IB 131 LEC 13

what do multipolar neurons posses?

dendrites and a single axon

what represents the most common structural type in the CNS?

multipolar neurons

what do bipolar neurons feature?

two distinct extensions from the soma

what does the first fused dendrite do in bipolar neurons?

receives highly targeted sensory input

what does the second fused dendrite do in bipolar neurons?

transmits the signal

where can bipolar neurons be found?

bipolar layer of eye

olfactory epithelium

how are pseudounipolar neurons characterized?

single short process from soma into PNS and CNS

what are neuroglia (glial cells)?

non-neuronal support cells

what is the purpose of glia?

regulators of homeostasis

synaptic communication

blood flow

where are glial cells located?

CNS and PNS

where are astrocytes located?

CNS

what is the most abundant CNS glia?

astrocytes

what is an essential component of the tripartite synapse?

astrocytes

what do astrocytes do?

regulate blood brain barrier

maintain ion and neurotransmitter balance

where are oligodendrocytes located?

CNS

what do oligodendrocytes do?

produce myelin sheaths in CNS

where are microglia located?

CNS

what do microglia do?

immune cells of CNS

where are ependymal cells located?

CNS

what do ependymal cells do?

line the ventricles and central canal

where are schwann cells located?

PNS

how do schwann cells work?

form myelin sheaths around PNS axons

where are satellite cells located?

PNS

what do satellite cells do?

surround neuronal somas

what is myelin made of, what does it do?

lipids

increases velocity of electrical signals

what does myelin prevent?

transmembrane ion current leakage

what are high concentrations of voltage-gated sodium channels restricted to?

uninsulated gaps (nodes of ranvier)

what is saltatory conduction?

electrical nerve impulse (action potential) jumps myelinated axon

what happens when there is axonal damage?

voltage gated channels disperse along axon length

what is grey matter made of?

neuronal cell bodies

dendrites

unmyelinated axons

synapses

what is grey matter responsible for?

neural processing and integration

what is white matter made of?

myelinated axon tracts

what does white matter do?

mediates long distance communication

in the cerebellum, what receives sensory/motor inputs?

outer cortical grey matter

in the cerebellum, where do output pathways originate from?

deep gray nuclei

what is the brainstem a mixture of?

gray and white matter

what pattern is the spinal cord organized in?

inverse pattern

how does the CNS originate?

hollow neural tube

what does the anterior neural tube expand into (vesicles)?

forebrain

midbrain

hindbrain

what is the primary vesicles of the forebrain?

prosencephalon

what are the secondary vesicles of the forebrain?

telencephalon

diencephalon

what are the associated ventricle with the prosencephalon?

lateral ventricles

third ventricle

what is the primary vesicle of the midbrain?

mesencephalon

what is the secondary vesicle of the midbrain?

mesencephalon

what is the associated ventricle of the midbrain?

cerebral aqueduct

what is the primary vesicle of the hindbrain?

rhombencephalon

what are the secondary vesicles of the hindbrain?

metencephalon

myelencephalon

what is the associated ventricle with the hindbrain?

fourth ventricle and central canal

what is cerebrospinal fluid?

clear acellular fluid

what is cerebrospinal fluid produced by?

choroid plexi

what does choroid plexi do?

filter blood plasma

what does choroid plexi filter in?

glucose

oxygen

essential ions

what are the lateral ventricles?

paired horseshoe cavities within cerebral hemispheres

what is the interventricular foramen?

channel connecting lateral ventricle to midline third ventricle

what is the cerebral aqueduct?

narrow conduit traversing midbrain

what is the fourth ventricle?

pyramid shaped cavity

where is the fourth ventricle located anteriorly and posteriorly?

cerebellum

pons and upper medulla

where are the exit portals for cerebrospinal fluid?

median and lateral aperture

what does the CSF (cerebrospinal fluid) provide?

buoyancy

how is CSF reabsorbed?

arachnoid granulations into venous dural sinuses

where does dural venous blood and reabsorbed CSF exit, via what?

cranium via internal jugular vein

the obstruction of csf flow or impaired reabsorption leads to?

hypocephalus (water on brain)