ANATOMY - nervous system Flashcards
what does the CNS consist of
spinal cord and brain
which part of a neurone passes on action potentials (APs)
axons
which part of a neurone receives action potentials (APs) from another neurons axon
dendrite
what is ‘the powerhouse’ of the neurone
body/soma
what is in the body/soma of the neurone that classifies it as the ‘powerhouse’ of the neurone
mitochondria
ribosomes
nucleus/ganglion
ER
etc
which part of the neurone is in between the body/soma and the axon
axon hillock
what is the significance of the axon hillock
generates most action potentials (APs)
what is the difference between a nucleus and a ganglion
ganglion is found in PNS
nucleus is found in CNS
both parts of the neuron body/soma
how does neuronal injury occur
ischaemia/hypoxia
which part of the brain has most neurones
cerebellum
what is a nerve
what is a tract
(clue: theyre similar)
nerve - collection of axons in PNS
tract - collection of axons in CNS
where is the myelin sheath
what is its purpose
wraps around axons
insulator/conductor = faster AP transmission speed
what is the function of a schwann cell/oligodendrocyte
produce myelin
where are oligodendrocytes and schwann cells found (CNS/PNS)
oligodendrocytes - in CNS
schwann cells - in PNS
what is the difference in function between a multipolar and unipolar neurone
multipolar - motor signals (from CNS to PNS - so body in CNS)
think multipolar because motor signals need to go to more than one place (lots of diff parts of one muscle)
unipolar- sensory signals (from PNS to CNS - so body in PNS)
think unipolar bc sensory signals come from one specific place and go to one specific location
where is the body/soma of a unipolar neurone
PNS (bc that’s where it originates)
where is the body/soma of a multipolar neurone
CNS (bc that’s where it originates)
what is another name for a multipolar neurone
lower motor neurone (LMN)
what are the 4 types of glial cells
astrocytes
oligodendrocytes
microglia
ependymal cells
what is the purpose of astrocytes
maintain blood brain barrier
what does damage to astrocytes look like on histopathology
gliosis - increase in number and size, old lesions become dark
what do astrocytes normally look like on histopathology
star shaped
what is the most important histopathological marker of CNS damage
astrocyte gliosis
what do oligodendrocytes do
produce myelin for axons in the CNS
what is the purpose of the myelin sheath
insulator around the axons = increases conduction velocity of APs
how many myelin sheaths does an oligodendrocyte produce
lots! - in between several axons
in what conditions are myelin sheaths and oligodendrocytes important
give 2 examples
demyelinating disorders
eg multiple sclerosis, guillane barre
what is damaged in demyelinating disorders
what does this result in
oligodendrocytes (in CNS not schwann cells in PNS)
decreased myelin sheaths
= slowed conduction of signals from brain to body and vice versa
what is the node of ranvier
in areas where the axon is exposed as there is no myelin sheath coverage (unmyelinated part of axon)
what is the significance of the node of ranvier
precipitates rapid saltatory conduction
what types of cell are microglia
immune cells
when do you see microglia
when damage has happened (there to fix the problem - immune cells)
what are ependymal cells
cells (epithelium) lining the ventricles
when do ependymal cells get damaged
by viruses
is there connective tissue in CNS
no apart from around blood vessels
how fast is the damage if necrosis has occurred
fast
eg stroke
how fast is the damage if atrophy has occurred
slow
eg age related cerebral atrophy
where do sympathetic nerves leave the spinal cord
T1-L2 (thoracolumbar region)
what happens to sympathetic nerves once they leave the spinal cord (to heart and lungs)
synapse in ganglia next to the spinal cord (PARAvertebral ganglia)
then travel through cardiopulmonary splanchnic nerves to heart and lungs
what happens to sympathetic nerves once they leave the spinal cord (to abdominopelvic organs)
synapse away from the spinal cord (PREvertebral ganglia)
then travel to applicable organs via specific nerves
which 4 cranial nerves do ALL parasympathetic outflow leave the brain via
CN III, VII, IX, and X (mainly vagus but others too)
plus sacral spinal nerves (to pelvis, perineum and hindgut)
