Lectures 5-8: Neuroanatomy Flashcards
astrocytes =
type of glia…
cellular extensions interact with synapses and blood vessels
control composition of extracellular space to allow neuronal function
form scar tissue after injury
microglia =
type of glia…
brain macrophages
clear infections and debris
oligodendrocytes =
cellular extensions form insulating myelin sheath around axons to allow rapid nerve impulse conduction
most abundant type of cell body in the corpus callosum…
corpus callosum = white matter therefore is composed of myelinated axons = no neurons…
oligodendrocytes
local current is influenced by…
difference between active and resting potential
myelin sheath -
increases membrane resistance and decreases capacitance
node of ranvier -
where ion channels are located
membrane resistance low compared to inter-node
action potential moves by salutatory conduction from node to node, is propagated between nodes by electronic conduction
evidence that current flow occurs at nodes of ranvier…
- current stimuli needed to reach potential threshold is less if locally applied rather than inter-nodes
- local application of anaesthetic to block conduction is more effective at nodes than inter-nodes
voltage clamp =
measures current flowing through ion channels
a feedback amplifier supplies current to rapidly return membrane potential to a chosen level
myelination in CNS -
by oligodendrocytes
myelinate several inter-nodes
myelination in PNS -
schwann cells
myelinate a single inter-node
myelination creates..
distinction between white and grey matter in the brain
ganglion =
collection of neurons in PNS
nucleus =
collection of neurons in CNS
nerve =
a bundle of axons in PNS
tract =
collection of CNS axons with a common site of origin and destination
motor neurons concentrated …
ventrally (belly/front)
- motor fibres activate muscle for movement
sensory fibres concentrated …
dorsally (back) and in head
- input info from environment
fore-brain =
cerebral cortex
basal ganglia
thalamus
hypothalamus
hind-brain =
cerebellum
pons
medulla oblongata
brain stem =
midbrain
pons
medulla
spinal cord…
covered by meninges - pia, arachnoid, dura
and irrigated by cerebrospinal fluid - produced by filtration of blood, circulates through spinal canal and the subarachnoid space
the brain …
protected by skull and meninges and irrigated by cerebrospinal fluid
rostral =
noseward (anterior)
caudal =
tailwards (posterior)
ventral =
belly/front/underneath
dorsal =
back/on top
dermatone =
a region of skin innervated by dorsal roots from one spinal segment
white matter =
ascending and descending myelinated and unmyelinated axons
grey matter =
contains neuronal cell bodies
hypothalamus =
head ganglion of the autonomic nervous system
secretes vasopressin and oxytocin via posterior pituitary gland
releases hormones to induce secretion of hormones from anterior pituitary gland
motor unit
an alpha motor neuron and the group of muscle fibres it innervates
two types of neural lesion/ dysfunction :
1) white matter = interrupted axnol conduction
2) grey matter = death of neurons
syndromes affecting white or grey matter -
spine/head injury
stroke
infection e.g meningitis
neural tumour
diseases primarily affecting white matter:
multiple sclerosis ( CNS inflammatory demylination)
paraplegia (distal degeneration of spinal cord)
neuropathy ( distal demyelination of peripheral nerve)
diseases primarily affecting grey matter
motor neuron disease (spinomuscular atrophy)
cerebellar diseases
basal ganglia diseases (Huntington’s, Parkinson’s)
temporal/frontal lobe diseases (Alzheimer’s, dementia)
