do?
remove cell debris, wastes, and pathogens by phagocytosis
what do ependymal cells do?
line ventricles and cental canal assist in producing, circulating and monitoring cerebrospinal fluid
what do satellite cells do?
regulate the exchange of material between the cell body and the environment
what do schwann cels (neruolemmocytes) do?
form a myelin sheath
what do satellite cells and peripheral neurons surround?
surround neurons soma: regulate local environment
schwann cells and peripheral neurons:
envelop what ?
envelop axons to form protective cover (neurilemma)
multiple layers of schwann cell membrane creates the myelin sheath
muscle innervation:
skeletal muscles are innervated by what?
motor neurons
what is a motor unit?
motor neurons + the muscle fibers it innervates
what does the cerebrum consist of?
inner and outer regions of grey matter
cortex
gray = soma and unmyelinated fibers
tracts of white matter = myelinated fibers
brain cancer:
most brain cancer are derived from what?
neuroglial cells not neurons
how do tumours develop?
by cell division
1) neurons dont replicate or divide
2) neuroglial cells normally divide at low rate
what is Glioblastoma multiforme ?
grade 4 malignant tumor
the meninges of the brain:
what are the parts of the Dura mater?
endosteal layer
meningeal layer
the meninges of the brain:
parts of the Arachnoid
arachnoid granulations
subarachnoid space
what are the three layers of the meninges?
dura mater
arachnoid
pia mater
what is the arachnoid mater?
web-like collagenous fibers underlining the arachnoid layer
Subarachnoid space
help anchor cerebral blood vessels
CSF here
Arachnoid granulations are what?
CSF flows through these and into blood circulation
what is the Pia mater?
attached to the surface of the brain
follows sulci and gyri of brain
helps anchor larger blood vessels of the cerebrum
Ventricles of the brain:
how many ventricles?
what do they do?
4 CSF fluid filled cavities
transports nutrients and waste to/from CNS
provides physical protection
2 lateral ventricles
third ventricle
forth ventricle
What do the lateral ventricles do?
interventricular foramen conects to third ventricle
what do the third ventricle do?
aqueduct of midbrain connects to foouth ventricle
What do the fourth ventricle do?
adjacent to pons, connects to central canal, median and lateral apertures
what is the choroid plexus lined with?
ependymal cells
What do ependymal cells do?
form selective barrier
involved in active transport
(nutrients, vitamins, ions into CSF)
Path CSF takes around brain
CSF moves from subarachnoid space into dural sinus via arachnoid granulations
sinuses drain into internal jugular vein
what are the functions of CSF?
protection- cushioning preventing contact of neural structures and bone
supporting the brain : brain suspended in CSF
transporting nutrients, chemical messengers, and waste products
cerbral spinal fluid is produced by cells in what?
choroid plexus
