QUIZ 7- Intro Flashcards
Operational Design Conditions
CNS must have hierarchal organization (top down)
CNS must have structural and functional stratification (neurons controlling same process must be in the same space)
CNS must demonstrate plasticity (must change because human body is not static)
CNS
brain and spinal chord physically separate from PNS by Blood brain barrier (BBB)
afferent
inward axonal projections
efferent
outward axonal projections
CNS composition
10% neurons (50% of volume)
90% neuroglia (50% of volume)
nuclei/ganglia
collection of neuronal cell bodies with the same function in the same physical space
tunneling nanotubes
membrane projections connecting neurons
gray matter
neuronal cell bodies
white matter
axonal projections
ganglia
collection of neurons with the same function in the same physical space outside the CNS
circuits
anatomical and functional connections between neurons
multipolar neurons
common CNS neuron with single axon, short dendrites
pyramidal neurons
common, largest CNS neurons, multiple long axons
neuroglia
non-neuronal cells within CNS
Critical Concepts
diffusion moves small particles
structure dictates function
to function CNS needs chemical isolation from rest of body
CNS needs separation from blood
3 Meninges
Dura mater
Arachnoid Mater
Pia Mater
Dura Mater
“tough mother”
two fibrous layers
space between layers filled with blood/lymphatic vessels and ECF
subdural space
dural venous sinus
subdural space
between the dura and arachnoid space
dural venous sinus
drainage system allowing CSF to re-enter blood
Subdural Hematoma
physical trauma leads to bleeds onto brain surface
increased fluid pressure leads to neuronal cell damage
Arachnoid Mater
“spider-like mother”
epithelial cell layer that doesnt follow the brains underlying sulci or gyri
subarachnoid space
arachnoid villi
sulci
furrow
gyri
smaller ridge/cleft
subarachnoid space
between dura and pia mater
arachnoid villi
move through venous sinuses allowing CSF to exit subarachnoid space
Pia Mater
“gentle mother”
directly on surface of brain
accompanies branches of cerebral blood vessels
coverage and protection of CNS tissue, blood vessels containing CSF
meningitis
viral/bacterial infection leading to inflammation of pia mater
causes severe headaches
highly infectious
vascularization
constant 15-20% of cardiac output
internal carotid and vertebral arteries
internal jugular vein
anastomose
fusion of blood vessels
circle of Willis
alternative paths for blood flow
ensures blood supply
Brain Interstitial system
fluid-filled space between neurons and capillaries
immediate environment surrounding neurons
originates from cerebral spinal fluid and blood vessels
BBB composition
capillary endothelial cells
basal lamina
astrocytic endfeet (control point)
pericytes (angiogenesis)
BBB features
highly selective permeability
limited paracellular path
control of Interstitial space
Neurovascular unit composition
capillary endothelial cells
pericytes
astrocytes, microglia
neurons
Neurovascular unit function
regulation of blood flow and BBB
Blood Brain Barrier
limited transport capacity
carrier-mediated=selective and saturable
receptor-mediated=binding and internalization
hydrophobic compounds are diffusion limited
water-soluble compounds do not diffuse through
CSF access
hydrophobic diffusion- very fast
consequences:
hydrophilic drugs have limited access- bacterial infections are rare
ISF VS Plasma
slightly lower pH from elevated CO2
lower protein content
lower buffering capacity
lower glucose content
lower K+ H30+
CSF location
around and within CNS
CSF function
source of solutes and water for ISF
buoyancy of brain
protection against trauma
ISF functional stability
removal waste product
CSF production
via ependymal cells lining ventricles- fluid-filled spaces
Ependymal cells
line ventricles to form choroid plexus with capillaries
selection and movement of CSF
CSF circulatory path
flows through brain and spinal chord and exits back into blood supply
CSF composition
more like ISF than plasma
CSF and ISF have similar ion concentrations
Neuroglia Roles
surround
support
insulation
housekeeping
development
synaptic transmission
surround
keep neurons in proper place
support
nutrients and O2
insulation
prevent axons from touching
housekeeping
remove pathogens and dead cells
development
axonal migration during fetal development
synaptic transmission
NT removal, neuromodulators
Neuroglia is made up of
oligodendrocytes
astrocytes
microglia
radial glia
oligodendrocytes
CNS myelin production
regulate axonal growth
cerebral palsy
loss of CNS oligodendrocytes
Astrocytes
most abundant, with multiple types
provide surface coverage; limiting solute movement into ISF
part of BBB
regulation of CSF content
microglia
specialized microphages
removal of debris, damages cells, foreign substances
Radial glia
scaffolding in which new neurons migrate
meninges
multiple connective tissue layer that covers the CNS
