wk 1 neorology Flashcards
regional neuroanatomy
The name and location of structures at macro- and microscopic resolution
cellular neuroanatomy
The types and microstructure of the cells that make up the nervous system
functional neuroanatomy
The pathways that deliver coherent functions of the nervous system
dorsal column pathway
Proprioception
Vibration
Fine touch
spinothalamic pathway
Pain
Temperature
types of glia
Astrocytes, oligodendrocytes / Schwann cells, microglia
key concepts of neurones
chemical synapse for cell-signalling
slow (diffusion) can induce ‘GAIN’
‘drugable’
gain
measured as the slope of the current-frequency (input-output) relationship over any given range of inputs
sensory receptors can be…
‘Free’ nerve endings (NEs)
Specialised NEs
Specialised nerve cells
schwann cells
insulation - myelin sheath
1:1 ratio with axon
PNS
oligodendrocytes
insulation - myelin sheath
1:n ratio with axon
CNS
astrocytes
Central to BBB integrity - vascular foot process that wraps round capillaries
maintain chemical concentrations
remove waste
repair
microglia
Resident macrophage of the CNS
Complex roles in development, immune surveillance, disease response & tissue repair
action potential summary
Stimulus depolarises the membrane
Triggers opening of voltage-gated Na channels – depolarisation
Then voltage-gated Na channels close and K channels open – repolarisation
This leads to brief ‘hyper-polarisation’
A further AP cannot be induced until the end of the refractory period
triggers of AP
1) Localised ion channel state-change (open/closed)
Ligand gated ion channels (open when appropriate ligand bind)
Voltage gated ion channels (open in response to voltage change)
2) Propagation of charge from adjacent region
saltatory conduction/propagation
Increases conduction velocity
Lowers energy expenditure (Na/K-ATPase)
along myelinated axons from one node of Ranvier to the next node
Glutamate
AMPA – fast acting
NMDA – have Mg2+ block
Metabotropic – G-protein coupled
ex
Acetylcholine
Nicotinic – fast acting
Muscarinic – slower acting
Noradrenaline
Flight or fight
α and β receptors
ex
serotonin
Multiple roles
ex
dopamine
Basal ganglia functions & reward
ex
GABA
Linked to a Cl- channel
Cl- hyperpolarises the cell making it more difficult for the cell to fire
Alcohol is a GABA-like molecule
Act through benzodiazepine receptors – utilised in clinical medicine with benzodiazepines e.g. Diazepam
inh
chemical transmission
ACh release into synaptic cleft
Rapidly degraded by Acetylcholinesterase
AChR binding at motor end plate opens ion-channel
Na+ influx / K+ efflux causes depolarisation of muscle
Depolarisation triggers propagation of AP in muscle fibre
anatomy of muscle
Repeating unit is the sarcomere
Sarcomere comprises: Z-disc, thick (actin) and thin (myosin) filaments
Actin is blocked from interacting with myosin by tropomyosin, in turn controlled by troponin.
muscle contraction
Ca+ influx binds to troponin and unblocks the action of tropomysosin exposing actin activity sites
Myosin heads alternatively attach and detach, pulling the actin filaments towards the centre of the sarcomere
Ca+ actively removed by uptake into the SR
Tropomyosin block restored
bilaminar disc
epiblast and the hypoblast, evolved from the embryoblast.
These two layers are sandwiched between two balloons: the primitive yolk sac and the amniotic cavity.
trilaminar disc
created through migration of epiblast cells through the primitive streak
what layer is the NS derived from
ectoderm layer